Water. desalination + reuse

PROJECTS Treatment Process Anaerobic treatment unit consists of dosing equipment, an anaerobic reactor and a biogas system. Outflow from the equalization tank is pumped into the inflow tank of the upflow anaerobic sludge blanket (UASB) reactor and then is evenly distributed into the anaerobic reactor after adding alkali, microelement and nutritive salt to adjust pH and water quality. The anaerobic reactor uses anaerobic microorganisms to degrade the organic pollutants in the wastewater. There is a gas-liquid-solid separator inside the UASB reactor. After gas-liquid-solid separation, water flows into the distribution well of the first aerobic tank by gravity, sludge returns to the reactor to maintain sludge concentration inside the reactor, biogas is transformed into the biogas cabinet after gas-liquid separation and comprehensively utilized after pressurization. Nanchong Chemical Industrial Park sewage treatment plant virtual aerial view Biological treatment unit comprises an initial aerobic tank, a middle sedimentation tank, a second A/O tank and a final sedimentation tank. After anaerobic treatment unit, PTA and PET wastewaters flow into the distribution well of the first aerobic tank together with return sludge of the middle sedimentation tank. PBT wastewater flows into the distribution well of the first aerobic tank directly. Fully mixed water in the distribution well flows equally into the two lines of the aerobic tanks, which use jet aerators to create an aerobic environment to degrade most organic pollutants. The outlet from the first aerobic tank flows into the middle sedimentation tank for water-sludge separation. The outflow of the middle sedimentation tank, together with circulating cooling wastewater, domestic wastewater and return sludge of the final sedimentation tank, flows into the distribution well of the second A/O tank. Fully mixed water in the distribution well flows equally into the two lines of the second A/O tanks. After the treatment in second A/O tank, wastewater flows into the final sedimentation tank for water-sludge separation. Advanced treatment unit includes a coagulation settler, an ozone unit, a biological aerated filter (BAF) and a manganese sand filter. Polyaluminium chloride and polyacrylamide is added to the coagulation settler for coagulation | 24 | Desalination & Water Reuse | November-December 2013 reaction to remove suspended solids (SS). Water is pumped into the ozone contact tank, which using the oxidizability of ozone to break the molecular chain of large organic matter. After modification in the ozone unit, wastewater flows into the BAF to decrease COD. The outlet of BAF enters the manganese sand filter to further remove suspended solids, manganese and cobalt. Reuse water treatment unit comprises a UF system and an RO system. Effluent from the manganese sand filter flows into the raw water tank of the UF. Lifted by UF feed pump, water flows through a self-cleaning filter for safety to intercept residual particles and SS. Then the water flows into the UF equipment to remove bio-pollutants, particles, colloids, turbidity, bacteria etc, so that the water quality can meet the inflow quality of the RO system. The water recovery rate is 90%, with regular clean water backwash and dosing backwash to remove fouling on membrane surface. A pipeline mixer at the exit of RO feed pump mixes water with a reducing agent and an antiscalant agent. The reducing agent can avoid the oxidizing agent in the water hurting RO membranes, while the antiscalant agent can avoid salt in the water scaling on RO membrane surface. After adding reducing agent and antiscalant agent, water flows into the RO membrane through the RO high-pressure pump and safety filter. The water recovery rate of the RO system is 70%, clean water flows into reuse water tank, while brine flows into the brine treatment unit.

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