International Journal of Environment, Agriculture and Biotechnology (IJEAB) Vol-2, Issue-6, Nov -Dec- 2017 http://dx.doi.org/10.22161/ijeab/2.6.10 ISSN: 2456-1878 Treatment of Tannery Wastewater to Remove Hazardous Pollutants by Scoria (Volcanic ash) a Low cost Adsorbent Mekonnen Birhanie, Seyoum Leta, Mohammed Mazharuddin Khan Center for Environmental Sciences, Addis Ababa University, Addis Ababa, Ethiopia Abstract — In present study Scoria, a volcanic ash INTRODUCTION identified as potentially efficient low-cost and locally 1.1 Introduction: Tanning is one of the oldest industries available filter media as an adsorbent for the treatment of in the world Tannery effluent is among one of the most tannery wastewater and investigated as a filter media for hazardous pollutants of industry. Major problems caused tannery wastewater treatment with selected by tannery wastewater containing heavy metals, nutrients, physicochemical parameters. This study had been toxic chemicals, chloride, lime with high dissolved and conducted in Addis Ababa University from May to August suspended salts, and other pollutants. 2016.The volcanic rocks were collected from volcanic With the growth of population, the increasing requirement cones of refit valley area of Oromia region, Ethiopia and of leather and its products led to the establishment of their chemical characteristics were determined using large commercial tanneries. Tanneries are typically XRF analysis. Batch mode comparative experimental characterized as pollution intensive industrial complexes study design has been carried out. The filter media was which generate widely varying, high-strength crushed and graded and effective size was determined by wastewaters. Nearly 30 m3 of wastewater is generated using standard sieve. The composite sample of during processing of one tone of raw skin/hide [1]. wastewater was collected from Dire tannery, Addis Tannery operation consists of converting of the raw hide Ababa Ethiopia. The physicochemical analysis of or skin into leather which consume huge amount of water wastewater samples has been done before and after 24, in several stages, generating an enormous amount of 48, and 72 hours treatment using standard methods. liquid effluents which are hazardous to the environment Mean and standard deviations were calculated for each to which they are discharged, consequently, make it as a parameter. R statistical software was run for data potentially pollution intensive industry. Tannery effluents analysis. Based on this investigation, characterization of again compromise the physical, chemical and biological the untreated tannery wastewater revealed that the mean properties of aquatic environment. Apart from the most concentration of BOD5, COD, TSS or orthophosphate, toxic heavy metals like Chromium (Cr) chemical ammonium, nitrite, nitrate, sulfide, sulfate and chromium impurities of tannery effluents mostly includes the were 1081±159.55, 12913±6874.7, 2426±515.2, 168±74, following dissolved substances such as inorganic salt 2 314±59.9, 1.7±0.29, 124±12.8, 417±130.7, 1307±224 and cations (Fe, Zn, Cu, Ca, Na, etc.); anions such as SO4 , - 3- 35.7±8.6 mg/l respectively. Nitrate removal efficiency of NO3 , PO4 and parameters such as, BOD, COD, TSS, scoria was 99% at RT= 72 hours. However phosphate TDS etc.[2]. Therefore treating tannery wastewater using removal was better by scoria on the first 24 and 48 hours natural adsorbents is very important to protect the but then again at RT=72hours scoria removes 63% only. surrounding environment. The efficiency of scoria shows from 75-77%. In the first In Ethiopia Currently, there are more than 30 tannery 24 and 48 hours retention time scoria achieved 71% industries in operation. Among them the majority found chromium reduction. Considering all the selected tannery in Oromia region especially Mojo town and around six wastewater parameters for this study, the average established in the capital city Addis Ababa. These treatment efficiency of scoriawas58.8% and 63.4% at tanneries have 153,650 sheep and goat skin soaking RT=24 hours, and 67.5% at RT= 48 hours respectively capacity and 9,725 cowhides soaking capacity per day. and equivalent result (68.3%efficiency)was obtained after Together they also employ 4577 persons [3]. 