Improving Water Resources Management through Water Reclamation and Reuse Lluís Sala [email protected] Workshop “Water Reclamation and Reuse in the 21st Century: Challenges and Opportunities” Riyadh, 29-30 June 2009 What is reclaimed water? (Definitions for water richer environments) • Urban wastewater: liquid waste produced by human activity that is transported through sewer lines and that needs to be adequately treated before discharge into the environment. • Wastewater treatment (= secondary treatment): usually biological treatment applied to wastewater to be delivered back to the environment without an adverse impact. Reference parameters: BOD, SS (and N and P, in sensitive waters) • Reclamation treatment (= tertiary treatment): any treatment beyond secondary that produces water that can be safely reused for a certain purpose: – Health protection criteria – potential contact between humans and reclaimed water. Disinfection is the key process. – Environmental criteria – reclaimed water will be used for nature enhancement and contact with humans is not likely to happen. Treatment designed mainly for eutrophication control. • Water reuse: second use of a properly reclaimed water. • Water reclamation and reuse goes well beyond an improved wastewater treatment Fantasy, fashion or necessity? • Is water reuse a fantasy? – No! Increase in water reuse projects implemented worldwide, specially in dry areas • Is water reuse a fashion? – No! Projects on operation get improved, not abandoned. • Is water reuse a necessity? – Gabriel Borràs (Head of the Planning Dept., Catalan Water Agency, NE Spain): “Water reuse has an essential role in our water resource management. Used water, when treated, is not a waste product but an essential water resource ” – Ramon Folch (Chair of Polytechnic University of Catalonia's Social Council and Professor of the UNESCO Chair for Sustainable Development): “If wastewater treatment plants would turn into reclamation plants we would have reclaimed water, pure and clear. We should think about it. After all, the bottled water we drink is reclaimed water too. By the natural cycle, but reclaimed. If we already do desalination, why don’t we do reclamation, which is easier ”? (Excerpt from the article “Aigua llençada” (“Wasted water”), on El Periódico de Catalunya, 8th July 2007). Change of paradigm • “Treat and dispose” is obsolete, specially in water scarce areas • Develop new resources with the least environmental impact: – Increasing limitation in water transfers (as a general rule) – Desalination plants – energy consumption & CO 2 emissions (Kyoto protocol) – Water recycling: give water a second chance • All the water used for urban supply is concentrated in one facility (useful volumes) • Most treatment before reuse is already provided by biological secondary treatment – “To get the water out the waste” • Usually useful at municipal or supramunicipal level (small to medium WWTP); only large WWTP can generate volumes with impact on the regional balance Why reclaimed water? (I) • Today’s technology allows the production of safe water from virtually any source • A great portion of the overall water demand is for non-potable uses ⇒ Okun (1998): “only about 15% of water used in urban areas (of US) is required to be of potable quality” • It is a local resource: water is already in the vicinity of where it has to be used – possibility of decentralized supply • It is an auxiliary resource: it can save precious drinking water or water with environmental functions Why reclaimed water? (II) • Where traditional resources have been fully used, reclaimed water may be the new resource with the least marginal cost • Safe water can be produced at reasonable costs, specially if desalination is not needed • Under certain circumstances, simultaneous energy savings can be achieved (lower CO 2 emissions, climate change) ENERGY CONSUMPTION OF WATER SOURCES IN TOSSA DE MAR, COSTA BRAVA 6,00 5,00 4,00 3,00 2,00 Consumption, kwh/m3 Consumption, 1,00 0,00 Groundwater (Tordera Groundwater (local Desalination (in Reclaimed water wells in Blanes) wells) Blanes) (Title-22) Kind of water Withdrawal Treatment Transportation The role of reclamation • After urban use, water quality can be restored to a great extent, so it can be beneficially reused again instead of discharged • Reclamation is a water resource generation activity, not only an extension of the wastewater treatment • Similar function –but different scale- than a reservoir, an aquifer or a desalination plant ⇒ to produce water, despite that the purpose is not for drinking water supply • Reclamation makes wastewater treatment plants work better The reclamation treatment • The better the quality of secondary effluent, the easier the reclamation process and the safer and consistent the activity will be - need to push performance beyond discharge limits • Disinfection is the