Full scale ozonation of WWTP effluent followed by sandfiltration

Transcription

1 Schweizerische Eidgenossenschaft Confédération suisse Confederazione Svizzera Confederaziun svizra Full scale ozonation of WWTP followed by sandfiltration Saskia Zimmermann, S. Brocker, B. Escher, P.A. Hansen, J. Hollender, S. Koepke, M. Krauss, H.F. Larsen, A. Magdeburg, C.S. McArdell, J. ehlmann, C. rt, D. Rensch, H. Siegrist, H. Singer, D. Stalter, M. Suter, U. von Gunten Eawag: Swiss Federal Institute of Aquatic Science and Technology Full scale ozonation at WWTP Regensdorf Primary activated sludge treatment sedimentation Secondary 3 3 m 3 Primary sedimentation zonation Downstream WWTP Sand Sand filtration filtration sampling points m 3 wastewater per day under dry weather conditions (. population equivalents) Upstream WWTP

2 zonation FS 7.7m 3.3m 3 3.m 3 sand filter.3m 3 8.m 3.3m 3.m 3 3. m 8 9.m 3 V tot =3.m 3.7 m. m. m. m. m. m width. m. m zone dosing DC-load proportional flow proportional Sampling sampling campaigns (. g 3 /g DC ) h- or 8h-volume proportional composite samples Fitration on-site (.7 μm glassfiber filters) Elimination efficiency micropollutants sampling campaigns:. ±. g 3 /g DC Concentration (ng /L) H 3C H CH 3 H H 3C CH 3 H CH 3 H - CH 3 H Clarithromycin Carbamazepine Diclofenac Mefenamic acid aproxen Sulfamethoxazole Atenolol Benzotriazol Mecoprop Methylbenzotriazol IopromideS H Primary Secondary < LQ < LQ < LQ < LQ zonation Sand filtration Creek upstream WWTP Creek downstream WWTP

3 Elimination efficiency micropollutants sampling campaigns:. ±. g 3 /g DC umber Secondary Effluent > ng/l zonation > ng/l zonation > ng/l Pharmaceuticals 3 Atenolol Antibiotics X-Ray contrast media Diatrizoate, Iopromide Biocides/Pesticides 3 Mecoprop Corrosion inhibitor (Methyl)-Benzotriazol Endocrine disruptors Metabolites Total Load reduction per year: ~ kg Carbamazepine ~ kg Diclofenac ~ kg Benzotriazole Effect of ozone concentration on elimination efficiency Calculation: *c after ozonation / c secondary Diclofenac Trimethoprim g 3 /g DC Sulfapyridine. Carbamazepine.79 ±.. ±. Clarithromycin. ±. Sulfamethoxazole Metoprolol Methylbenzotriazol Bezafibrate Benzotriazol Atenolol Mecoprop Atrazine Iopromide 8 Elimination (%) 3

4 Cancerogenic nitrosamines - byproducts of ozonation? Mean values of 9 - sampling campaigns Concentration (ng/l) 3 DBA DEA DMA MR PIP Primary Secondary zonation Sand filtration xidation by-products Bromate influent bromide levels ~3 μg/l 7. ug/l for the highest ozone dose of. g 3 /g DC bromate < drinking water standard ( μg/l) bromate < proposed ecotoxicological threshold (3 mg/l) H H, H CH 3 H H Assimilable rganic Carbon (AC) influent AC levels μg/l increases up to 7 μg/l SF decreases it by max. %

5 Disinfection [cells/ml].... Final sedimentation Total cell counts Total cell counts zonation E. coli E. coli Sand filtration g 3 /g DC E.coli/ml. Final sedimentation zonation Sand filtration on specific toxicity Toxic effects: mode-of-action based battery Extraction of organic micropollutants and effect assessment of extracts Mode of action Bioassay Targeted chemicals baseline toxicity Bioluminiscence inhibition assay all chemicals Specific toxicity Receptor + C H + 3 Phytotoxicity photosynthesis inhibition estrogenic effects acetylcholinesterase (AChE) inhibition Imaging-PAM YES AChE Triazine and phenylurea herbicides Estrogens, estrogenic Industrial chemicals rganophosphates, carbamate insecticides Reactive toxicity genotoxicity umuc Chlorinated byproducts, Aromatic amines, PAH

