Treatment of Tannery Wastewater to Remove Hazardous Pollutants by Scoria (Volcanic ash) a Low cost Adsorbent

In present study Scoria, a volcanic ash identified as potentially efficient low-cost and locally available filter media as an adsorbent for the treatment of tannery wastewater and investigated as a filter media for tannery wastewater treatment with selected physicochemical parameters. This study had been conducted in Addis Ababa University from May to August 2016.The volcanic rocks were collected from volcanic cones of refit valley area of Oromia region, Ethiopia and their chemical characteristics were determined using XRF analysis. Batch mode comparative experimental study design has been carried out. The filter media was crushed and graded and effective size was determined by using standard sieve. The composite sample of wastewater was collected from Dire tannery, Addis Ababa Ethiopia. The physicochemical analysis of wastewater samples has been done before and after 24, 48, and 72 hours treatment using standard methods. Mean and standard deviations were calculated for each parameter. R statistical software was run for data analysis. Based on this investigation, characterization of the untreated tannery wastewater revealed that the mean concentration of BOD5, COD, TSS or orthophosphate, ammonium, nitrite, nitrate, sulfide, sulfate and chromium were 1081±159.55, 12913±6874.7, 2426±515.2, 168±74, 314±59.9, 1.7±0.29, 124±12.8, 417±130.7, 1307±224 and 35.7±8.6 mg/l respectively. Nitrate removal efficiency of scoria was 99% at RT= 72 hours. However phosphate removal was better by scoria on the first 24 and 48 hours but then again at RT=72hours scoria removes 63% only. The efficiency of scoria shows from 75-77%. In the first 24 and 48 hours retention time scoria achieved 71% chromium reduction. Considering all the selected tannery wastewater parameters for this study, the average treatment efficiency of scoriawas58.8% and 63.4% at RT=24 hours, and 67.5% at RT= 48 hours respectively and equivalent result (68.3%efficiency)was obtained after 72 hours. The results shows scoria substrates has a potential to treat tannery wastewater.