SHARON Nitrogen Removal over Nitrite

SHARON Nitrogen Removal over Nitrite

Index Preamble 5 1 Introduction 7 2 SHARON Nitrogen Removal over Nitrite 9 3 Full-scale experience with the SHARON process through the eyes of the operators 13 4 Reference list 23 SHARON Linköping (SE) 27 SHARON Seine Grésillons (F) 29 SHARON Geneva (CH) 31 SHARON Whitlingham STC (UK) 33 SHARON MVPC Shell Green (UK) 35 SHARON New York (USA) 37 SHARON Garmerwolde (NL) 39 SHARON The Hague (NL) 41 SHARON Beverwijk (NL) 43 SHARON Zwolle (NL) 45 SHARON Rotterdam (NL) 47 SHARON Utrecht (NL) 49 Contact 51 SHARON 5

Preamble For over a decade now, SHARON has proven to be a unique technological process to remove ammonia in wastewater. First in the Netherlands and now also successfully applied at several wastewater treatment plants abroad. After the first assignment outside the Netherlands, for the city of New York in the United States, the SHARON process was subsequently selected for application by authorities in Paris, Geneva, Manchester and Sweden. The SHARON technology received the IWA Regional Project Innovation Award 2008. The technology is a joint development of Grontmij and Delft University of Technology. This co-operation affirms the strategy of Grontmij to ensure continuation of new developments along with universities and research institutions and simultaneously to ensure to market these innovations in a fast and effective manner. Together with our clients, we apply this sustainable technology, tailor-made. The SHARON technology treats wastewater in a stable and reliable way and the process saves cost, space, energy and thus the environment. In this brochure you will find a list of our SHARON projects alongside our clients experiences with the SHARON technology. Hubert Habib Director Infrastructure & Environment SHARON 7

1 Introduction Stable High rate Ammonia Removal Over Nitrite. SHARON is a cost-effective treatment system for the total removal of nitrogen from wastewater. The system is used for treatment of high strength ammonia liquors. A typical application is the treatment of liquors from dewatered digested primary sludge and waste activated biosolids at municipal wastewater treatment plants. It may also be used to treat wastewater flows from sludge dryers and incinerators. SHARON is a biological nitrification/denitrification process operating with minimal sludge retention time. Due to differences in growth rates of the bacterial species at the process design temperature (30-40 C) a selection can be made wherein the nitrite oxidizing bacteria are washed out of the system while ammonia oxidizing bacteria are retained along with denitrifying bacteria. This effectively stops the nitrification process at nitrite and prevents the formation of nitrate. Using this metabolic mode of operation allows for a 25% reduction in aeration energy required for nitrification and a 40% reduction in the amount of BOD required for denitrification. The separate treatment of high strength ammonia liquors significantly reduces the load on the main treatment plant, thus increasing plant capacity without the need for the construction of additional basin volume. The SHARON process is characterized by extreme process stability, due to the high growth rate of bacteria and the absence of sludge retention. The sludge retention time is equal to the hydraulic retention time, which means that no external control of the mixed liquor suspended solids concentration is required. Basically the system controls itself. The process will adjust even to strong variations in feed conditions without operator intervention and will recover from process disturbances in hours, rather than days. Full treatment capacity can be maintained even when a limited feed load is available, which allows for sudden increases in load without adverse effects on effluent quality. The system can be shut down for days without loss of treatment capacity. The process has moved beyond the development stage. Six full-scale SHARON systems have been constructed at large wastewater treatment plants in the Netherlands (located in Rotterdam, Utrecht, Zwolle, Beverwijk, Groningen and The Hague). The SHARON plants at Rotterdam and Utrecht have provided more than ten years of operational experience each. Operator experiences with these systems are discussed in the next chapter. A SHARON for New York City (USA) is operational since May 2009. SHARON systems are in preparation for Geneva (CH), Paris (F), Shell Green (Manchester, UK) and Whitlingham (Norwich, UK). The SHARON process has also been successfully tested on wastewater from the dewatering and drying of digestate from a combined manure and organic slurry digestion plant (MAV, Ghent, Belgium). This 50 m3/h wastewater flow contains high levels of ammonia and suspended solids. It was determined that the SHARON process was preferable to conventional aerobic treatment processes or treatment in a membrane bioreactor, or to non-biological treatment methods like ammonia stripping. Compared to these other processes, the SHARON process configuration was found to be technologically less complex and more flexible, and the investment and operational costs were considerably lower. General comparison of different techniques for N-removal from rejection water Production chemical sludge Production biological sludge Dosage chemicals Energy requirements Operation Cost* estimate Euro/kg N Air stripping yes no yes average average 6,0 Steam stripping yes no yes high complex 8,0 MAP/CAFR process yes no yes low complex 6,0 Membrane bioreactor no yes yes high average 2,8 Biofilm airlift reactor no low yes average average 5,7 SHARON process no low yes average average 1,5 *Cost estimate base on STOWA (1996) for WWTP capacity of 500,000 p.e. 1 The STOWA (Dutch acronym for the Foundation for Applied Water Research) coordinates and commissions research on behalf of a large number of local water administrations. Among the 61 bodies which contribute to the STOWA, there are water boards, provinces and the Ministry of Transport, Public Works and Water Management SHARON 9

2 SHARON Nitrogen Removal over Nitrite Compact systems for treatment of concentrated wastewater flows are increasingly more important, particularly where space is lacking. A new development is the SHARON (Single reactor system for High activity Ammonia Removal Over Nitrite). SHARON is a joint development of Grontmij, TU Delft and the Waterboard ZHEW. SHARON is especially fit for treatment of nitrogen rejection waters from sludge digestion, the treatment of landfill leachate and the treatment of various concentrated industrial wastewaters. Background Bacterial activity increases at high temperatures. At temperatures of 30-40 C nitrifying sludge needs only a short residence time. At these high temperatures nitrogen-rich wastewaters can be treated in a single reactor. No sludge retention is required to maintain the nitrifying sludge in the system as long as the hydraulic retention time is equal or higher than the minimum sludge retention time. SHARON (pat.) is specially fit for treatment of nitrogen-rich wastewaters, for example rejection water from the dewatering of digested sludge at a WWTP. Furthermore SHARON is also fit for pretreatment of various highly concentrated industrial wastewaters. Advantages Compared to other techniques for treatment of nitrogen-rich wastewaters like steam stripping, the MAP-process or the air lift reactor, SHARON has several advantages: low investment costs low operational costs no chemical by-products simple operation and maintenance easy start-up insensitive to high influent SS levels negligible odour emission Schematic representation of SHARON Influent NH4 NO2 Effluent NO2 N2 (Alkalinity) 30-40 C C-source Mixing Aeration SHARON 11

