Coal Chemical Water Reuse/Zero Discharge System

In response to the resource characteristics of rich coal, low oil, and poor gas in China, new coal chemical industries such as coal to oil, coal to natural gas, coal to olefins, and coal to methanol have flourished in recent years. However, the areas where new coal chemical enterprises are located are mostly ecologically fragile and water scarce. In addition, the country's environmental protection requirements continue to tighten, and it is necessary to develop zero discharge wastewater treatment technology to achieve complete reuse of wastewater and reduce environmental pollution.

Due to the high concentration and complex types of pollutants in coal chemical wastewater, including oils, phenols, ammonia nitrogen, naphthalene, anthracene, pyridine, and other pollutants, as well as poor biodegradability (B/C<0.3), it is necessary to treat coal chemical wastewater to meet the requirements for reuse. To achieve complete reuse, these substances need to be treated to improve the quality of coal chemical wastewater and prevent membrane fouling problems.

Membrane fouling blockage

The Haipu Coal Chemical Water Reuse System introduces special adsorption resin to adsorb organic matter in the biochemical wastewater after biochemical treatment and ultrafiltration, reducing COD to below 50mg/L and chromaticity to below 50, reducing pollution to the reverse osmosis membrane, reducing cleaning frequency, improving service life, and reducing operating costs; At the same time, it can enhance its water production rate (the water production rate can be increased from 45-50% to 65-70%).

In addition, it can also reduce the color and COD content of reverse osmosis concentrated water (COD less than 150mg/L), with a portion of the effluent used as make-up water for the pool circulation, and the other portion used for reverse osmosis desalination to collect reverse osmosis produced water and concentrated water.

(a) Untreated reverse osmosis membrane concentrate (b) treated by the Haipu reclaimed water system for reverse osmosis membrane concentrate

For the subsequent treatment of high salt concentrated water, the water reuse system of Haipu Coal Chemical adopts electrodialysis to treat high salt concentrated water. ED is an electrically driven process, in which cations in the solution migrate to the cathode and are blocked by the anion exchange membrane under the push of the electric field on both sides of the membrane. The migration of anions in the solution to the anode is blocked by the cation exchange membrane, and the final result is the depletion of ions in the solution. The compartment where the ions are located is called the dilute compartment, and the ions are concentrated in alternating compartments, which are called the concentrated compartment. This compartment is used for desalination, concentration, and purification of the feed solution.

The Haipu Coal Chemical Water Reuse/Zero Discharge System couples resin adsorption and biochemical treatment+ultrafiltration+deep treatment+reverse osmosis+electrodialysis and other processes to achieve the resource utilization of high salt industrial wastewater. The entire process has no liquid discharge, achieving the goal of zero discharge.