How does ability achieve cement factory wastewater zero discharge more save moneyDate: 2019-09-02 Views:
With the increasingly strict environmental protection policy, the discharge requirements of cement industry wastewater are higher and higher, so the construction and upgrading of cement plant wastewater treatment facilities is imperative.In this paper, the main sources of waste water and water quality analysis, zero discharge of cement plants to take some successful measures to summarize, and share with cement peers.
1. Classification of waste water
According to the source of cement plant waste water, there are three types: living and auxiliary workshop waste water, production waste water and rain water.
2. Living and auxiliary production workshop wastewater
The waste water of living and auxiliary production workshop is mainly washing water and fecal waste water for cement factory workers. This kind of waste water contains more organic substances and disease-causing bacteria such as microorganism and escherichia coli. The BOD5 content is about 200mg/L.Usually, the wastewater is fermented and decomposed in the septic tank and collected in the sewage pipe network, and then flows to the sewage treatment station for unified treatment.However, most cement plants are far away from urban sewage treatment stations. Considering the cost and other factors, small sewage treatment stations are generally built by themselves in the initial stage of plant construction, and the simple treatment method of biochemical or physicochemical method combined with biochemical method is adopted for simple treatment before discharge.
3. Waste water production
Production wastewater mainly includes equipment maintenance drainage, waste heat power generation system drainage and laboratory wastewater.In addition to a small amount of grease and silt, the equipment maintenance drainage does not contain other harmful substances and the water amount is small. It can be directly discharged into the sewage pipe network through the oil separation tank and sedimentation tank treatment, and then into the human medium water treatment system for recycling and reuse, without discharging to the outside.
The waste water discharged from the waste heat power generation system includes the waste water discharged from the circulating pool, the waste water discharged from the water treatment and the continuous waste water discharged from the boiler.In order to achieve the zero discharge of this part of waste water, we consulted water treatment manufacturers from various sources, consulted relevant literature and finally took the following measures for treatment according to the actual situation:
(1) recycling tank to discharge sewage.
Due to the continuous evaporation of circulating cooling water during the cooling process, the salt concentration in the water increases continuously and scale is easy to form.In order to ensure the quality of cooling water, delay the time of scale formation in condenser copper pipe and improve the vacuum degree, it is necessary to continuously replenish fresh water into the pool, and a part of waste water will inevitably be generated after long-term recycling.
A self-made acid adding device was built beside the circulating water tank of cooling tower. 98% concentrated sulfuric acid was added to regulate the circulating water quality. The pH value was controlled by 7.5 ~ 8.2, and the original concentration rate was increased from 2.5 to 3.5.
Use of the existing drainage, build a concrete product pool in low-lying place, completes the anticorrosive, seepage prevention measures, to pool the circulation around 20 m3 / h of the domestic sewage are collected, by adding flocculating agent, fungicide, and scale and corrosion inhibitor chemicals such as will handle the supernatant after pump back in circulation tank used as filling water continue to cycle.
A submersible sewage pump is installed beside the tank, and the lower sludge is extracted regularly (one year or several years), which is mixed with auxiliary raw materials into the vertical grinding powder and then into the rotary kiln for collaborative disposal, without producing other pollutants.
(2) water treatment and sewage discharge, boiler continuous discharge of sewage and laboratory wastewater.T
his part of the waste water volume is relatively small, acid and alkali neutralization treatment qualified (pH value control at 6.8 ~ 8.2), directly used for raw material vertical grinding mill, humidifying tower or limestone crusher discharge pit dust spray, no longer recycling.
After taking the above measures, the waste water treatment cost is about 2.5 yuan per ton (mainly for chemical agents and electricity charges), and the finished water that can be reused after treatment is up to 85%. The remaining waste water can be used for road sprinkling, greenbelt watering and dust collection and spraying water in each storage yard, which can eliminate all waste water discharged by cement factory.According to the actual situation of cement enterprises, through certain technical transformation and investment, it is possible to reuse the sewage and achieve the goal of zero discharge of sewage.
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