ANAEROBIC BIOTRANSFORMATION & METHANE GENERATION POTENTIAL OF CHEESE WHEY IN BATCH AND UASB REACTORS. by GÖKSEL N. DEMİRER

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1 ANAEROBIC BIOTRANSFORMATION & METHANE GENERATION POTENTIAL OF CHEESE WHEY IN BATCH AND UASB REACTORS by GÖKSEL N. DEMİRER

2 Why current trend in treatment of industrial and agro-industrial wastewaters towards ANAEROBIC BIOTECHNOLOGY? Development of advanced anaerobic reactor designs with effective biological solids retentions SRT values times longer than HRT significant decrease in required reactor volume significant decrease in capital costs Turkish German Symposium - Recent Advances in Wastewater Treatment switch from conventional aerobic to anaerobic treatment systems

3 CHEESE WHEY Protein and lactose rich byproduct of cheese industry Biodegradable (~ 99%) High organic content (up to 70g COD/L) Low alkalinity (50 meq/l or 2500 mg/l as CaCO 3 ) Be reprocessed into valuable products; As protein & lactose in dairy industry As animal feed

4 ANAEROBIC TREATMENT OF CHEESE WHEY Advantages * Not require any oxygen supplementation * Significant amount of energy generation (as in conventional aerobic biological treatment) (in the form of methane gas)

5 ANAEROBIC TREATMENT OF CHEESE WHEY Disadvantages Lack of alkalinity High COD concentration The tendency to acidify very rapidly The difficulty to obtain granulation The tendency to produce an excess of various exopolymeric materials Reduces sludge settleability (A cause of biomass washout)

6 Reactor type Turkish German Symposium - Recent Advances in Wastewater Treatment Table 1. Data on anaerobic treatment of cheese whey HRT (days) Influent COD conc. (g/l) OLR (g COD/L.day) RE (%) Reference UFFLR Wildenauer and Winter, 1985 DSFFR De Haast et al., 1985 FBR Boening and Larsen, 1982 FBR Denac and Dunn, 1988 AAFEB Switzenbaum and Danskin,1982 SDFA Barford et al., 1986 UASB Schroder and De Haast, 1989 UASB Yan et al., 1989 DUHR Malaspina et al., 1995 AP Monroy et al., 1995 TSUAD Ghaly, UASB Kalyuzhnyi et al., 1997 UASB Kalyuzhnyi et al., 1997

7 Most of the studies on anaerobic treatment of cheese whey dealt with diluted (or deproteinated) whey. Anaerobic treatment of undiluted cheese whey stability problems (Kalyuzhnyi et al., 1997). Thus, requires long HRT values (5-20 days) This may reduce one of the major attractions of anaerobic systems in terms of lower HRT values and corresponding smaller reactor volumes and lower capital costs. Even though the superiority of two-stage anaerobic processes over conventional single-stage treatment was reported (Wiegant et al., 1986; Speece et al., 1997; Demirer and Speece, 1998; Demirer and Speece, 2000), a two-stage configuration was used for the anaerobic treatment of cheese whey only in one study up to date (Table 1).

8 OBJECTIVE * To determine the anaerobic treatability and methane generation potential of cheese whey in batch reactors, * To examine the nutrient and trace metal supplementation on the batch anaerobic treatment of cheese whey, * To determine high-rate anaerobic treatability of cheese whey in single- and two-stage UASB reactors.

9 1. Characterization of cheese whey Turkish German Symposium - Recent Advances in Wastewater Treatment Cheese whey from a cheese production factory located near the city of Samsun. Table 2. Characterization of the cheese whey used in biochemical methane production (BMP) and upflow anaerobic sludge blanket (UASB) reactor experiments Parameter Cheese whey (in BMP) Cheese whey (in UASB) ph Chemical Oxygen Demand (COD) mg/l mg/l Total Phosphorus (TP) mg/l Total Khjeldahl Nitrogen (TKN) mg/l Suspended Solids (SS) mg/l Volatile Suspended Solids (VSS) mg/l

10 2. BMP Experiments Turkish German Symposium - Recent Advances in Wastewater Treatment * to determine anaerobic biodegradability and biogas production of cheese whey studied. * to compare the supplementation of nutrient and trace metals on gas production. Procedure: - Addition of... * mixed anaerobic cultures (from Ankara WWTP - Anaerobic Sludge Digesters) * basal medium (only to the one of the two sets) * cheese whey...into the serum bottles (of 125 ml, with 50 ml liquid volume). - Purging the bottles with a gas mixture of CO 2 :N 2 (25:75) for 3-4 min. - Incubating the bottles in a temperature controlled room at 35±2 0 C. - Measuring the daily produced gas by a water displacement device.