2 SHARON Nitrogen Removal over nitrite Results of rejection water treatment SHARON Rotterdam parameter dimension value Nkj influent mg/l 1,000-1,500 N-removal % > 95 HRToxic day 1,0-1,5 temperature C 30-40 ph - 6,8-7,2 oxygen ppm 1,0-1,5 NH 4 + NH4 + + + Nitrification 1,5 O2 2 O2 Denitrification NO2 - + H2O + 2H + NO3 - + H2O + 2H + 25% energy saved 6 NO2 - + 3CH3OH + 3 CO2 3N2 + 6 HCO3 - + 3 H2O 6 NO3 - + 5CH3OH + CO2 3N2 + 6 HCO3 - + 7 H2O 40% methanol saved In conventional aerobic systems the biological ammonia oxidation comprises of two steps. First the oxidation of ammonia to nitrite by Nitrosomonas and subsequently the oxidation of nitrite to nitrate by Nitrobacter. At higher temperatures Nitrosomonas prove to have significantly higher maximum growth rates than Nitrobacter. minimum residence time (d.) Wash-out of Nitrobacter Nitrosomas Nitrobacter 0 10 20 30 40 temperature ( C) So in a system without sludge retention they can survive at shorter residence times. In a reactor with a temperature of 30 to 40 C and a short residence time mainly ammonia oxidation to nitrite occurs because Nitrobacter is washed out of the system. Process features no sludge retention simple process nitrite route reduces up to: - 25% oxygen demand - 40% methanol requirement - 30% sludge production - 20% CO 2 emission maximum usage of alkaline buffer Application dewatering liquors from sludge digestion leachate water of landfill site wastewater of composting process condensate of sludge drying Full scale plants location: WWTP Utrecht (NL) capacity: 400,000 pe influent: filtrate N-load: 900 kg NH 4 /d operational: 1997 location: WWTP Rotterdam (NL) capacity: 470,000 pe influent: centrate N-load: 850 kg NH 4 /d operational: 1999 location: WWTP Zwolle (NL) capacity: 200,000 pe influent: centrate N-load: 410 kg NH 4 /d operational: 2003 location: WWTP Beverwijk (NL) capacity: 320,000 pe influent: centrate and condensate N-load: 1200 kg NH 4 /d operational: 2003 location: WWTP Groningen (NL) capacity 300,000 pe influent: filtrate and condensate N-load: 2500 kg NH 4 /d operational: 2005 location: WWTP Den Haag (NL) capacity: 930,000 pe influent: centrate N-load: 1200 kg NH 4 /d operational: 2005 location: New York City (US) WPCP: 250 MGD influent: centrate SHARON: 1.85 MGD 5000 kg NH 4 /d operational: 2009 location: Geneva (CH) capacity 600,000 pe influent: centrate SHARON: 1600 m 3 /d 1700 kg NH 4 /d operational: 2010 location: Seine Grésillons (F) capacity: 300,000 m 3 /d influent: centrate SHARON: 3200 m 3 /d 3500 kg NH 4 /d operational: 2012 location: MVPC Shell Green (UK) influent: centrate SHARON: 1400 m 3 /d 1600 kg NH 4 /d operational: 2010 location: Whitlingham (UK) influent: centrate SHARON: 900 m 3 /d 1500 kg NH 4 /d operational: 2010 location: Linköping (S) influent: centrate SHARON: 490 m 3 /d 500 kg NH 4 /d operational: 2009 SHARON 12 SHARON 13

3 Full-scale experience with the SHARON process......through the eyes of the operators J.W. Mulder, J.O.J. Duin, J. Goverde, W.G. Poiesz, H.M. van Veldhuizen, R. van Kempen, P. Roeleveld Abstract This paper summarizes different operating aspects and experiences of several SHARON plants. The SHARON process is suitable for treatment of high strength ammonia wastewaters such as reject water from dewatering of digested sewage sludge and wastewater from sludge drying or incineration plants. The aerated retention time and nitrite concentration are the two most important process parameters to control the ammonia outlet concentration. Ammonia removal efficiencies can be over 95%, are variable and can be targeted according to the required needs of the main WWTP and/or to minimize overall nitrogen removal costs. The process is compact and simple to operate. Depending on site specific circumstances there are different system configurations possible. Nine years of operating experience prove that the SHARON process is sustainable and highly competitive. Compared to conventional techniques there are significant savings of energy and consumables. Application of fine bubble aeration has further decreased aeration costs. Recently the use of by-products of the biofuel industry as COD source for denitrification has further increased the cost effectiveness. SHARON is successfully applied to significantly improve the main WWTP nitrogen effluent quality. It proves to be a cost effective alternative for conventional extension of the WWTP. Keywords SHARON, Nitrogen removal, nitrification, denitrification, nitrite, rejection water, side stream Figure 1 Different growth rate of ammonia and nitrite oxidizers Introduction The SHARON process was developed in the 90 s of the last century at the Delft University of Technology (Hellinga et al., 1998; Hellinga et al., 1999; STOWA, 1996). SHARON refers to Stable and High activity Ammonia Removal Over Nitrite. The process is especially suitable for high strength ammonia wastewaters. Typical applications are treatment of reject water from dewatering of digested sewage sludge (Mulder et al., 2001; Kempen et al., 2001) and wastewater from sludge drying or incineration plants. By treating reject water which is only 1% of the hydraulic load of a WWTP, the nitrogen load to a WWTP is reduced by 10 to 30%. With side stream treatment the overall nitrogen removal efficiency of the WWTP can be significantly improved. Other applications are treatment of landfill leachate and wastewater from digestion of organic waste and manure (Notenboom et al., 2002). The SHARON process makes advantage of the difference in growth rate of ammonia oxidizers and nitrite oxidizers which is illustrated in Figure 1. At higher temperatures, the ammonia oxidizers have a significant higher growth rate. By controlling the aerated retention time to approximately 1 day, the nitrite oxidizers will be washed out of the tank, and nitrification will be limited to nitrite formation. The SHARON process is operated in completely mixed reactors without sludge retention. Therefore the hydraulic retention time (HRT) is equal to the sludge retention time (SRT). A system without sludge retention behaves like a chemostat. Typically the outlet concentration of a chemostat is independent of the inlet concentration. A chemostat is therefore especially suited for treatment of high strength wastewaters. Furthermore the absence of sludge retention makes the SHARON process insensitive to suspended solids levels that may vary in reject water of sludge dewatering. Figure 2 The nitrite route Minimum aërated retention time O2 (75%) O2 (25%) Nitrobacter NH4 NO2 NO3 1 day Nitrosomonas 40% Methanol 60% Methanol temperature ( C) 35 C N2 SHARON 15