essential process – It is aimed at reducing at safe levels the microbiological risk: – Wide range disinfection: UV + Cl 2 – Inactivation capacity similar than concentration of indicators (= greater than the concentration of pathogens) • Preparation processes, ahead of disinfection may be needed (coagulation, flocculation, sedimentation, filtration) • Combination of disinfectants reduces chlorine doses = lower risk of THM formation. Proven results with ozone, UV, UV + chlorine. Greater removal of microorganisms and more diversity targeted (bacteria, viruses, Cryptosporidium . • On-line probes for the measurement of turbidity and residual chlorine or redox potential – great reliability to the supply ⇒ Water not fulfilling quality requirements shall not leave the facility Reclaimed water quality • Influenced both by kind of biological and reclamation treatments Kind of facility Reclamation plant (between brackets, year of construction) Empuriabrava Pals (c) Castell-Platja d’Aro Blanes Wastewater treatment Extended aeration Extended aeration Conventional activated Extended aeration (1995) (1995) sludge (1983) (1998) Reclamation treatment Constructed wetlands Chlorination Filtration, disinfection “Title-22” (d) (1998) (2000) (1998) (2002) Volume treated in 2008, m 3 1,027,000 440,000 786,000 2,127,000 Statistical parameters (a) Average P90 Average P90 Average P90 Average P90 Suspended solids, mg/L 8.5 18,9 3.5 5.0 5.4 7.8 1.7 2.4 Turbidity, NTU 2.5 3.6 1.3 1.9 2.7 4.2 1.7 2.2 Escherichia coli , cfu/100 mL 35 180 < 1 < 1 2 19 3 6 Total nitrogen, mg N/L (b) 1.5 2.4 5.9 11.4 35.9 52.0 10.4 13.2 Total phosphorus, mg P/L 5.0 6.9 4.3 6.0 4.1 5.7 1.3 1.8 (a) Annual arithmetic averages for all parameters, except for the Escherichia coli concentrations, which are geometric averages. P90 is the percentile 90 of the annual set of data. (b) In the Empuriabrava case, organic nitrogen (ammonia + nitrite + nitrate) (c) Water at the inlet of the storage pond at Golf Serres de Pals (d) The “Title-22” treatment is composed by coagulation, floculation, sedimentation, filtration and disinfection. In the case of Blanes, phosphorus is removed by chemical precipitation. Reclaimed water quality • Influenced both by kind of biological and reclamation treatments Kind of facility Reclamation plant (between brackets, year of construction) Empuriabrava Pals (c) Castell-Platja d’Aro Blanes Wastewater treatment Extended aeration Extended aeration Conventional activated Extended aeration (1995) (1995) sludge (1983) (1998) Reclamation treatment Constructed wetlands Chlorination Filtration, disinfection “Title-22” (d) (1998) (2000) (1998) (2002) Volume treated in 2008, m 3 1,027,000 440,000 786,000 2,127,000 Statistical parameters (a) Average P90 Average P90 Average P90 Average P90 Suspended solids, mg/L 8.5 18,9 3.5 5.0 5.4 7.8 1.7 2.4 Turbidity, NTU 2.5 3.6 1.3 1.9 2.7 4.2 1.7 2.2 Escherichia coli , cfu/100 mL 35 180 < 1 < 1 2 19 3 6 Total nitrogen, mg N/L (b) 1.5 2.4 5.9 11.4 35.9 52.0 10.4 13.2 Total phosphorus, mg P/L 5.0 6.9 4.3 6.0 4.1 5.7 1.3 1.8 (a) Annual arithmetic averages for all parameters, except for the Escherichia coli concentrations, which are geometric averages. P90 is the percentile 90 of the annual set of data. (b) In the Empuriabrava case, organic nitrogen (ammonia + nitrite + nitrate) (c) Water at the inlet of the storage pond at Golf Serres de Pals (d) The “Title-22” treatment is composed by coagulation, floculation, sedimentation, filtration and disinfection. In the case of Blanes, phosphorus is removed by chemical precipitation. Reclaimed water quality • Influenced both by kind of biological and reclamation treatments Kind of facility Reclamation plant (between brackets, year of construction) Empuriabrava Pals (c) Castell-Platja d’Aro Blanes Wastewater treatment Extended aeration Extended aeration Conventional activated Extended aeration (1995) (1995) sludge (1983) (1998) Reclamation treatment Constructed wetlands Chlorination Filtration, disinfection “Title-22” (d) (1998) (2000) (1998) (2002) Volume treated in 2008, m 3 1,027,000 440,000 786,000 2,127,000 Statistical parameters (a) Average P90 Average P90 Average P90 Average P90 Suspended solids, mg/L 8.5 18,9 3.5 5.0 5.4 7.8 1.7 2.4 Turbidity, NTU 2.5 3.6 1.3 1.9 2.7 4.2 1.7 2.2 Escherichia coli , cfu/100 mL 35 180 < 1 < 1 2 19 3 6 Total nitrogen, mg N/L (b) 1.5 2.4 5.9 11.4 35.9 52.0 10.4 13.2 Total phosphorus, mg P/L 5.0 6.9 4.3 6.0 4.1 5.7 1.3 1.8 (a) Annual arithmetic averages for all parameters, except for the Escherichia coli concentrations, which are geometric averages. P90 is the percentile 90 of the annual set of data. (b) In the Empuriabrava case, organic nitrogen (ammonia + nitrite + nitrate) (c) Water at the inlet of the storage pond at Golf Serres de Pals (d) The “Title-22” treatment is composed by coagulation, floculation, sedimentation, filtration and disinfection.