6 Elimination efficiency toxic effects Bioluminescence inhibition test Combined Algae Test (Photosynthesis) Combined Algae-Test (growth) YES assay Acetylcholinesterase Inhibition test 8 78 DEQ (µg/l) PTEQ (µg/l) EEQ (ng/l) g 3 /g DC..79 ±.. ±.. ±. Elimination by ozonation plus sandfiltration [%] at. g 3 /g DC - 9 % elimination of the toxic effect Specific, receptor-mediated effects better removed than non-specific toxicity (ozone causes transformation not mineralisation) no significant formation of toxic or genotoxic byproducts Fish early life stage toxicity test Swim-up and biomass comparison (ncorhynchus mykiss larvae) Swim-up [% SEM] 7 Regensdorf C FS SF Z biomass [% SEM] Regensdorf : p<. Days - Z : p<. SF Delayed swim-up after Z Reduced biomass after Z o significant effect after sand filtration

7 Lumbriculus toxicity test Biomass comparison biomass/replicate [% SEM] Regensdorf :p<. Z SF Considerable decrease of biomass and reproduction after Z o significant effect after sand filtration 3 Energy consumption for and 3 Energy consumption (m 3 process gas h - ) Energy consumption [kwh kg - 3] 3 3 Total: 3 process + production + transport 3 process: Container + online probes + computers Container: 3 production + thermal ozone distructor + cooling aggregate 3 production: dielectric barrier discharge, control system Process gas concentration [g 3 m -3 process gas] 7

8 Estimated yearly costs ozonation step at WWTP Regensdorf Unit Investment (a / %) a Personnel b Maintenance xygen c Energy d Total Spec. Costs (for 3 Mio. m 3 wastewater / a) /a /a /a /a /a /a /m 3 wastewater a payback period years, linear amortization with % interest b based on 7 h/year internal personnel plus external personnel for maintenance of DC sensor, ozone dissolved measurement and gas warn devices c based on. /kg d based on energy costs of.8 /kwh without sand filtration Secondary - directly emitted ( micropollutants) Global warming Acidification utrient enrichment LCA impact profiles (weighting factor = for all impact categories) Photochemical oxidation Human toxicity soil Human toxicity water Ecotoxicity soil Ecotoxicity water Total 8 8 µpet/m 3 After ozonation;,8g ozon/m3 ( micropollutants) Global warming Acidification utrient enrichment Photochemical oxidation Human toxicity soil Human toxicity water Ecotoxicity soil Ecotoxicity water Total Avoided:, µpet/m3 Induced: 8,9 µpet/m3 8 µpet/m 3 8

9 Environmental sustainability profiles: ozonation ( micropollutants (only significant ones shown); weighting factor = for all impact categories) µpet (WF=) Induced Avoided DMA Clofibric acid Propanolol Metoprolol Atenolol Carbamazepin Ibuprofen Diclofenac Bezafibrate Sulfamethoxazole Roxithromycin Erythromycin Clarithromycin Energy Ancilliary Infrastructure.8g 3 zonation Environmental sustainability profiles: ozonation + sand filtration (3 micropollutants + P (only significant ones shown); weighting factor = for all impact categories) Secondary After sandfiltration Removal rate Tot-P (mg/l),8,3, µpet (WF=) 8 8 Induced Avoided Tot-P Heavy metals DMA Clofibric acid Propanolol Metoprolol Atenolol Carbamazepin Ibuprofen Diclofenac Bezafibrate Sulfamethoxazole Roxithromycin Erythromycin Clarithromycin Energy Ancilliary Infrastructure.8g 3 zonation+sand filtration 9

10 Conclusions Efficient technique for the transformation of micropollutants and for disinfection purposes Ecotoxicity results are controversial (improvement vs. no effect); ongoing need for clarification Sand filtration recommended as barrier for the elimination of some oxidation by-products formed during ozonation (DMA, AC) Specific costs ~. /m 3 wastewater (ozonation without sand filtration; including both investment and operation costs) LCA: zonation most probably environmentally sustainable; including sand filtration significantly improves sustainability profile Acknowledgments This study was part of the EU eptune project (Contract o 38, SUSTDEV--3.II.3.), which was financially supported by grants obtained from the EU Commission within the Energy, Global Change and Ecosystems Program of the Sixth Framework (FP--Global-) BAFU Switzerland AWEL Kanton Zürich

11 Schweizerische Eidgenossenschaft Confédération suisse Confederazione Svizzera Confederaziun svizra Thank you for your attention! Eawag: Swiss Federal Institute of Aquatic Science and Technology