Study on the Recycling and Reuse of Water Resources for the arid and Water-deficient Area in Western china Key Project of the National Natural Science Foundation of China(NSFc) ( Grant No.50138020) Background In western China especially the Consequently many people in this region northwestern region, people have been for cannot be supplied with the minimum distribution in china long suffering from chronic water shortage. amount of water for drinking and sanitary This restricts the speed of development purposes, and water shortage be and affects peoples' living quality. There more and more serious with the increase of are mainly three reasons for this problem population as well as industrial (1) Dry climate and low rainfall resulting development. Continuous development of in an absolute deficiency of total water exploitable water resources or long distance quantity water transfer may be one measure to solve (2)Water quality pollution due to natural the water shortage problem but this needs and artificial reasons, resulting in a large-scale investment and often causes shortage of qualitatively available water new environmental problems. Under such resources circumstances, water recycling and reuse is (3) Shortage of financial sources for thought to be a practical way to meet the water resource development or appropriate needs of sustainable development in rater treatment western China Study Outputs of centralized and decentralized treatment technologlespplicable Dynamic analysis and modeling Development of ap Advanced treatment processes A series of experimental studies were wastewater treatment and reuse Enhanced primary treatment conducted for advanced wastewater systems treatment for water reclamation. Application of ultrafiltration (UF)for tertiary reatment of the secondary effluent Development of a dispersed-ozone floatation(DOF separator for simultaneous Development of Suspended matter takes a large portion of hybrid submerge SwalE pee> membrane bioreactor which combines both the contaminants in the raw domestic suspended growth-activated sludge and wastewater and enhanced primary System dynamic(SD)method was applied treatment was found to be applicable to attached growth-biofilm with MF membrane for the development of a mathemati for wastewater treatment and reuse achieve a substantial removal of coD model for the analysis of a water supply BoD etc system which incorporates reclaimed Pilot study of a decentralized water from centralized or decentralized Combination of enhanced primary wastewater treatment and reuse system wastewater treatment as a supplementary treatment with biodegradation water resource, taking into consideration of Fluidized Pellet Bed Bioreactor social. economic and environmental Modeling and optimization of treatment for wastewater reuse A pilot plant was implemented in a village at Within a total hydraulic retention time the entrance of Xi'an Xiang-yu Forest Park, HRT)of 33 minutes, the FPB bioreactor using a modified SBR and enhanced filtration achieved coD. BoD, ss and tP removals process. The treated water is used for onsite 一 of90.0%,93.6%,95.6%and94.1% About 40% removal of tn and 35% Risk assessment of water reuse removal of NH3-n were also achieved The risk of using treated wastewater A soft package(SimWin) was developed A newly developed biofilm supporter various purposes of wastewater for an optimized selection of unit treatment assessed mainly regarding the pathogenic technology and combination of physical microorganisms. PCR assay was applied for physiochemical, biological and chemical a fast and accurate identification of processes for the treatment of domestic wastewater to meet the requirement of water reuse for certain purposes according Economic and management aspects to raw wastewater quality, scale of With its surface well modified with pore everal models were developed for economic treatment and reuse, and other factors size suitable for microorganisms to grov assessment of water reuse. Life Circle This leads to a rational design of a the newly developed medium is used as Assessment was used as a tool for a reatment plant to achieve water biofilm supporter in a turbulent bed or comprehensive analysis of both centralized reclamation in China, especially in the dry moving bed bioreactor to achieve effective and decentralized wastewater treatment and and water deficient northwestern regions removal of nitrogen and phosphorus use