3 Full-scale experience with the SHARON process As a result of N-removal by nitrite instead of nitrate energy and COD are saved. Nitrification limited to nitrite saves 25% of aeration energy. Denitrification of nitrite saves 40% of COD, as is indicated in Figure 2 (page 11). More than 80% of the energy demand related to the treatment of high strength ammonia wastewaters is contributed to aeration energy. Therefore a 25% reduction of the aeration energy is a significant decrease of the overall energy consumption. In addition 30% less surplus sludge is produced and overall 20% less CO 2 is emitted. Figure 3 From left to right and from top to bottom: SHARON plant: Rotterdam-Sluisjesdijk, Utrecht, Zwolle, Beverwijk, The Haque-Houtrust and Groningen-Garmerwolde The advantage of a high conversion rate and the savings on consumables demand makes the SHARON process a compact and sustainable method for nitrogen removal. This paper presents from an operational perspective an overview of the different SHARON plants. Overview of sharon plants The first full scale SHARON plant came in 1997 in operation. At present six systems are implemented. In Table 1 an overview of the SHARON systems in the Netherlands is presented and Figure 3 contains a photograph of each plant. Most plants are applied for treatment of reject water from sludge dewatering. The first large scale SHARON system outside the Netherlands will be built at the WWTP New York Wards Island (Carrio, 2003). This plant will have a capacity of 5.000 kg nitrogen per day and will be operational in 2007. Figure 4 Schematic representation of a single tank SHARON system System configuration The basic configuration of SHARON process consists of a single, completely mixed tank. The tank is aerated intermittently to accommodate nitrification and denitrification (Figure 4). An alternative configuration consists of two separate tanks, one for nitrification and one for denitrification. Water is recirculated between the two compartments. An advantage of this configuration is a lower installed aeration capacity because the aeration system can operate continuously at design treatment capacity. A disadvantage however is the need for a recirculation flow which restricts the maximum denitrification efficiency and requires an extra pump. Depending on the site specific circumstances such as space restrictions, wastewater characteristics, existing available tank volume and minimum overall costs an optimum system configuration is selected. Table 2 presents the configuration and volume of the different full scale plants. Heating or cooling may be required to maintain a process temperature between 30 Celsius and 40 Celsius (86-104 F). Inlet NH4 NO2 NO2 N2 Outlet Usually an external COD source such as methanol is needed because the BOD concentration of reject water is low. Caustic can be used for additional ph control. In practice most SHARON plants operate without the use of caustic and caustic is only used as back-up facility. (Alkalinity) C-source 30-40 C Mixing Jet aerators or fine bubble diffusers are used for aeration. The first SHARON plants were equipped with jet aerators. For more recent SHARONs, material developments made application of fine bubble diffusers in warm media possible, achieving higher oxygen transfer efficiencies. The denitrification process requires mixing. Aeration Table 2 System configuration SHARON plants Table 1 - Full scale SHARON plants Netherlands SHARON In operation since Load (kg N/day) Wastewater application Utrecht 1997 900 sludge dewatering Rotterdam-Dokhaven 1999 850 sludge dewatering Zwolle 2003 410 sludge dewatering Beverwijk 2003 1,200 sludge dewatering/drying dewatering/drying The Hague-Houtrust 2005 1,300 dewatering Groningen-Garmerwolde 2005 2,400 sludge dewatering/drying SHARON Tanks Volume (m 3 ) Volume (US Gallon) Utrecht Two 3,000/1,500 792,600/396,300 Rotterdam-Dokhaven Single 1,800 475,560 Zwolle Two 900/450 237,780/118,890 Beverwijk Two 1,500/750 396,300/198,150 The Haque-Houtrust Single 2,000 528,400 Groningen-Garmerwolde Two 4,900/2,450 1,294,580/647,290 SHARON 16 SHARON 17

3 Full-scale experience with the SHARON process Aerated retention time control The nitrification is limited to nitrite formation. A key feature to obtain stable nitrite production is control of the Aerated Retention Time (ART). At a temperature of around 35 C an ART of 1-2 day is required to predominately (>98%) produce nitrite. The aeration is operated discontinuously and according to the inlet flow the length of an aeration period is adjusted accurately. A typical trend of the ART control is illustrated in Figure 5. Ammonia removal efficiency An advantage of the process is a high conversion rate at temperatures above 30 C and therefore a short ART (1-2 days) is sufficient for the nitrification process. On the other hand the Ks value (Monod kinetics) for ammonia increases with increasing growth rates. As a consequence the ammonia outlet concentration increases with shorter ARTs. As rule of thumb the ammonia outlet concentration increases from less than 5 NH 4 -N/l at an ART of 2 days to approximately 100 mg NH 4 -N/l at an ART of 1 day. At an ART of 1.5 days an ammonia outlet concentration of approximately 20 mg NH 4 -N/l can be achieved. In addition the ammonia outlet concentration depends on the nitrite outlet concentration. Originally denitrification was applied for ph control only. The SHARON Rotterdam-Sluisjesdijk plant was run with nitrite concentrations as high as 200-300 mg NO 2 -N/l. During a period with complete denitrification low outlet ammonia concentrations (< 20 mg/l) were achieved. High nitrite levels do significantly reduce the activity of ammonia oxidizers. Besides the ART and nitrite outlet concentration the process parameters ph, temperature and oxygen concentration do influence the actual outlet ammonia concentration. Increased temperatures, ph values and oxygen levels do in general increase the ammonia removal efficiency. The ammonia outlet concentration is thus variable and depends on the actual settings of the process operating parameters. Based on full scale experience the ammonia outlet concentration can be targeted according to a required ammonia removal demand and/or to minimize overall nitrogen removal costs. Figure 6 presents the nitrogen removal efficiency of SHARON Beverwijk. The average ammonia removal efficiency is 94%. Incidentally there is a shortage of COD source (sludge dryer condensate) that lowers the denitrification efficiency. Even so the average total nitrogen removal efficiency is 88%. In Table 3 the average ammonia removal results of several SHARON plants are presented. PH control Nitrification results in a ph decrease. Because of the high inlet concentrations the ph effect will be strong, and without ph correction nitrification will be inhibited. Three mechanisms can be responsible for ph adjustment. The first mechanism is stripping of CO 2. Wastewater originating from sludge digestion will contain high concentrations of CO 2. In these wastewaters the stripping effect will be responsible for neutralizing about 50% of the ph decrease. The process of CO 2 stripping cannot be controlled. The second mechanism is denitrification. A maximum of 50% of the ph effect can be neutralized by denitrification. For denitrification both external and internal COD sources are applied. Dependant on the requirements of the main WWTP full or partial denitrification can be targeted. For ph control only partial denitrification is often sufficient. In addition any outlet nitrite will be denitrified in the part(s) (head of works, primary sedimentation, first aeration etc.) of the main WWTP. The third mechanism is dosage of caustic which is the most direct way of ph control. However dosage of caustic is more expensive in comparison with denitrification with external C-sources. In practice dosage of caustic can be needed in situations where due to addition of specific chemicals such as iron chloride for dewatering, the CO 2 content of the wastewater is decreased. In these cases the CO 2 stripping effect will be less than 50% and depending on targeted nitrification efficiencies addition of caustic may be needed. Two of the six full scale SHARON plants in operation do require additional caustic dosage due to the use of ferric chloride at the dewatering. Other SHARON plants have caustic dosing systems as a backup provision. The SHARON The Haque-Houtrust plant has no caustic dosing system at all. In all situations ph measurement and control is very important for process stability. In case of a single tank system the aeration is discontinuous and the ph will vary during a cycle. The difference between the maximum and minimum ph value during a cycle can be 0.5 ph unit. A typical ph trend of single tank system is illustrated in Figure 7. Figure 5 Typical trend ART control SHARON Zwolle Figure 6 Removal efficiencies SHARON Beverwijk Figure 7 Typical ph trend SHARON The Haque-Houtrust Table 3 - Average results of different SHARON plants Location ART (day) Inlet concentration (mg NH4-N/l) NH4-N removal efficiency (%) Utrecht 1 3 6 600 900 90 95 Rotterdam 1.3 1.8 1.000 1.500 85 98 Zwolle 1.3 1.8 400 600 85 95 Beverwijk 1.3 1.8 700 900 85 95 Houtrust 1.5 1.8 900 1.200 85 98 Garmerwolde 2 1.4 1.5 700 800 95 1 Due to the ART above 2 days nitrogen is removed partly by nitrate 2 Expected results after start pre-thickening surplus sludge SHARON 18 SHARON 19

