Project Details

n Project Name: Landfill Leachate Treatment Project at Shenzhen Energy Environmental Protection East Co., Ltd. Wastewater Station
n Project Location: No. 1 Huanbao Road, Pingdi Street, Longgang District, Shenzhen
n Project Description:
Shenzhen Energy Environmental Protection East Co., Ltd. is located in Shangkengtang, Sifangpu Community, Pingdi Street, Longgang District, Shenzhen. The facility is equipped with a leachate treatment system designed for a daily capacity of 1,450 m³/d.The core process of the leachate treatment system includes: Pretreatment + Anaerobic Treatment + External MBR + Nanofiltration (NF) + Reverse Osmosis (RO). The system is configured with dual parallel lines operating independently starting from the anaerobic tanks.The membrane advanced treatment system comprises:4 sets of ultrafiltration (UF) membrane integrated units (8 groups total),1 set of nanofiltration (NF) membrane integrated units (2 groups total),1 set of reverse osmosis (RO) membrane integrated units (2 groups total),1 set of nanofiltration concentrate reduction membrane integrated units (2 groups total).By-products such as RO concentrate and primary membrane concentrate generated from NF concentrate reduction are returned to the power plant for further treatment.The treated leachate meets the water quality standards for make-up water in open recirculating cooling water systems specified in GB/T 19923-2005 (Reuse of Urban Recycling Water—Water Quality Standards for Industrial Uses).
n Leachate Source and Characteristics:
The leachate treated in this project primarily originates from fresh leachate generated during waste transfer and storage collected by the incineration plant. Landfill leachate exhibits characteristics such as diverse pollutant types, complex composition, and significant fluctuations in water quality and quantity. It contains high concentrations of pollutants including chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen, along with various heavy metals and microorganisms, posing severe environmental hazards if discharged untreated.

Treatment Process

a. Two-stage AO biochemical treatment: A two-stage AO process with pre-denitrification and post-nitrification is adopted. In the denitrification tank, carbon sources in the influent are utilized to reduce nitrate nitrogen and nitrite nitrogen into nitrogen gas. In the nitrification tank, ammonia nitrogen is oxidized to nitrate nitrogen and nitrite nitrogen. The secondary nitrification-denitrification further ensures complete nitrogen removal and compliance with total nitrogen standards in the effluent. This process fully utilizes carbon sources in the influent, reduces the oxygen demand for degrading organic pollutants in the nitrification tank, and improves treatment efficiency.
b. Built-in MBR System: After wastewater enters the membrane reactor, the majority of pollutants are degraded. The built-in MBR membranes utilize the upward shear force generated by gas-liquid interaction during aeration to achieve a cross-flow effect on the membrane surface, thereby reducing membrane fouling. Compared to external ultrafiltration membranes, the built-in ultrafiltration membranes operate with lower energy consumption, reducing operational costs. Ultrafiltration effectively removes suspended solids, colloids, macromolecular organic matter, and other impurities from the wastewater, ensuring stable operation of subsequent nanofiltration systems.
c. Nanofiltration Deep Treatment: The nanofiltration treatment process is adopted, with the nanofiltration system achieving a clear water yield of 85%. The concentrate enters the concentrate treatment system, and the treated effluent is returned to the regulation tank, while the clear water proceeds to the RO system for further removal of residual pollutants. Nanofiltration effectively removes small-molecule organic matter, divalent and multivalent ions, and other impurities from the leachate, further enhancing the effluent quality.
d. Nanofiltration Concentrate Treatment: The nanofiltration concentrate in this project is treated using a two-stage material separation membrane process. After treatment with the two-stage material separation membranes, the COD and color of the concentrate are significantly reduced, while the BOD5/COD ratio increases, enhancing the biodegradability of the concentrate. The effluent, after further filtration through the RO system, can essentially meet the reuse water standards for the power plant.
e. Reverse Osmosis Deep Treatment: The RO treatment process is adopted, with the RO system achieving a clear water yield of 75%. The concentrate enters the concentrate collection tank and is returned to the power plant for further treatment, while the clear water flows into the reuse water tank to serve as make-up water for the power plant's circulating cooling system.

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