When stepping into the Laohuchong Landfill, you would be overwhelmed by the strong smell from the leachate collection pool. In the past, the leachate from the landfill was collected into a huge pool for natural volatilization. However, the rate of volatilization was far less than that of leachate generation. Whenever the rainy season came, the landfill leachate in the collection pool was in danger of spilling out. At present, Laohuchong Landfill has gathered 520,000 m3 of leachate to be treated, facing a huge security and environmental threat. The Central Environmental Protection Supervision Team requires that all the leachate must be treated before the end of 2019.
After analyzing the water quality, the China Urban Construction Research Institute has selected the treatment process of “softening + two-passage Disc Tube Reverse Osmosis (DTRO) + High Pressure Reverse Osmosis (HPRO) + Ion Exchange.” We signed the first contract on April 3, 2018, and the first five sets of DT special membrane equipment with daily processing capacity of 2100 m³ manufactured by us were delivered to the project site on April 13th. The permeate water generated with high standard on May 1. At present, the project is operating effectively and has set a new record in the efficiency of the domestic landfill leachate treatment field.
1. Simple pretreatment
2. High recovery rate, low energy consumption
3. Low chemical operation cost
4. Longer membrane lifespan, and the membrane can be replaced separately
5. Reliable system, high water quality and stable separating property
6. Small floor space, flexible and compact modular unit, high mobility
In addition, to fully utilize the advantages of Jinzheng DTRO system and improve the effect of "softening + precipitation" system, the process of leachate treatment was optimized as follows:
1. “two-stage DTRO + HPRO"was integrated into "two-stage DTRO." The DTRO system of our company could integrate the HPRO system into two-stage DTRO systems. This optimization could greatly decrease wastewater recycling in the system (because HPRO water is required to return to the two-passage DTRO system), and significantly reduce the number of membrane modules and related pumps and other equipment. At the same time, this optimization could cut down the structures of the pool, greatly improving the stability and reliability of the system.
2. The high-density pool was applied with magnetic flocculation technology to improve the precipitation efficiency.
3. PCF filter was used instead of sand filter to reduce the floor space, which improved the filtering efficiency.
Having been treated by our company’s membrane system, the wastewater in the landfill could be used for watering flowers and fish-farming. The wastewater in the landfill leachate was transfomed in a way to reach the same purification standard as tap water. The recovery rate of its clear water was above 70%. About 2,150 tons of stinky water was treated every day, and 1,500 tons of clean water would flow out after treatment for urban greening, irrigation and so on. In addition, the resulting residue could be used as tree fertilizer, or could be further purified to the discharge standard.