Pilot-scale study on anaerobic/aerobic treatment of a textile dye wastewater

A pilot-scale system was constructed at the Martinsville Publicly Owned Treatment Works (POTW) in Martinsville, Virginia, to evaluate an anaerobic/aerobic treatment scheme for removal of color from textile dye waste waters mixed with municipal sewage. Treatments were evaluated with and without addition of a reducing agent (thiourea dioxide) after anaerobic treatment utilizing 6 and 12 hour anaerobic hydraulic retention times (HRT). Polymer treatment of the aerobic effluents and toxicity of the wastewaters to Ceriodaphnia dubia and Pimephales promelas were studied. In addition, the benefits of polymer treatment of anaerobic effluent, prior to aerobic treatment, were evaluated in a lab-scale system utilizing continuous flow biological reactors (CFBRs).

Wastewater samples were collected throughout the treatment schemes and analyzed for: color, total organic carbon (TOC), 5-day biochemical oxygen demand (BODs), chemical oxygen demand (COD), total phosphorus, sulfide, sulfate, total Kjeldahl nitrogen (TKN), ammonia, nitrate, chloride and oxidation-reduction potential (ORP). Nearly 50% color removal was observed during anaerobic treatment with a 12 hour HRT, with a total system color removal, including subsequent aerobic treatment, of about 53%.