11 Table 3. Experimental set-up of BMP experiments Reactor No Basal Medium Supplementation COD (mg/l) * run as duplicates * * BASAL MEDIUM CONTENT: NH 4 Cl (1200), MgSO 4.7H 2 O (400), KCl (400), Na 2 S.9H 2 O (300), CaCl 2.2H 2 O (50), (NH 4 ) 2 HPO 4 (80), FeCl 2.4H 2 0 (40), CoCl 2.6H 2 0 (10), KI (10), MnCl 2.4H 2 0 (0.5), CuCl 2.2H 2 0 (0.5), ZnCl 2 (0.5), AlCl 3.6H 2 0 (0.5), NaMoO 4.2H 2 O (0.5), H 3 BO 3 (0.5), NiCl 2.6H 2 0 (0.5), NaWO 4.2H 2 O (0.5), Na 2 SeO 3 (0.5), cysteine (10), NaHCO 3 (6000) (Demirer and Speece, 1998). (concentrations are given in parenthesis as mg/l)

12 Cumulative Gas Production (ml) Control with no BM 5525 mg/l COD with no BM mg/l COD with no BM mg/l COD with no BM Control with BM 5525 mg/l COD with BM mg/l COD with BM mg/l COD with BM Figure 1. The gas production values of the serum bottles used in the BMP experiments Time (days)

13 Gas Production (ml) Minimum Theoretical Average Theoretical Maximum Theoretical Experimental with BM Experimental with no BM COD Concentration (mg/l) Figure 2. Comparison of the theoretical and experimental gas production for BMP experiments

14 3. UASB Experiments * to determine high-rate anaerobic treatability of cheese whey in singleand two-stage UASB reactors. * to investigate, significance of process staging, operational parameters such as HRT, influent COD concentration and loading rate. Feed Solution: cheese whey diluted by the ratio of 4/5 with the five times concentrated Basal Medium. (average COD: mg/l) Granular cultures: from UASB reactor of Tekel Pasabahce Liquor Factory in located Istanbul. Mixed liquor suspended solids (MLSS) : ±19974 mg/l Mixed liquor volatile suspended solids (MLVSS) : ±19715 mg/l

15 Table 4. The dimensions, effective volumes, flowrates, hydraulic retention times (HRTs) and the biomass inventories of the UASB reactors used Operation Diameter and the Height of the UASB (cm) Effective Volume of the UASB (L) HRT (days) Biomass Inventory in the System (grams) First-stage (5.2x100) Second-stage (5.2x100) Analytical Measurements: * ph * COD analysis * Volatile fatty acids (VFA) * Bicarbonate alkalinity

16 COD Loading Rate (mg/l.day) COD (mg/l) HRT (days) ph Bicarbonate Alkalinity (mg/l) VFA (mg/l) Figure 3. Anaerobic bioconversion of cheese whey in the first-stage UASB reactor (a) HRT of the system, (b) COD loading rate, (c) Influent and effluent COD conc., (d) Influent and effluent ph, (e) Influent and effluent bicarbonate alkalinity, (f) Effluent VFA conc. a b c d e f Influent Effluent Influent Effluent Influent Effluent Time (days)

17 Table 5. HRT, influent and effluent COD concentrations and loading rate applied and the average COD removal efficiency observed in the first-stage UASB reactor Days HRT (days) COD Concentration (mg/l) Influent Effluent COD Loading Rate (g/l.day) Average COD Removal Efficiency (%)

18 HRT (days) COD Loading Rate (mg/l.day) COD (mg/l) ph Bicarbonate Alkalinity (mg/l) VFA (mg/l) Influent 2000 Effluent d Influent 7 Effluent Influent 4000 Effluent f Time (days) Figure 4. Anaerobic bioconversion of cheese whey in the second-stage UASB reactor (a) HRT of the system, (b) COD loading rate, (c) Influent and effluent COD conc., (d) Influent and effluent ph, (e) Influent and effluent bicarbonate alkalinity, (f) Effluent VFA conc. a b c e

19 Table 6. HRT, influent and effluent COD concentrations and loading rate applied and the average COD removal efficiency observed in the second-stage UASB reactor Days HRT (days) COD Concentration (mg/l) COD Influent Effluent Loading Rate (g/l.day) Average COD Removal Efficiency (%)

20 CONCLUSION * High rate anaerobic treatment of undiluted cheese whey in UASB reactors is a very efficient and cost-effective method. * Nutrient, trace metal and/or alkalinity supplementation is vital for the anaerobic treatment of cheese whey. * Anaerobic bioconversion of cheese whey yielded biogas, which has a high methane content (77 5 %). * The anaerobic methane generation from the cheese whey studied was found to be 424 ml CH 4 /g COD or 23.4 L CH 4 /L cheese whey.

21 Cont`d * Unlike most of the studies in the literature on the subject (Table 1), undiluted cheese whey could be treated anaerobically at relatively short HRT values ( days) without any significant stability problems. * HRT values as low as 2-3 days can be used for the anaerobic treatment of cheese whey, with a COD removal efficiency of % at influent COD concentration of mg/l. * A second-stage UASB achieved only slight additional COD removal efficiency of %. However, this efficiency could possibly be increased if longer HRT values were used and/or effluent recycle was applied.

Nutrient Removal at Wastewater Treatment Facilities. Nitrogen and Phosphorus. Gary M. Grey HydroQual, Inc. ggrey@hydroqual.com 201 529 5151 X 7167

Nutrient Removal at Wastewater Treatment Facilities Nitrogen and Phosphorus Gary M. Grey HydroQual, Inc. ggrey@hydroqual.com 201 529 5151 X 7167 1 Agenda Nitrification and Denitrification Fundamentals