3 Full-scale experience with the SHARON process COD sources for deninitrification The BOD concentration of most ammonia rich wastewaters is very limited, e.g. wastewater from dewatering of digested sludge. In this situation an external COD source has to be dosed. The ratio of COD:N for denitrification has a stoichometric value of 2.86 in case of denitrification of nitrate and 1.71 in case of nitrite. Including sludge production the COD consumption is expected to be about 4 g COD/g NO 3 -N and 2.4 g COD/g NO 2 -N. The actual COD consumption is the best indicator for nitrification/denitrification by the nitrite route. Nitrate and nitrite effluent concentrations are of little importance because the actual ratio between production and conversion of nitrate and nitrite are unknown. Different types of COD sources are used for denitrification as is presented in Table 4. Traditionally methanol is applied as a cost effective external COD source. Methanol is not part of the natural citric acid cycle breakdown pathway and therefore denitrifying bacteria need some adaptation time. In full scale practice the observed adaptation time is short and amounts to less than several days. The use of methanol requires safety measures for storage and dosing, due to fire and explosive risks. Plants that use methanol do investigate the feasibility of using alternative COD sources. Alternative COD sources such as industrial waste products can be used as well. Issues for use of industrial waste products are residuals such as heavy metals, continuity of delivery and COD concentration. A high COD concentration is important in order to avoid significant decrease of the hydraulic retention time due to dilution. The application of industrial waste products is not very common yet. Recently byproducts from the rapid growing biofuel production industry have become widely available as external COD source. These products can be 2-4 times more cost effective than high grade methanol and may require less stringent storage measures. Usually existing storage and dosing facilities for methanol can be used. Some SHARON plants treat a mixture of wastewater from dewatering of digested sludge and wastewater (condensate) from sludge drying. Wastewater from sludge drying is COD rich and therefore no or less external COD source is needed. In practice the SHARON plants have a COD:N ratio below 2.4 gram COD per gram nitrite removed. SHARON Utrecht has a COD:N ratio of 3.0. The ART of this plant is above 2 days and therefore partially nitrate besides nitrite is produced by nitrification Temperature control Biological processes produce heat. As a consequence the heat production of the high strength wastewaters is significant. As rule of thumb nitrogen removal (nitrification/denitrification) by nitrite produces 10 C temperature increase per 1 gram ammonia per liter. A temperature of 35 Celsius (95 F) is used as design temperature. In practice the process functions well within a range of 30 to 40 Celsius (86-104 F). In full scale practice even maximum temperatures of 42 Celsius (108 F) were reached. Temperature control is therefore not a very critical factor. For each plant a detailed heat balance is made. Most dominant factors are wastewater temperature, inlet ammonia concentration and tank insulation. Figure 8 illustrates a heat balance of the SHARON Rotterdam-Sluisjesdijk plant. A system without cooling/heating equipment is preferable because of its simplicity. The SHARON plant The Haque- Houtrust has no heating or cooling system. Here the system temperature varies over season between 34 and 42 Celsius (93 108 F). On other locations depending on site specific circumstances cooling or heating can be required. At sites with sludge drying, the condensate can have temperatures up to 70 Celsius (158 F) and thus cooling is necessary. Locations with relatively low wastewater temperatures (below 25 Celsius (77 F)) and low inlet concentrations (below 700 mg NH 4 -N/l) may require additional heating. In many occasions excess heat and/or biogas are available for additional heating. Sludge dewatering Sludge dewatering operation can have a significant effect on both inlet temperatures and inlet concentrations. For example in case of a belt filter press the belt press water (filtrate) should preferably be collected separately from the belt pres rinse water as is illustrated in Figure 9. The filtrate can be reused as belt rinse water. Additionally the used belt press rinse water can be added to the sludge input to remove suspended solids. In case fresh water is used as belt pres rinse water the filtrate is unnecessarily cooled and diluted. Also filtrate can be used to dilute the Poly Electrolyte (PE) base solution and can be subject of optimization. Optimum sludge thickening prior to digestion is another factor of importance to reach high inlet concentrations and does improve the effectiveness of digestion and side stream treatment in general. Large uncovered digested sludge storage tanks should be avoided to prevent unnecessary cooling. Finally the use of specific anti-foam agents prior to the SHARON process can have a negative effect on oxygen transfer efficiency of the aeration. In case an anti-foam agent is needed, a suitable product should be carefully selected depending on site specific wastewater characteristics and circumstances. In general the SHARON processes are operated without the additional use of anti-foam agents. Table 4 Different COD sources used for denitrification Figure 8 Heat balance SHARON Rotterdam-Sluisjesdijk Figure 9 Reuse of belt press water (filtrate) as belt rinse water Location COD source Utrecht by-product from biofuel production Rotterdam-Sluisjesdijk methanol 1 Zwolle by-product from biofuel production Beverwijk condensate sludge drying Houtrust methanol Groningen-Garmerwolde condensate sludge drying; industrial waste product; methanol 1 Use of methanol is stopped due to start-up of Anammox SHARON 20 SHARON 21