72 hours. The results shows scoria substrates has a The total wastewater discharge estimation from tanneries potential to treat tannery wastewater. is about 400 million m3/year. About90% of world leather Keywords— Tannery Wastewater, Scoria, Filter Media, production uses chrome-tanning processes rather than Removal efficiency, Wastewater parameters. vegetable tanning [4]. In Chrome tanning process www.ijeab.com Page | 2841 International Journal of Environment, Agriculture and Biotechnology (IJEAB) Vol-2, Issue-6, Nov -Dec- 2017 http://dx.doi.org/10.22161/ijeab/2.6.10 ISSN: 2456-1878 tanneries utilize chromium in the form of basic 1.2 Adsorbents and Adsorption in Wastewater chromium-sulphate for hide stabilization against Treatment Technology: Adsorption is recognized as one microbial degradation and provision of flexibility of the of the most effective purification and separation technique leather. In chrome tanning process about 60% - 80% of used in industry especially in water and wastewater chromium reacts with the hides and about 20%- 40% of treatment. Although the commercially available the chromium amount remaining in the solid and liquid adsorbents are efficient in removal of heavy metals, they wastes. are costly and some cannot be regenerated and recycled. Tanneries generate wastewater in the range of 30 – 35 A number of approaches have been recently studied for liter per kilogram of skin or hide processed with variable the development of cheaper and more effective adsorbents pH and high concentrations of suspended solids, BOD for metal removal. Many non-conventional low cost and COD. Major problems are due to wastewater adsorbents, including natural materials, bio-sorbents, and containing heavy metals, toxic chemicals, chloride, lime waste materials have been studied and proposed by with high dissolved and suspended salts and other several researchers [8]. pollutants [5]. Hexavalent chromium from tannery Adsorption is a user-friendly technique especially for the wastewater is one of the major concerns of environmental removal of heavy metals. This process seems to be most pollution. This is due to discharge of tannery wastewater versatile and effective method for removal of heavy metal in large quantities without or with partial treatment [6]. [9]. The adsorption process is being widely used by Developing countries face numerous challenges related to various researchers for the removal of heavy metals [10] preserving the environment from industrial wastewater from waste streams and activated carbon has been pollution. Like many other developing countries, Ethiopia frequently used as an adsorbent. Despite its extensive use also grieve from environmental pollution problems of in the water and wastewater treatment industries, wastewater particularly Tannery industrial wastewater. activated carbon remains an expensive material. In recent This issue seems to be a subject which has not yet years, the need for safe and economical methods for the received adequate attention during the development of elimination of heavy metals from contaminated waters Tannery industries. Certainly very little and/or no has necessitated research interest towards the production investment has been made in the past to wastewater of low cost alternatives to commercially available treatment facilities compared to drinking water supply. activated carbon. Therefore, there is a need to develop an efficient and low- Efficient methods of chromium removal from wastewater cost wastewater treatment technologies for the removal of are important to attain environmental quality standards. heavy metals and other pollutants. Among these Adsorption has been identified as one of the most technologies, adsorption is a user-friendly technique for promising method for removal of dissolved heavy metal this purpose. from wastewater [11]. It has an advantage over other Adsorption has been identified as one of the most conventional methods due to its sludge free clean promising mechanism for removal of dissolved heavy operation. Although commercial adsorbents are available metal fractions and nutrients from wastewater. Although for use in adsorption, they are very expensive, resulting in commercial adsorbents are available for use in adsorption, various new low cost adsorbents being studied by they are very expensive, resulting in various new low-cost researchers. Babel and Kurniawan [7], reviewed the adsorbents being studied by researchers. Babel and technical feasibility of various low-cost adsorbents for Kurniawan [7], reviewed the technical feasibility of heavy metals removal from wastewater and concluded various low-cost adsorbents for heavy metals removal that the use of low-cost adsorbents may contribute to the from wastewater and concluded that the use of low-cost sustainability of the surrounding environment and offer adsorbents may contribute to the sustainability of the promising benefits for commercial purpose in the future. surrounding environment and offer promising benefits for 1.3 Scoria as a low-cost Adsorbent: The volcanic ash commercial purpose in the future. scoria generally denser. Scoria is somewhat porous Therefore identifying potentially efficient low-cost and material with high surface area and strength with density