Removal of PAHs, TSS, oils and fats from ammonium-rich coke wastewater by granular filtration

• Published in: Journal of environmental management Vol. 358; p. 120812
• Main Authors: Jesús, Rodríguez-Iglesias, Laura, Megido, Yolanda, Fernández-Nava, Beatriz, Suárez-Peña
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2024
• Subjects: Airlift sand filter; Ammonium Compounds - analysis; Cationic flocculant; Coke; Fats - analysis; Fats - chemistry; Filtration; Oils - chemistry; Polycyclic Aromatic Hydrocarbons - analysis; Pre-treatment; Sand speed; Stripping; Waste Disposal, Fluid - methods; Wastewater - chemistry; Water Pollutants, Chemical - analysis; Stripping; Sand speed; Cationic flocculant; Pre-treatment; Airlift sand filter
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.120812

Coke wastewater is a complex industrial wastewater due to its high content of toxic compounds such as cyanides, thiocyanates, phenols, tar, oils, and fats. After a series of treatments, wastewater with a high ammonium content is obtained (around 4,150 mg·L-1). A stripping process is used to reduce it. Certain pollutants in the influent, such as tar, polycyclic aromatic hydrocarbons (PAHs), oils, fats and total suspended solids (TSS), interfere with stripping and therefore must be previously removed. In this study, the performance of a pilot-scale airlift sand filter was evaluated under real conditions for the reduction of the concentration of tar, PAHs, oils, fats and TSS, before stripping. Prior to the sand filter, a cationic flocculant was added to the influent (2 ppm). High (10 mm.min-1), medium (7.5 mm.min-1) and low sand speeds (1.9-2.6 mm.min-1) were assessed. The latter conditions gave the best results: a decrease of 98.2% in TSS, 99.7% in oils, fats and grease and 97.6% in PAHs. The final effluent (≤ 1.6 mg PAHs·L-1, ≤ 5 mg TSS·L-1 and ≤ 0.05 mg·L-1 of fats, oils and grease) was suitable for the stripping process. •Coke wastewater is obtained after a complex scrubbing process of raw coke oven gas.•The coke wastewater stands out by the presence of tar, PAHs, oils, fats and TSS.•To reduce these pollutants, an airlift sand filter was used with flocculant dosing.•The removal achieved up to 98.2% in TSS, 99.7% in oils and fats and 97.6% in PAHs.