3 Full-scale experience with the SHARON process Process stability and control The definition of process stability depends on the required ammonia outlet concentration. For example the ammonia outlet concentration of SHARON Rotterdam-Sluisjesdijk may amount to about 100 mg/l. Here this outlet concentration is sufficiently low for the main WWTP. Other SHARON plants do reach lower ammonia outlet concentrations, even as low as 20 mg/l. To continuously achieve low ammonia outlet concentrations advanced process control is needed. These systems are therefore not only equipped with an oxygen, ph and temperature sensor but also with an online ammonia sensor and online nitrite sensor to enable a more advanced process control program. In full scale practice the supply of reject water can be interrupted due to a discontinuous operation of the dewatering facility during for example weekends or maintenance periods. During these periods, that may last several days or longer, the actual ammonia removal capacity is preserved. This is achieved by restriction of the aeration. Without the availability of oxygen the activity of the nitrite oxidizers is preserved and full capacity remains standby. The high process temperature and thus the high growth rate of the ammonia oxidizers, contributes to the high process stability of the SHARON process. In addition the high process temperature enables during start-up a capacity increase of up to 50% per day. All SHARON plants operate automatically. In full scale practices normal operation activities are restricted to less than 1 hour per day. Table 5 Model results effect of SHARON on WWTP nitrogen removal efficiency Operational costs The main operational costs are for energy and COD source. Costs for the COD source are strongly influenced by the type of COD source used. COD from condensate from sludge drying is available for free. Application of industrial waste streams as COD source can even be a source of income. The use of byproducts from the production of biofuel can be up to four times more cost effective than the use of a high grade methanol. Expressed per kg nitrogen removed the SHARON process is highly competitive with other techniques for removal of high strength wastewaters. Improved WWTP effluent quality The effect of SHARON on the main WWTP nitrogen effluent quality was previously described (Kempen et al., 2005). For two large WWTPs (Utrecht and Rotterdam-Dokhaven) the nitrogen balance was studied. The balances show the external and internal nitrogen loads before and after side stream treatment implementation. In both cases, implementation of SHARON significantly improved the overall WWTP nitrogen removal efficiency and nitrogen effluent quality. Three situations can be distinguished where SHARON is effective; (i) a limited aeration capacity, (ii) a limited denitrification capacity and (iii) a limited aerobic sludge age. It was shown that SHARON is successfully applied in the first and second situation. Based on model study and supported by full scale practice it was shown that in case SHARON is combined with enhanced suspended solids removal, the aerobic sludge age can be extended to maintain nitrification at lower temperatures. In the example the critical temperature for nitrification could be lowered with several degrees Celsius. In Table 5 an overview of the model results of the effect of SHARON on the WWTP nitrogen effluent quality is presented. In full scale practice the following improvements were achieved. At WWTP Rotterdam-Dokhaven, aeration capacity of the activated sludge system was limiting. Nitrogen balance Activated sludge process (AS) without SHARON AS with SHARON Limited aeration capacity Limited denitrification capacity Limited aerobic sludge age TN load Raw influent 100 100 100 100 Rejection water 20 20 20 1 N removal AS Nitri/Deni 72 72 0 72 Surplus sludge 4 4 4 4 SHARON - - - 19 Total 76 76 4 95 Effluent load TKN 21 2 96 2 NO 3 -N 3 22 0 3 TN 24 24 96 5 By implementation of SHARON the effluent ammonia load was decreased by approximately 50%. At WWTP Utrecht the denitrification capacity was the limiting factor. After implementation of SHARON the overall TN removal efficiency increased from 65% to over 75%. In both situations the improved overall nitrogen removal results were achieved even with a 6% increase of the WWWP influent nitrogen load. At both locations SHARON did improve the WWTP effluent quality and made compliance with nitrogen removal requirements possible. SHARON proved to be a cost effective alternative for conventional extension of the WWTP. Conclusions Nine years of operating experience prove that SHARON is an economic and sustainable process for nitrogen removal of high strength wastewaters. Compared to conventional techniques there is a significant saving of energy and consumables. The process is compact and simple to operate. Depending on site specific circumstances, different system configurations are possible. The process can be operated very stable. The aerated retention time and nitrite concentration are the two most important process parameters to control the ammonia outlet concentration. The process temperature is less critical and may vary between 30 and 40 C. Ammonia removal efficiencies can be over 95%, are variable and can be targeted according to the required needs of the main WWTP and/or to minimize overall nitrogen removal costs. The SHARON process is highly competitive with other techniques for removal of high strength wastewaters. Application of fine bubble aeration has further decreased aeration costs. Recently the use of by-products of the biofuel production industry as COD source for denitrification, has further increased the cost effectiveness. SHARON is successfully applied to improve the main WWTP nitrogen effluent quality. It proves to be a cost effective alternative for conventional extension of the WWTP. Acknowledgments The authors of this paper like to thank the Delft University of Technology and the STOWA (the Dutch foundation of Applied Water Research) for their support and contribution to the development of the SHARON process. End notes J.W. Mulder is employee of the Hollandse Delta Water Board, J.O.J. Duin is employee of the De Stichtse Rijnlanden Water Board, J. Goverde is employee of the Hollands Noorderkwartier Water Board, W.G. Poiesz is employee of the Noorderzijlvest Water Board, H.M. van Veldhuizen is employee of the Groot Salland Water Board, and R. van Kempen and P. Roeleveld are employees of the Grontmij Nederland Consulting Engineering Company. Mixing and Mass transfer Technologies INC, Lotepro Environmental Systems and Services is the licensee from Grontmij of the SHARON process in North America. Please address all communications regarding SHARON to Alphonse Warakomski by e-mail at: awarakomski@m2ttech.com References Abma, W, (2006), J.W. Mulder, W. v.d. Star, M. Strous, (2006), Anammox in Rotterdam overtreft verwachtingen (in Dutch), H 2 O, 10, pp 47-49. Carrio, L, J. Sexton, A. Lopez, K. Gopalakrishnam, V. Sapienza, (2003), Ammonia-Nitrogen Removal from Centrate, 10 years of testing and operating experience in New York City, WEFTEC 2003 - Session 42: Municipal Wastewater Treatment Processes, Water Environment Federation, 2003. Dongen, U. van, Jetten, M.S.M. & van Loosdrecht, M.C.M. (2001). The SHARON Anammox process for treatment of ammonium rich wastewater. Wat. Sci. Tech. 44 (1), pp 153-160. Hellinga, C., M.C.M. van Loosdrecht, J.J. Heijnen, (1999). Model based design of a novel process for nitrogen removal from concentrated flows. Math. Comp. Modell. Dyn. Sys. 5, pp 1-13. Hellinga, C., A.A.J.C. Schellen, J.W. Mulder, M.C.M. van Loosdrecht and J.J. Heijnen, (1998). The SHARON process; An innovative method for nitrogen removal from ammonium rich waste water. Wat. Sci. Tech. 37, pp. 135-142. Kempen, R. van, J.W. Mulder, C.A. Uijterlinde and M.C.M. Loosdrecht, (2001). Overview: full scale experience of the SHARON process for treatment of rejection water of digested sludge dewatering. Wat. Sci. Tech., 44 (1), pp 145-152, IWA Publishing 2001. Kempen, R. van, C.C.R. ten Have, S.C.F. Meijer, J.W. Mulder, J.O.J. Duin, C.A. Uijterlinde and M.C.M. van Loosdrecht, (2005). SHARON process evaluated for improved wastewater treatment plant effluent quality. Wat. Sci. Tech., 52 (4), pp 55-62, IWA Publishing 2005. Mulder, J.W., M.C.M. van Loosdrecht, C. Hellinga and R. van Kempen, (2001). Full-scale application of the SHARON process for treatment of rejection water of digested sludge dewatering. Wat. Sci. Tech., 43 (11), pp 127-134, IWA Publishing 2001. Notenboom, G. J., J.C. Jacobs, R. van Kempen, M.C.M. van Loosdrecht, (2002) High rate treatment with SHARON process of waste water from solid waste digestion, IWA, 3rd International Symposium Anaerobic Digestion of Solid Wastes, 18 to 20 September 2002 Munich / Garching, Germany. STOWA (1996). Treatment of nitrogen-rich return flows of sewage treatment plants. Single reactor system for removal of ammonium over nitrite (in Dutch). STOWA report 96-01. SHARON 22 SHARON 23

4 Reference list Project SHARON Seine Grésillons, Paris, France Client OTV on behalf of Syndicat Interdepartemental pour l Assainissement de l Agglomeration Parisienne (SIAAP). Capacity 3200 m3/day, Ammonia removal 3500 kg/day Year Under design (construction starts 2010) Description A system for the treatment of nitrogen rich wastewater (centrate and condensate) produced during dewatering of digested sludge and sludge drying. Contracting method used Services contract for design, start-up and commissioning, including process guarantees. Project SHARON STEP Aire II, Genève, Switzerland Client Service Industriels de Genève (SIG) Capacity 1600 m3/day, Ammonia removal 1700 kg/day Year Under design (construction starts 2009) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. Contracting method used Services contract for design, start-up and commissioning, including process guarantees. Project SHARON Whitlingham STC, Norwich, UK Client Black & Veatch on behalf of Anglian Water Capacity 900 m3/day, Ammonia removal 1500 kg kg/day Year Under design (construction starts 2009) Description A system for the treatment of nitrogen rich wastewater (filtrate) produced during dewatering of digested sludge. The sludge treatment system includes a thermal hydraulysis process prior to digestion, yielding highly concentrated dewatering liquors. Contracting method used Services contract for design, start-up and commissioning, including process guarantees. Project SHARON Shell Green, Mersey Valley Processing Centre, Widnes (near Manchester), UK Client S3JV on behalf of United Utilities Capacity 1400 m3/day, Ammonia removal 1600 kg/day Year Under design (construction starts 2009) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. Shell Green is the central sludge processing centre for Manchester and Leeds. Contracting method used Services contract for design, start-up and commissioning, including process guarantees. Project SHARON Linköping, Sweden Client Tekniska Verken i Linköping AB Capacity 490m 3 /day, Ammonia removal 500 kg/day Year 2009 (operational) Description A system for the treatment of nitrogen rich wastewater (centrate produced during dewatering of digested sludge) Contracting method used Turnkey (refurbishment of existing SBR) SHARON 25

