Application of Oxidation Pond Wastewater Treatment Technology in Changchun Passenger Car Factory

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1 Application of Oxidation Pond Sewage Treatment Technology in Changchun Passenger Car Factory

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1 Background information and technological process

Changchun Passenger Car Factory is the main base for the production of railway passenger cars and underground electric passenger cars in China.
It consumes 2.
1 million tons of water annually, and has a total discharge of 1.
8 million tons of mixed sewage from production and domestic life
.

The drainage system of the plant area is divided into two parts: the east and the west.

Figure 8-8 Process flow of advanced sewage treatment and reclaimed water reuse in Changchun Bus Plant

Sewage flows into the advective grit chamber through the pipeline.

Thick and fine grids are set before and after the grit chamber to trap coarse debris; an overflow well is set in front of the grit chamber to discharge rainwater and accidents in summer to prevent the rear The impact of the sewage treatment system

Table 8-11 Water Quality Index Unit of Inlet and Outlet Water of Oxidation Pond: mg/L (except pH value)

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After more than 3 years of use and operation, it has been shown that the quality of reused water meets the requirements of industrial cooling cycle water quality and domestic miscellaneous water quality standards
.

At present, the total amount of reclaimed water used by the factory has reached 700,000 tons, saving the factory an annual cost of 3.

In view of the poor biochemical characteristics of the oxidation pond effluent, air flotation, filtration, and disinfection were selected as the main equipment treatment processes to reprocess the oxidation pond effluent
.

At the same time, taking into account the adverse effects of oil and some coarse particles in the sewage in the central and western areas of the factory on the treatment system, a pretreatment sand and oil trap was added before the oxidation pond

Part of the effluent from the oxidation pond is then lifted by a pump and enters the air flotation filter tank for reuse treatment, and the rest of the unused part is discharged into the municipal pipeline outside the plant through the pipeline
.

The air flotation tank adopts the advection design, and basic aluminum chloride coagulant is added to the forward water pipe of the air flotation tank to perform coagulation and air flotation on the sewage

Table 8-12 Unit of effluent quality monitoring results; mg/L (except pH value)

Through several years of actual operation, the summary of experience is as follows
.

(1) To improve the treatment efficiency of oxidation ponds, it is necessary to strengthen atmospheric reoxygenation
.

For this reason, we planted reeds in the oxidation pond, and gradually determined the spacing of the reeds reasonably, and made full use of the oxygen transfer capacity of the reed stems to improve the reoxygenation efficiency

(2) Oxidation ponds rely on the reproduction and growth of lower plant algae to remove organic matter in sewage
.

Therefore, the number and types of algae will affect the effect of the oxidation pond on sewage treatment

(3) The dosage of coagulant should be controlled strictly according to the suspended solids in the effluent of the oxidation pond, generally 40g per cubic meter of sewage
.
Double-layer filtering equipment should be backwashed in time to avoid clogging of the filter material and loss of filtering effect, which will affect the use effect of the reused reclaimed water
.
Regularly inspect and maintain power equipment such as water pumps, foam scrapers, and air compressors
.

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3 Costs and benefits

The Changchun Bus Plant's wastewater treatment reclaimed water reuse project can reduce emissions to the environment every year based on the recent reuse of 2000t/d of reclaimed water: COD is 140t, SS is 160t; petroleum is 6t, and the environmental benefits are very obvious
.

Through the final cost accounting of the electricity consumption, pharmaceutical costs, labor costs, management fees and equipment depreciation costs for the normal operation of the treatment facilities, the waste water treatment reuse cost is 0.
8 yuan/m ³ , while the factory uses the tap water cost The price is 2.
5 yuan/m ²
.
This shows that every 1m ³ of reclaimed water can save the factory 1.
7 yuan, and according to this calculation, it can directly save 1.
24 million yuan for the factory every year
.
Considering the reduction or exemption of sewage charges and municipal facilities drainage fees, the project can obtain an indirect economic benefit of 350,000 yuan for the factory
.
The comprehensive economic benefits can save more than 1.
6 million yuan for the factory every year, and it is expected that the entire investment can be recovered in about 4 years
.