Coal Chemical Coking RO Concentrated Water Treatment

Coking wastewater is generated by the recovery of by-products such as tar and benzene during the production process of coke and gas obtained from high-temperature coal cracking. Coking wastewater has a very complex composition and high concentration, containing common organic pollutants such as quinoline, indole, pyridine, phenols, and biphenyl, as well as inorganic pollutants such as fluoride ions, ammonia nitrogen, and cyanide. It is a typical toxic wastewater that is difficult to degrade and biodegrade.

In order to meet the requirement of non discharge of coking wastewater, various coal chemical enterprises have conducted extensive research on the treatment of coking wastewater based on membrane separation technology. In this process route, after biochemical treatment, the vast majority of organic matter in the coking wastewater is effectively removed. This wastewater is treated by ultrafiltration, nanofiltration, and reverse osmosis to obtain pure reuse water, which can reuse 90% of the coking wastewater.

However, due to the low COD removal rate of ultrafiltration, the COD of the wastewater entering reverse osmosis is still relatively high (about 100-400 mg/L), with a large color and often problems such as membrane fouling and short lifespan. It is necessary to regularly clean and replace the membrane, which undoubtedly increases operating costs;

At the same time, many reverse osmosis systems have a decent initial water quality, but soon the quality of the produced water gradually deteriorates and cannot meet the standards for production reuse; In addition, the organic content (COD generally around 1000 mg/L) and chromaticity of reverse osmosis concentrated water are still relatively high, requiring additional treatment and making it difficult.

In addition, for the concentrated water produced by nanofiltration and reverse osmosis, due to the presence of difficult to degrade organic matter and a large amount of inorganic substances, further treatment is difficult and costly.

Haipu has developed a DEEP process based on resin technology water purification using "ultrafiltration+deep adsorption+reverse osmosis" to efficiently achieve water resource reuse, in response to the deep treatment and reuse needs of coal chemical coking wastewater and the characteristics and difficulties of wastewater in related industries.

Introducing deep adsorption between dual membranes, due to the high adsorption capacity, stability, and easy regeneration ability of nano adsorbents, they can adsorb organic matter in biochemical wastewater, reducing COD to below 50mg/L and chromaticity to below 50, avoiding fouling of reverse osmosis membranes, reducing cleaning times, improving service life, and reducing operating costs.

At the same time, it can enhance its water production rate (the single-stage RO water production rate can be increased from 45-50% to 65-70%), ensuring high-quality water that can be reused. In addition, it can also make reverse osmosis concentrated water colorless, with low COD, and can be directly discharged or further evaporated to obtain by-product salt, achieving near zero discharge of wastewater.