Removal of organic pollutants in coking wastewater based on coal-based adsorbents: A pilot-scale study of static adsorption and flotation

Coking wastewater mainly comes from coke oven gas primary cooling and production water during the coking production process, as well as steam condensate wastewater. Because of its complex and variable composition and poor biodegradability, it is considered one of the most difficult industrial wastewaters to treat. In this paper, four coal-based adsorbents were studied to treat coking wastewater before biological treatment (S1) and after biological treatment (S2). Coke powder showed better COD removal (60.3% in S1 and 74.0% in after S2) in the coking wastewater than coal adsorbents due to its well-developed pore structure that is more conducive to adsorption. With the coal adsorbents, Long flame coal had a relatively great adsorption performance (COD remove rate, 47.3% in S1 and 40.1% in S2) while CC exhibited the poorest performance (COD remove rate, 26.9% in CW-BBT and 23.4% in CW-BAT). In addition, the subsequent separation of the adsorbents by flotation was also investigated. Moreover, the flotation separation yield of coke powder in before biological treatment and after biological treatment is better than for the other three adsorbents. Therefore, coke powder has potential advantages in coking wastewater treatment.