Evaluating tannery wastewater treatment performance based on physicochemical and microbiological characteristics: An Ethiopian case study

Abstract

Tanneries are an important industrial sector in Ethiopia; consequently, gaps in wastewater treatment process performance need to be identified as the country increases its emphasis on compliance. A case study was conducted to evaluate physicochemical and microbial water quality at a tannery near Addis Ababa. The treatment process was designed for the following: sulfide oxidation; biological oxygen demand reduction; and chromium removal. While some of Ethiopia's standards for industrial wastewater treatment were met through treatment, effluent COD, sulfide, total nitrogen, and total chromium guidelines were not. 16S rRNA gene analysis was used to evaluate the microbial community composition across the treatment train. The results show that common ruminant phyla were dominant throughout, with Firmicutes and Bacteroidetes comprising 77% to 82% relative abundance. The Firmicutes Clostridium increased consistently in relative abundance with treatment, comprising 39% to 61% of the total bacterial community in the effluent. Improved treatment is needed to meet environmental and public health goals. Practitioner Points Case Study of tannery wastewater treatment in Ethiopia shows ineffective treatment of chemical pollutants. Microbiological pollutants from tannery wastewater systems can introduce agents of importance to public health The microbiological composition of tannery influent, mixed liquor and effluent contains mostly four bacterial phyla lead by Firmicutes. Most pathogenic bacterial genera found in the tannery wastewater treatment system became a decreasing percentage of the total population. Clostridium comprises up to 61% of the effluent bacterial population and deserves further evaluation to better understand the consequences of its dominance.

Conversion of Tannery Solid Wastes into Fuel Briquettes Using Wastepaper as a Binder

“…Currently over 30 tanneries are in operation in Ethiopia, most of which use the conventional chromium-based tanning method [6,17]. It was reported that the country generates 70,104 MT of pretanned leather waste annually, disposing of it using conventional methods such as landfills and incineration [18].…”

Comparative Removal of Cr(VI) and F− Ions from Water by Freezing Technology

“…us, surface and groundwater contamination is a persisting challenge in many countries. However, the problems are being exacerbated in developing countries that lack ternary treatments for their industries [12]. Cr(VI) has been shown to have genotoxicity, mutagenicity, and even cause cancer in humans [13,14].…”