Removal of detergents by activated petroleum coke from a clarified wastewater treated for reuse

The removal of detergents from clarified wastewaters by activated petroleum coke (CAPA) was assessed. These substances, owing to their foamy properties, constitute a problem for ammonia removal by the air stripping process that could be installed in a wastewater treatment train to produce reclaimed water. CAPA was evaluated as a more economical alternative than a commercial activated carbon. Experimental work was divided in three stages: 1) production and characterisation of materials; 2) pretreatment of raw wastewater through the Fenton's reagent or coagulation-flocculation process with Al2(SO4)3; and 3) adsorption and bio-adsorption tests of clarified effluents. These tests were carried out in the laboratory in discontinuous and continuous reactors, the former by the "point-by-point" technique, with and without a previous fixing of bacteria, and the latter by the Rapid Small Scale Column Test. Detergents content, color, COD and UV254nm were measured in raw and treated wastewaters. Results show that the best pretreatment for the adsorption process was coagulation-flocculation rather than Fenton's method. Oxidation by this process decreased the adsorptive properties of detergents. Biomass fixed on the CAPA particles significantly increased the UV254nm and COD removal efficiencies (20% and 170% respectively). The breakthrough curves showed that CAPA could attain the expected detergents removal efficiency (66%) for the alum effluent.