Household waste harmless disposal center leachate treatment project case

29 May, 2024 2:49pm

Project name: Hengdong County Heqiao household waste harmless disposal center leachate treatment workshop upgrade project

Project Overview:
Hengdong County Heqiao household waste harmless disposal center is located in Hengdong County Mishui Town Heqiao village 12 group, the site before Hengdong County city old dump, began to pile garbage in 2006, using a simple landfill.
According to the operation situation in the past two years, the storage of leachate is large, and the actual treatment scale of leachate is lower than the designed treatment scale. The early treatment effect is poor, resulting in the ultrafiltration, nanofiltration, reverse osmosis unit inlet water quality does not meet the requirements, the membrane system long-term ultra-high load operation, frequent cleaning, membrane component loss is serious, and eventually lead to the entire system processing capacity is seriously reduced.
In recent years, more and more types of waste are being buried in landfills, and the amount of landfill waste is getting larger and larger. The existing leachate treatment facilities are simple and inefficient, which poses a serious threat to the surrounding environment, especially the downstream water sources. In order to meet the leachate discharge standards generated by the increase of landfill waste volume, The leachate treatment plant needs to be upgraded to eliminate the threat to the surrounding environment.

Treatment scale: The wastewater of this project is mainly landfill leachate. In order to meet the standard discharge of landfill leachate generated by the increase of landfill waste volume, the leachate treatment workshop needs to be upgraded to eliminate the threat to the surrounding environment. The daily capacity of the designed landfill leachate treatment system is 150T/D, and the concentrated liquid is refilled.

Design treatment process:
After comprehensive comparison of the landfill leachate treatment process of multiple schemes, it is recommended to adopt the treatment process of "equalization tank + primary denitrification + primary nitrification + secondary denitrification + secondary nitrification +MBR membrane treatment system + nanofiltration membrane treatment system + reverse osmosis membrane treatment system", the backfilling and recharge treatment of sludge and concentrated liquid, and the natural degradation treatment of landfill.

Process characteristics
1. Two-stage nitrification and denitrification process
After the A/O process, the addition of A two-stage anoxic reactor (A pool) and A fast aerobic reactor (0 pool) is A two-stage A/0 process, the second stage A/0 is mainly used for the removal of residual nitrate and nitrogen and the excessive addition of organic matter in the secondary A pool, which also makes the process have a stronger impact load resistance. The two-stage A cell solves the problem of limited nitrogen removal capacity of A/0 process. However, the end 0 tank makes it difficult for denitrification to occur in the secondary sedimentation tank and N2 is produced to make the sludge float up.
Process features:

The process is simple, no additional carbon source and post-aeration tank is required, the original sewage is used as the carbon source, and the construction and operation cost is low;
Before denitrification, after nitrification, set up an internal cycle, using the organic substrate in the original sewage as the carbon source, the effect is good, and the denitrification reaction is sufficient;
After the aeration tank, the denitrification residue can be further removed and the quality of the treated water can be improved;
Stirring in stage A will only suspend the sludge and avoid an increase in DO. Strong aeration is adopted in the first part of section O, and the gas volume is reduced in the latter part to reduce the DO content of the inner circulating liquid, so as to ensure the anoxic state of section A.

2. MBR process
MBR is short for membrane bioreactor. It replaces the secondary sedimentation tank in activated sludge process with membrane component, which constitutes the membrane bioreactor wastewater treatment process. It is a new and efficient wastewater treatment process. In this process, because the membrane can trap almost all the biomass in the reactor, long mud age and high suspended solid concentration can be obtained, and low F/M can be maintained. According to the different arrangement of the bioreactor and the membrane components, it can be divided into separate (membrane components and independent facilities of the bioreactor) and integrated (membrane components are placed in the bioreactor). The MBR membrane bioreactor process is shown in the figure below.
Process features:

The effluent quality is good
Less residual sludge
Small footprint
Can handle difficult to degrade organic matter
Easy to operate, automatic control

3. nanofiltration process
Nanofiltration membrane: Pore size above 1nm, generally 1-2nm is a functional semi-permeable membrane that allows solvent molecules or some low molecular weight solutes or low-cost ions to pass through. It is a special and very promising variety of separation membrane, it is named for the size of the substance can be intercepted about nanometers, it intercepts the molecular weight of organic matter is about 150-500, the ability to intercept dissolved salt is between 2-98%, the univalent anionic salt solution is lower than the high anionic salt solution. It is used to remove organic matter and chroma from surface water, remove hardness from groundwater, partially remove dissolved salts, concentrate fruit juices, and separate useful substances in pharmaceuticals.
Process features:

The concentration and purification process is carried out at room temperature, no phase change, no chemical reaction, no other impurities and the decomposition and denaturation of the product, especially suitable for heat-sensitive substances.
Can remove the salt of the product, reduce the ash content of the product, improve the purity of the product, compared with solvent desalination, not only the product quality is better, and the yield can also be improved.
High yield and less loss in the process.
Acid, alkali, alcohol and other effective substances can be recovered in the solution to achieve the recycling of resources.
Equipment structure is compact, small footprint, low energy consumption.
Easy to operate, can achieve automatic operation, good stability, easy maintenance.

4. reverse osmosis process
RO membrane aperture is one millionth of the hair (0.0001 micron), generally can not be seen by the naked eye, bacteria, viruses are 5000 times its, therefore, only water molecules and some mineral ions can pass (through the ions are not beneficial to damage orientation), other impurities and heavy metals are discharged by the wastewater pipe.
Reverse osmosis membrane is the core element of reverse osmosis. It is a kind of artificial semi-permeable membrane made by simulating biological semi-permeable membrane. Generally made of polymer materials. Such as cellulose acetate membrane, aromatic polyacyl callosal membrane, aromatic polyamide membrane. The diameter of the surface micropores is generally between 0.5 and 10nm, and the size of the permeability is related to the chemical structure of the film itself. Some polymer materials have good repulsion to salt, and the penetration rate of water is not good. The chemical structure of some polymer materials has more hydrophilic groups, so the water penetration rate is relatively fast.

Process features: