Wastewater treatment process of Haer open-pit coal mine

        The Harbin Wusu open-pit coal mine sewage treatment plant was completed and put into operation in November 2008. It underwent renovation in 2012 and adopted a nano biochemical reaction process. Due to various reasons, the sewage treatment system could not discharge in a stable and compliant manner for a long time. In 2017, it underwent further renovation and adopted MBR sewage treatment technology. Based on the actual sewage treatment situation, this article briefly analyzes the sewage treatment process of the sewage treatment station.

1. Process unit design.

The sewage treatment process is divided into sewage treatment system, sludge treatment system, and dosing system.

(1) The sewage treatment system mainly includes pre-treatment unit, biochemical treatment unit, and advanced treatment unit according to the process.

(2) The sludge treatment system mainly concentrates and dehydrates the sludge generated during the entire sewage treatment process, treating the sludge: sludge → sludge concentration tank → box type filter press dewatering machine → sludge cake transportation and disposal.

(3) The dosing system has two sets of dosing devices, namely PAC and PAM， Two types of drugs are added to two initial sedimentation tanks. Various chemical dosing systems are quantitatively transported to each dosing point through storage tanks, dissolution units, metering pumps, and corresponding pipelines to meet the needs of stable operation of the sewage treatment process in the device. coagulants and flocculants are regularly purchased and stored for backup. The clean water required by the chemical dissolution unit is supplied by the water supply pipeline entering the sewage treatment boundary.

2. Main process analysis.

(1) In the specific process flow, the main function of aeration sedimentation is to achieve the protection of pipelines and valves by removing sand particles with a particle size of 0.2mm or more and a density greater than 2.65t/m3, thereby minimizing wear and blockage issues. Under the influence of gravity, the inflow velocity is controlled so that inorganic particles can sink and organic suspended particles can smoothly enter the next process. Under the action of aeration, pollutants in the sand particles are smoothly discharged, and combined with centrifugal action, the comprehensive effect of aeration deodorization is achieved.

(2) The main function of the sand water separator is to separate the sand water in the sand water mixture, transport the separated sand for external treatment, and return the separated water to the regulating tank.

(3) MBR water treatment, also known as membrane bioreactor, is a new type of water treatment technology that combines membrane separation units and biological treatment units in the fields of sewage treatment and water resource reuse.

(4) The air flotation process is mainly used for separating water and suspended solids, and the selected equipment includes air compressors, mixers, slag scrapers, dissolved air tanks, etc. The main function of air flotation equipment is to separate the suspended solids that are difficult to precipitate in the water after sand settling treatment, as well as the floating oil and emulsified oil in the water. By integrating the above processes, it can provide assistance for the treatment of wastewater in open-pit coal mines, meet the treatment needs of wastewater, comprehensively reduce the impact of coal mine production wastewater, ensure the environmental protection of coal mining activities, and thus comprehensively enhance the sustainable and healthy development of coal mining enterprises.