Study on the Recycling and Reuse of Water Resources for the Arid and Water-deficient Area in Western China Key Project of the National Natural Science Foundation of China (NSFC) (Grant No. 50138020) In western China especially the northwestern region, people have been for long suffering from chronic water shortage. This restricts the speed of development and affects peoples’ living quality. There are mainly three reasons for this problem: (1) Dry climate and low rainfall resulting in an absolute deficiency of total water quantity; (2) Water quality pollution due to natural and artificial reasons, resulting in a shortage of qualitatively available water resources; (3) Shortage of financial sources for water resource development or appropriate water treatment. Study Outputs Background Dynamic analysis and modeling of centralized and decentralized wastewater treatment and reuse systems System dynamic (SD) method was applied for the development of a mathematic model for the analysis of a water supply system which incorporates reclaimed water from centralized or decentralized wastewater treatment as a supplementary water resource, taking into consideration of social, economic and environmental factors. Consequently many people in this region cannot be supplied with the minimum amount of water for drinking and sanitary purposes, and water shortage becomes more and more serious with the increase of population as well as industrial development. Continuous development of exploitable water resources or long distance water transfer may be one measure to solve the water shortage problem but this needs large-scale investment and often causes new environmental problems. Under such circumstances, water recycling and reuse is thought to be a practical way to meet the needs of sustainable development in western China. Modeling and optimization of treatment for wastewater reuse A soft package (SimWin) was developed for an optimized selection of unit treatment technology and combination of physical, physiochemical, biological and chemical processes for the treatment of domestic wastewater to meet the requirement of water reuse for certain purposes according to raw wastewater quality, scale of treatment and reuse, and other factors. This leads to a rational design of a treatment plant to achieve water reclamation in China, especially in the dry and water deficient northwestern regions. Development of applicable treatment technologies Enhanced primary treatment Suspended matter takes a large portion of the contaminants in the raw domestic wastewater and enhanced primary treatment was found to be applicable to achieve a substantial removal of COD, BOD etc. Combination of enhanced primary treatment with biodegradation – Fluidized Pellet Bed Bioreactor Within a total hydraulic retention time (HRT) of 33 minutes, the FPB bioreactor achieved COD, BOD, SS and TP removals of 90.0%, 93.6%, 95.6% and 94.1%, respectively from raw domestic sewage. About 40% removal of TN and 35% removal of NH3 -N were also achieved. A newly developed biofilm supporter With its surface well modified with pore size suitable for microorganisms to grow, the newly developed medium is used as biofilm supporter in a turbulent bed or moving bed bioreactor to achieve effective removal of nitrogen and phosphorus. 0.45m Dissolved Suspended BOD COD TP TN SS ←40% 60%→ ← 35% 65%→ ←50% 50%→ ←80% 20%→ Classification ←70%30%→ ←60%40%→ ←55% 45%→ ←30%70%Organic → Inorganic Original surface Modified surface Biomass on the surface Advanced treatment processes A series of experimental studies were conducted for advanced wastewater treatment for water reclamation: • Application of ultrafiltration (UF) for tertiary treatment of the secondary effluent • Development of a dispersed-ozone floatation (DOF) separator for simultaneous tertiary treatment and disinfection • Development of a hybrid submerged membrane bioreactor which combines both suspended growth-activated sludge and attached growth-biofilm with MF membrane for wastewater treatment and reuse. Pilot study of a decentralized wastewater treatment and reuse system A pilot plant was implemented in a village at the entrance of Xi’an Xiang-yu Forest Park, using a modified SBR and enhanced filtration process. The treated water is used for onsite irrigation. Risk assessment of water reuse The risk of using treated wastewater for various purposes of wastewater reuse was assessed mainly regarding the pathogenic microorganisms. PCR assay was applied for a fast and accurate identification of microorganisms. Economic and management aspects Several models were developed for economic assessment of water reuse. Life Circle Assessment was used as a tool for a comprehensive analysis of both centralized and decentralized wastewater treatment and reuse systems. R ational size of reused w ater C hange of reused w ater price Wastew ater drainage volum e Expected volum e of reused w ater treatm ent + Wastew ater treatm ent volum e + Financial dem and of reuse project Investm ent of reused w ater distributive netw ork Pipe m aintaining cost Financial dem and of reused w ater running + - Increasing rate of reused w ater + Factors influencing consum ers’ acceptable degree - + R eused w ater volum e + Wastew ater drainage coefficient + + Expected increasing rate of reused w ater - R eused w ater treatm ent size + - + + + + Legend 1 – raw water tank 2 – raw water pump 3 – static mixer 4 – flow meter 5 – FPB column 6 – agitating blades 7 – sampling tube 8 – motor 9 – outlet 10 – recycling water tank 11 – air dissolving pump 12 – pressure tank 10 1 Raw wastewater 11 12 Effluent 9 8 Air 2 3 4 PAM 4 6 5 PAC 7 Recycle