4 Reference list Project SHARON WPCP Wards Island, New York City, USA Client Metcalf & Eddy of New York, Inc. / New York City Department of Environmental Protection Capacity 7000 m3/day, Ammonium removal 5000 kg per day. Year 2008 2009 (Under construction) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. The capacity of WPCP Wards Island is 285 MGD. The SHARON system is currently under construction. Contracting method used SHARON Systems LLC, a joint Grontmij/M2T company, is responsible for design, supply and installation of mechanical and electrical equipment, commissioning and one year operation assistance. Project SHARON WWTP Garmerwolde, The Netherlands Client Waterboard Noorderzijlvest Capacity 3200 m3/day, Ammonium removal 2500 kg per day. Year 2005 (operational) Description A system for the treatment of nitrogen rich wastewater (centrate and condensate) produced during dewatering of digested sludge and sludge drying. The capacity of WWTP Garmerwolde is 300,000 p.e. Contracting method used Grontmij was responsible for Turnkey realisation. Project SHARON WWTP Rotterdam-Dokhaven, The Netherlands Client Waterboard Hollandse Eilanden en Waarden Capacity 600 m3/day, Ammonium removal 850 kg per day. Year 1997-1998 (Operational) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. The capacity of WWTP Rotterdam-Dokhaven is 470,000 p.e. Contracting method used Grontmij was responsible for design, preparation of tender documents, construction supervision and commissioning. Project SHARON WWTP Utrecht, The Netherlands Client Water Authority De Stichtse Rijnlanden Capacity Ammonium removal 900 kg per day. Year 1997 (Operational) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. The capacity of WWTP is 400,000 p.e. Contracting method used Grontmij was responsible for Turnkey realisation. Project SHARON WWTP Houtrust, The Hague, The Netherlands Client Delfluent Services bv / Waterboard Delfland Capacity 900 m3/day, Ammonium removal 1200 kg per day. Year 2005 (operational) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. The capacity of WWTP Houtrust is 930,000 p.e. Contracting method used Grontmij was responsible for Turnkey realisation. Project SHARON WWTP Beverwijk (The Netherlands) Client Waterboard Uitwaterende Sluizen Capacity 900 m3/day, Ammonium removal 1200 kg per day. Year 2002-2003 (Operational) Description A system for the treatment of nitrogen rich wastewater (centrate and condensate) produced during dewatering of digested sludge and sludge drying. The capacity of WWTP Beverwijk is 326,000 p.e. Contracting method used Grontmij was responsible for design, preparation of tender documents, and commissioning. Project SHARON WWTP Zwolle, The Netherlands Client Waterboard Groot Salland Capacity 600 m3/day, Ammonium removal 410 kg per day. Year 2001-2003 (Operational) Description A system for the treatment of nitrogen rich wastewater (centrate) produced during dewatering of digested sludge. The capacity of WWTP Zwolle is 200,000 p.e. Contracting method used Grontmij was responsible for design, preparation of tender documents, construction supervision and commissioning. SHARON 26 SHARON 27

SHARON Linköping (SE) At the wastewater treatment plant in Linköping an existing sequencing batch reactor for treatment of digested sludge liquors is refurbished into a SHARON reactor. The municipal wastewater treatment plant of Linköping is operated by Tekniska Verken. The primary and secondary sludges that are produced on site are digested and the digested sludge is dewatered in centrifuges. Previously the digested sludge liquors were treated in a sequencing batch reactor prior to return to the main works, using a conventionel activated sludge system. Refurbishment of the liquor treatment plant was required to increase the capacity of the system and to achieve better process stability, Tekniska Verken has selected the SHARON process for nitrogen removal over nitrite as the prefered method of liquor treatment. Grontmij Sweden was responsible for construction. The process design was supplied by Grontmij Nederland. Location Sweden Clients Tekniska Verken Period 2009-2009 Characteristics SHARON: 490m3/day 610 kg/day NH 4 Influent: Centrate N-removal: >96% Operational: 2009 SHARON 29

SHARON Seine Grésillons (F) OTV, in a joint venture with Bouygues Traveaux Publics, has been selected by SIAAP (Syndicat Interdépartmental pour l Assainissement de l Agglomeration Parisienne) for the extension of the wastewater treatment plant Seine Grésillons. The project will triple the capacity of the plant to 300,000 m3/day and will add sludge digestion, dewatering and drying to the process. OTV have selected the SHARON process for treatment of dewatering liquors and condensate from the sludge dryer. The SHARON system will have a capacity of 3200 m3/day and will remove 3500 kg/day of ammonia. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy; denitrification of nitrite saves 40% on BOD addition; denitrification of nitrite at high temperatures reduces sludge production by 50%; simple process with high process stability. Grontmij, as a subcontractor to OTV, is responsible for process design and commissioning. The SHARON process will come into operation in 2012. Location France, Paris region Clients OTV on behalf of SIAAP Period 2008-2010 Characteristics SHARON: 3200m 3 /day 3500 kg/day NH 4 Influent: Centrate N-removal: >96% Operational: 2012 SHARON 31

SHARON Geneva (CH) Geneva (Switzerland) has selected the SHARON process for nitrogen removal for the extension of the wastewater treatment plant Aïre 2. SHARON is a proprietary technology developed by Grontmij. In a joint project team with the client, Grontmij is responsible for process design, preliminary design, process control and automation systems, and assistance with start-up and operation. The plant will be operational in 2010. The wastewater treatment plant Aïre 2 at Geneva is one of the three largest wastewater treatment plants in Switzerland. The capacity amounts to 600,000 population equivalents at a maximum hydraulic capacity of 18.000 m3/h. The plant discharges the treated wastewater of the city of Geneva into the river Rhône. SIG has selected the SHARON process in an extensive system selection procedure, including a technological evaluation and additional site visits in the Netherlands and Austria. SHARON is selected for reasons of proven process stability, flexibility, robustness of operation and the competitive investment and operational costs. Currently the plant fails to meet standards for nitrogen removal during the winter period. Supplementary treatment capacity is necessary, also because of an expected increase in load in the near future. Services Industriels de Genève (SIG; the public utility of Geneva) has evaluated a number of specific nitrogen removal systems and has selected the SHARON technology of Grontmij as the best available technology. The construction of the SHARON system is part of an extension program for the total treatment plant. SIG Location Switzerland Geneva Clients Services Industriels de Genève (SIG ) Period 2007-2010 Characteristics WWTP: 600,000 p.e. SHARON: 1600m 3 /day 1700 kg/day NH 4 Influent: Centrate N-removal: >95% Operational: 2010 SHARON 33

