Transboundary water issues in a macro-regional context: the Danube basin 11-12 September 2013. Budapest Integrated solutions for waste water treatment in small settlements and rural areas Adrienne Clement, PhD clement@vkkt.me.hu Budapest University of Technology and Economics Department of Sanitary and Environmental Engineering
Background and objectives Action 5: To establish buffer strips along the rivers to retain nutrients and to promote alternative collection and treatment of waste in small rural settlements. Milestone n 5: Promoting best practices in WWT and Programme of Measures for solid waste management and wastewater treatment for small settlements. Work 2: Proposal for a supplementary, eco-friendly and site-specific waste water treatment units for less than 2000 PE small settlements where UWWTPs are financially non-feasible. Output 2: Scenario(s) for local and site-specific solutions of waste water treatment for less than 2000 PE settlements within the Danube region.
Why and whose is it important? Settlement structure in Hungary: Settlements < 2000 PE 1.7 Million people (17% of population) 2360 settlemets (75% of total) Impact on the environment (load) 10 Million people 14.5 Million Pe Treated: 11.5 M Pe Not treated: 3 M Pe Settlement category Total population Number of settlements < 500 277656 1042 500-1000 485142 674 1000-2000 929020 646 2000-5000 1498937 500 5000-10 000 922195 133 10 000-100 000 3067472 134 >100 000 2850431 9 Total 10030853 3138 68% of them are not sewered 14,5 M Pe Settlements > 2000 < 2000 10,8 1,9 0,7 1,1
Share of point and diffuse emissions on catchment level Quantification of point and non-point nutrient loads (PhosFate model) Point (wastewater) Non-point
Why sewerage systems are not be economically used? Specific pipe length (Km/house) 0,3 0,25 0,2 0,15 0,1 0,05 0 Number of settlements 1200 1000 1042 0 20 40 60 80 100 Population density (person/ha) 674 646 In small settlements low population density increases the network length resulting high investment costs. 800 600 400 200 0 Population density (person/ha) 100 80 60 40 20 0 500 person / ha 45 Population density 40 35 30 25 20 15 133 134 10 9 5 0 < 500 500-1000 1000-2000 2000-5000 5000-10 00010 000-100 000 >100 000 10 100 1000 10000 1000001000000 Settlement popolation (person)
TRADITIONAL SOLUTIONS FOR WASTE WATER TREATMENT AND DISPOSAL CENTRALISED (SEWER SYSTEM + WWTP) CONNECTION TO REGIONAL WASTEWATER TREATMENT PLANT (biological and tertiary) NATURAL TREATMENT (constructed wetlands, artificial wetlands, biofilters, ponds) DECENTRALISED (ON SITE) STORAGE AND DELIVERY TO WWTP SEPTIC TANK + DRAINFIELD SMALL SCALE PLANTS (AS-SBR, fixedfilm bio reactors) Environmental impact (receiving water body) Surface water Soil and groundwater
Impacts on surface water quality (1) Local effect: Increasing concentration of pollutants (nutrients, salt, metals) Oxygen depletion B DC = f (Q/q) C h2 C 0A A DC C h2 C 0B C HÉ Dilution x, t DO sag: Streeter & Phelps (1925)
Municipal wastewater treatment plants (2015) Ecological status versus dilution capacity of rivers downstream to wastewater discharges Dilution (Q/q) Dilution rate 10000 1000 100 10 Impacts on the water quality of receiving surface water Capacity (PE) Significant impact > 100 000 64% 10 000-100 000 48% 2 000-10 000 47% < 2000 19% Total 38% Significant means if the discharge in itself might deteriorate the receiving water body to fail ambient water quality criteria. Weak/Bad Moderate Good High Macroinvertebrates Phytobenton Physico-chemical quality
Impacts on surface water quality (2) Eutrophication on large catchment scale Lakes Large rivers, see bays Danube Basin and Black Sea 600 nitrogen (kt/a) 500 400 GERMANY AUSTRIA CZECH_RE SLOVAKIA HUNGARY SLOVENIA CROATIA YUGOSLAV BOSNIA_H BULGARIA ROMANIA MOLDOVA UKRAINE 27(5.0%) 8(1.4%) 15(21.3%) 21(4.0%) 34(6.4%) 300 69(12.8%) 200 100 Danube longitudinal instream-load profile 22(4.1%) 19(3.6%) 30(5.6%) 30(5.5%) 15(2.8%) 77(14.4%) 70 (13%)
Exceeding the threshold value (C > 50 mg/l) >50 mg/l nitrát tartalmú pontok gyakorisága Impacts on groundwater quality Frequency A nitrát határérték of exceeding túllépések (>50 the mg/l) threshold gyakorisága a value VKI monitoring (C > pontjain 50 mg/l) 35% 30% 25% 20% 15% 10% 5% 0% 0-5 5-10 10-20 20-30 szűrőzés mélysége [m-m] Depth of the well (m) 30-50 50-100 >100 települési Urban Agricultural mezőgazdasági erdő Forest
Technical solutions for on site treatment (1)
Technical solutions for on site treatment (2) Source: Boda-Patziger, 2010
Natural treatment F&N Umweltconsult GmbH Source: Boda-Patziger, 2010
Effluent water quality (10 < PE < 20) NH4-N COD NO3-N Source: Boda-Patziger, 2010
MULTI-CRITERIA EVALUATION Connection to regional WWTP Sewerage and local natural treatment Septic tank and drainfield On site (small scale) treatment Operation and maintenance Costs (investment and operation) Legislation, compliance with effluent limits?