SHARON Whitlingham STC (UK) The SHARON Liquor Treatment Plant forms part of Anglian Water s Bio-solids capital programme with particular regard to their Whitlingham STC (Sludge Treatment Centre) upgrade scheme. The overall bio-solids project at Whitlingham comprises the upgrading of the existing sludge treatment plant to provide increased capacity. The processed sludge is to be treated to ADAS Enhanced Treatment Standards. A consequence of increasing the sludge treatment capacity and the degree of treatment is that the associated liquor flow and loads will also increase to the detriment of the works discharge consent standards. There is a need therefore, to install a new Liquor Treatment Plant (LTP), to reduce the aqueous ammonia concentrations contained in the liquors. Following a detailed appraisal of available process options, including the undertaking of Risk & Value Intervention (R&VI) analysis; the Grontmij SHARON (Stable High Ammonia Removal Over Nitrite) process is the preferred selection for the Whitlingham STC site. SHARON will achieve a removal efficiency of 96% Grontmij, as a subcontractor to Black &Veatch Ltd, is responsible for process design and commissioning. The SHARON process will come into operation in 2010. The return liquors to be treated in the LTP arise from the post-digestion dewatering. Upstream feed sludges to the digesters are first processed within a thermal hydrolysis (CAMBI) plant prior to anaerobic digestion at the mesophilic level. THP results in enhanced biodegradability of sludge in the digestors. As a consequence ammonia concentrations in the dewatering liquors will be in the range of 2000 to 3000 mg/l. Location United Kingdom Norwich Clients Black & Veatch Ltd on behalf of Anglian Water Period 2008-2010 Characteristics SHARON: 900m 3 /day 1500 kg/day NH 4 Influent: Centrate N-removal: >96% Operational: 2010 SHARON 35

SHARON MVPC Shell Green (UK) United Utilities has selected the SHARON process for removal of nitrogen from centrate at the MVPC (Shell Green) centre for sludge processing. Grontmij, as a subconractor to S3JV, is responsible for process design and commissioning. The MVPC (Shell Green) is United Utilities regional dewatering and incineration centre, located in the Mersey Valley near Widnes. The existing works comprises of sludge dewatering and two streams of incineration. As part of a major extension project, the Veolia Water / Costain; Stream Three Joint Venture (S3JV) have been appointed by United Utilities to design and construct a third incineration stream, along with the replacement of the existing dewatering process and various ancillary plant and equipment necessary for the operation of the new stream. The increase in dewatering capacity will lead to an increase in the load of ammonia discharged with centrate. United Utilities have been informed by the Environmental Agency that a proportion of the centrate will have to be treated to remove ammonia. After pilot trials on site, United Utilities have selected the SHARON process as the prefered method of centrate treatment. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy denitrification of nitrite saves 40% on BOD addition denitrification of nitrite at high temperatures reduces sludge production by 50% simple process with high process stability. Grontmij, as a subcontractor to S3JV, is responsible for process design and commissioning. The SHARON process will come into operation in 2010. Location United Kingdom Widnes Clients Stream Three Joint Venture (Veolia, Costain) on behalf of United Utilities Characteristics SHARON: 1400m 3 /day 1600 kg/day NH 4 Influent: Centrate N-removal: >96% Operational: 2010 Period 2008-2010 Partner(s) Grontmij Ltd. (UK) SHARON 37

SHARON New York (USA) New York City has developed a Comprehensive Nitrogen Management Plan to reduce the aggregate effluent nitrogen loading from Water Pollution Control Plants (WPCPs) to the Upper East River and Jamaica Bay. Separate centrate treatment has been identified as an integral part of this plan, since up to 40% of nitrogen loading at WPCPs with centralized dewatering facilities is directly attributable to centrate loading. Pilot research by the New York City Department of Environmental Protection related to nitrogen removal and other related operational issues, showed SHARON to demonstrate significant potential as a highly efficient, cost effective and environmentally sound process for the removal of high levels of nitrogen from centrate. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has several advantages: oxidation to nitrite saves 25% on aeration energy; denitrification of nitrite saves 40% on BOD addition; denitrification of nitrite at high temperatures reduces sludge production by 50%; simple process with high process stability. Under the Management Plan, New York City has built a demonstration plant for the SHARON system at Wards Island WPCP. This SHARON will treat centrate produced at the plant in the sludge dewatering facility. This facility dewaters anaerobically digested sludge produced at Wards Island and at two other WPCPs. Grontmij, who is the owner of the proprietary SHARON technology, is responsible for design, commissioning and process start-up. The SHARON for Wards Island WPCP, with a capacity of 5000 kg NH 4 -N per day, will be operational in 2009. New York City considers it prudent to evaluate this innovative, yet proven, technology at demonstration scale to determine its applicability as part of the long term nitrogen reduction plan for New York City and to verify the potential cost savings as a result of implementation of this process. Location United States New York Clients NYCDEP Period 2003-2009 Characteristics WPCP: 250 MGD SHARON: 1.85 MGD 5000 kg NH 4 /day Influent: Centrate N-removal: >95% Operational: 2009 SHARON 39

SHARON Garmerwolde (NL) The wastewater treatment plant (WWTP) at Garmerwolde (Groningen, The Netherlands) is refurbished to meet future effluent standards. Part of the refurbishment is the construction of a SHARON system for treatment of flows produced at the sludge dewatering and sludge drying facilities at Garmerwolde. At WWTP Garmerwolde locally produced sludge is anaerobically digested and, together with sludge imported from other facilities, dewatered and dried. The filtrate produced in the sludge dewatering process together with the condensate produced in the sludge drying process contribute approximately 34% of the total nitrogen load to WWTP Garmerwolde. The Waterboard Noorderzijlvest, who owns WWTP Garmerwolde, has selected the SHARON process as preferred method for filtrate and condensate treatment on the basis of overall treatment cost, high guaranteed ammonia removal efficiency, stable operations and proven track record. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has several advantages: oxidation to nitrite saves 25% on aeration energy; denitrification of nitrite saves 40% on BOD addition; denitrification of nitrite at high temperatures reduces sludge production by 50%; simple process with high process stability. Grontmij, as main contractor and owner of the proprietary SHARON technology, was responsible for the design and construction of the SHARON system and operated the SHARON for one year. Location Netherlands Groningen Clients Waterschap Noorderzijlvest Period 2004-2006 Characteristics WWTP: 300,000 p.e. SHARON: 2500 kg NH 4 /day Influent: Filtrate and condensate N-removal: >95% Operational: 2005 SHARON 41

SHARON The Hague (NL) Under European regulation, The Netherlands is required to achieve an overall nitrogen removal efficiency of 75% in 2006 for urban wastewater. The wastewater treatment plant Houtrust at The Hague, with a capacity of 930,000 population equivalents, is a significant contributor to nitrogen discharge in The Netherlands. WWTP Houtrust has been refurbished to meet European nitrogen removal standards in 2008. To decrease the nitrogen load in the effluent in the period up to 2008, the Waterboard Delfland, together with its private operating partner Delfluent, has selected the SHARON process for centrate treatment. The SHARON process was selected for its proven nitrogen removal efficiency, low operating and construction cost and proven process stability. Grontmij has constructed the SHARON process at WWTP Houtrust as a turnkey project, with guarantees to have the system available within six months of the contract execution date. SHARON is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy denitrification of nitrite saves 40% on BOD addition reduces sludge production by 30% reduces CO 2 -emission by 20% simple process with high process stability Location Netherlands The Hague Clients Delfluent Services bv Period 2004-2006 Characteristics WWTP: 930,000 p.e. SHARON: 1200 kg NH 4 /day Influent: Centrate N-removal: >95% Operational: 2005 SHARON 43

SHARON Beverwijk (NL) New legislation for N-removal required optimisation of the Beverwijk WWTP. The Hoogheemraadschap Hollands Noorderkwartier (HHNK) is responsible for the treatment of wastewater in the region north of Amsterdam. Wastewater sludge produced at the WWTP s in the region of the Hoogheemraadschap Hollands Noorderkwartier is dried at a central location situated next to Beverwijk WWTP. The condensate produced during the drying process is nitrogen rich and discharged to the Beverwijk WWTP. A study of the N-balance of the WWTP showed that a significant fraction of the nitrogen is recirculated from the sludge digestion (so-called rejection water) towards the activated sludge tanks. Together with the condensate of the drying process this amounts to 30% of the total N-load of the WWTP. Removing this load will directly result in a significant decrease of the total N-load in the effluent. Several techniques for treatment of the rejection water were evaluated, including lab test and pilot tests at large wwtp s. This research was initiated by STOWA (the Dutch foundation for Applied Water Research). The SHARON (pat.) process pointed out to be the most cost-effective technique. SHARON has been originally developed at the Technical University of Delft (TUD). It concerns a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy; denitrification of nitrite saves 40% on BOD addition; denitrification of nitrite at high temperatures reduces sludge production by 50%; simple process with high process stability. After successful laboratory tests it was decided to design and construct a full scale process without performing an intermediate pilot test. Grontmij designed the system, assisted the Water Authority with the selection of a general contractor and with construction supervision and is responsible for process commissioning. The SHARON system of Beverwijk WWTP is operational since 2003. The implementation of SHARON resulted in an overall 2% nitrogen discharge reduction of the total area serviced by the Hoogheemraadschap Hollands Noorderkwartier. Location Netherlands Beverwijk Clients Water Authority HHNK (NL) Period 2002-2003 Characteristics WWTP: 320,000 p.e. SHARON: 1200 kg NH 4 /day Influent: rejection water and condensate N-removal: >95% Operational: 2003 Partner(s) TUD SHARON 45

SHARON Zwolle (NL) The Groot Salland Water Board has constructed a SHARON (pat.) reactor for the purpose of sidestream treatment at the sludge treatment site of the WWTP Zwolle. Grontmij was responsible of the system design and specifications. The sludge dewatering plant in Zwolle processes more than half of the sludge produced in the area managed by the Groot Salland Water Board. The sludge, which is digested at various locations, is dewatered by means of 2 centrifuges. This partial flow with a nitrogen concentration of approximately 700 mg N/l represents a daily nitrogen load of 15 to 20% of the nitrogen supply at the sewage treatment plant. WWTP Zwolle was unable to cope with the discharge of untreated centrate without refurbishment of the main plant. The Water Board is required to achieve a 75% nitrogen removal efficiency in the service area. Several different centrate treatment systems were examined and compared. On the basis of qualitative and quantitative considerations, a SHARON reactor was chosen (Stable High activity Ammonia Removal Over Nitrite). Grontmij was responsible for the preliminary design, detailed design and tender specifications.the plant is operational since 2003. It contributes to improved nitrogen removal at the WWTP Zwolle and in the area controlled by the Groot Salland Water Board. Location Netherlands Zwolle Clients Waterboard Groot Salland Period 2002-2003 Characteristics WWTP: 200,000 p.e. SHARON: 600m 3 /day 410 kg/day NH 4 Influent: Centrate N-removal: >93% Operational: 2003 SHARON 47

SHARON Rotterdam (NL) New legislation for N-removal required optimisation of the Dokhaven WWTP of Rotterdam. This WWTP was designed as a two-stage process. The two-stage process is well suitable for BOD (Biological Oxygen Demand) removal as well as nitrification. However denitrification in the second stage is poor due to BOD shortage and a high sludge loading rate. A study of the nitrogen balance of the WWTP showed that a significant fraction of the nitrogen is recirculated from the sludge digestion (so-called rejection water) towards the activated sludge tanks. This amounts to 15% of the total N-load of the WWTP. Therefore removing this load will directly result in, at least, an equivalent decrease of the total nitrogen load in the effluent. Several techniques for treatment of the rejection water were evaluated, including lab tests and pilot tests at large wwtp s. This research was initiated by STOWA (the Dutch foundation for Applied Water Research). The SHARON (pat.) process pointed out to be the most cost-effective technique. It is a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy; denitrification of nitrite saves 40% on BOD addition; nitrogen removal at high temperature reduces biological sludge production by 50%. compact and simple process. SHARON has been developed at the Delft University. After successful laboratory tests it was decided to design and construct a full scale process without performing an intermediate pilot test. Grontmij in co-operation with the Water Authority ZHEW did the detailed full-scale process design. Because there was no area available for extension a post-thickener had to be taken out of operation and was converted into a SHARON reactor. The SHARON system has been successfully in operation since 1999. Since the implementation of SHARON the total nitrogen effluent load of the Dokhaven WWTP dropped by over 30%. As a result ZHEW was able to meet the required N-removal demands. Location Netherlands Rotterdam Clients Water Authority ZHEW Period 1995-1999 Characteristics Capacity: 470,000 pe Influent: rejection water N-load: 830 kg/day N-removal: >95% Operational: since 1999 Partner(s) TU Delft and STOWA SHARON 49

SHARON Utrecht (NL) New legislation for N-removal required optimisation of the Utrecht WWTP which is operated by the Water Authority HDSR. This WWTP was designed as a two-stage process. This two-stage process is suitable for BOD (Biological Oxygen Demand) removal, nitrification and denitrification. However denitrification in the second stage is poor due to BOD shortage and a high sludge loading rate. A study of the N-balance of the WWTP showed that a significant fraction of the nitrogen is recirculated from the sludge digestion (so-called rejection water) towards the activated sludge tanks. This amounts to 15% of the total N-load of the WWTP. Removing this load will directly result in a significant decrease of the total N-load in the effluent. Several techniques for treatment of the rejection water were evaluated, including lab test and pilot tests at large wwtp s. This research was initiated by STOWA (the Dutch foundation for Applied Water Research). The SHARON process pointed out to be the most cost-effective technique. SHARON has been originally developed at the Technical University of Delft (TUD). It concerns a high active process for N-removal operating without sludge retention. Due to differences in growth rate nitrite oxidisers are washed out of the system while ammonia oxidisers can be maintained, resulting in N-removal over nitrite instead of nitrate. N-removal with SHARON via nitrite has the following advantages: oxidation to nitrite saves 25% of the aeration energy denitrification of nitrite saves 40% on BOD addition denitrification of nitrite at high temperatures reduces sludge production by 50% simple process with high process stability After successful laboratory tests it was decided to design and construct a full scale process without performing an intermediate pilot test. Grontmij designed, built and commissioned the SHARON plant of WWTP Utrecht. The SHARON system has been successfully in operation since 1999. Since the implementation of SHARON the total nitrogen discharge load of the Utrecht WWTP dropped by 30%. As a result the Water Authority HDSR can meet the strict nitrogen discharge standards. Location Netherlands Utrecht Clients Water Authority HDSR (NL) Period 1996-1997 Characteristics WWTP: 400,000 p.e. SHARON: 900 kg/day NH 4 Influent: Filtrate N-removal: >95% Operational: 1997 Partner(s) TUD and STOWA SHARON 51

Contact Henk Wim de Mooij Project Manager SHARON E henkwim.demooij@grontmij.nl T +31 30 220 78 75 When Grontmij N.V. was founded in 1915, its vision was sustainable land consolidation and reclamation for the agricultural sector and the development of the rural areas. Almost a century later, the company has developed and grown, but it is essentially the same: Grontmij creates value for its customers and shareholders by designing and realising sustainable living and working environments. Grontmij s mission is to be the best local service provider for design, consultancy, management, engineering and contracting in the environmental, water, energy, building, industry and transportation sectors. We aim to achieve this through the design and realisation of plans for the future together with the people and parties in our regions. Grontmij creates value for its customers and shareholders by designing and realising sustainable living and working environments. SHARON 53

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