Innovative solutions Wastewater treatment by source separation Closing nutrient cycle, on-site disposal and reuse rainwater irrigation storage drinking water toilet kitchen bath yellow-water greywater braunwater
SELECTION PARAMETERS TO SUPPORT DECISION MAKING (1): COSTS Beruházási Specific investment költség (Ft/telek) cost (EUR/person) 3500000 7000 decentralizált On-site: septic (oldómedence+szikkasztás) tank + drainfield 3000000 6000 Vacuum sewerage for black water, gray water infiltration fekete: On-site komposzt separation: WC, dry s.szürke: toilet, gray szikkasztás water infiltration 2500000 csatorna+központi Sewerage + centralised szennyvíztisztító WWTP 4000 2000000 3000 1500000 2000 1000000 1000 500000 0 0 fekete: vákuumos csat., anaerob tiszt., szürke: helyi, szikkasztás 10 100 1000 10000 100000 1000000 Település Number (agglomeráció) of inhabitants mérete (Pe) (LA, fő)
SELECTION PARAMETERS TO SUPPORT DECISION MAKING (2): ENVIRONMENTAL CRITERIA CRITERIA PHYSICAL (INFILTRATION IS NOT POSSIBLE) ENVIRONMENTAL WFD OBJECTIVES (GOOD STATUS) IMPERMEABLE COVER HIGH POPULATION DENSITY SHALLOW GROUNDWATER TABLE VOULNERABLE GROUNDWATER PROTECTED SURFACE WATER (DRINKING WATER AND RECREATIONAL USE
Groundwater voulnerable areas Open carstic area Drinking water resource Long-term water resource
Settlements on groundwater voulnerable areas Open carstic area Drinking water resource Long-term water resource
Average population density (person/ha) < 15 fő/ha 15-35 35-70 > 70
Átlagos Depth of laksűrűség groundwater településenként table < 2 m 2-4 m 4-6 m 6-8 m > 8 m
Soil not suitable for filtration (inpermeable layer > 3 m)
ON-SITE TREATMENT AND DISPOSAL IS APPLICABLE 1432 SETTLEMENTS
METHODOLOGY TO SELECT OPTIMAL SOLUTION: RESULTS (BUTE, 2006) Suggested alternative for each settlement Sewerage and transport to centralised WWTP Centralised combined with on-site disposal (septic tanks) Centralised combined with grey water separation Traditional on-site disposal (septic tanks, drainfield) Centralised: sewerage and WWTP On-site: septic tanks, drainfield or separated disposal (grey-black) Vacuum sewerage for black water, gray water infiltration Grey water filtration, black water collection and anaerob treatment Infrastructure is not required (100% of the population is supplied)
CONCLUSIONS FROM ENVIRONMENTAL AND PUBLIC HEALTH VIEW POINTS THERE ARE ACCEPTABLE TECHNICAL SOLUTIONS LOCAL SOLUTIONS COULD SAVE 40-60% OF COSTS NATURE OF APPLICATION RESTRICTIONS ARE NOT TECHNICAL RATHER: ECONOMIC (SUBSIDIES) INSTITUTIONAL (WHO WILL OPERATE?) REGULATORY AND SUPERVISION/REJECTION OF EXCLUSIVITY OF TRADITIONAL WAY OF THINKING Thank you for your attention!