The discharge of untreated tannery wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. This present review offers a critical evaluation of bioremediation capacity of microorganisms, especially in the context of environmental protection. Furthermore, this article discussed the biosorption capacity with respect to the use of bacteria, fungi, biofilm, algae, genetically engineered microbes, and immobilized microbial cell for the removal of heavy metals. The use of biofilm has showed synergetic effects with many fold increase in the removal of heavy metals as sustainable environmental technology in the near future.

Abstract:The tannery industry is renowned for the huge amount of toxic solid and liquid waste generated from the cleaning, fleshing, splitting, tanning, shaving and buffing of raw materials. Biomass briquettes are a proven way of generating energy from waste. This study investigates the development and characterization of biomass briquettes from tannery solid wastes (TSWs). TSWs, which comprise hair, flesh, chrome shavings and buffing dust, were collected from a tannery in Kano, Nigeria, to formulate and characterize six briquettes. Scanning electron microscopy and proximate analysis were carried out on the samples. The six briquettes, comprising varying ratios of hair, flesh, chrome shavings and buffing dust, were molded and characterized. Thermal efficiency, durability and compressive strength, among other properties, were determined for the six briquette formulations. The briquettes developed had calorific values between 18.632 and 24.101 MJ/kg. Durability of the briquettes ranged from 98.12% to 99.77%. The energy values were within the range of 17.462-24.101 MJ/kg, which was comparable to other fuel sources such as sub-bituminous coal (20.000-24.730 MJ/kg). This study shows that TSWs can be used for fuel briquette production, which is a source of sustainable energy generation. It is environmentally friendly, cost effective and affordable compared to fossil fuel.

The quest for an effective alternative means for effluent treatment is a major concern of the modern-day scientist. Fungi have been attracting a growing interest for the biological treatment of industrial wastewater. In this study, Saccharomycescerevisiae and Torulasporadelbrueckii were isolated from spoiled watermelon and inoculated into different concentrations of effluent. The inoculants were incubated for 21-days to monitor the performance of the isolates by measurement of biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrates, conductivity, phosphates, sulphates and turbidity. The results showed that Saccharomycescerevisiae had the highest percentage decrease of 98.1%, 83.0%, 60.7%, 60.5%, and 54.2% for turbidity, sulphates, BOD, phosphates and COD, respectively, of the tannery effluent. Torulasporadelbrueckii showed the highest percentage decrease of 92.9%, 90.6%, and 61.9% for sulphates, COD, and phosphates, respectively, while the syndicate showed the highest percentage reduction of 87.4% and 70.2% for nitrate and total dissolve solid (TDS), respectively. The least percentage decrease was displayed by syndicate organisms at 51.2%, 48.1% and 40.3% for BOD, COD and conductivity, respectively. The study revealed that Saccharomycescerevisiae and Torulasporadelbrueckii could be used in the biological treatment of tannery-effluent. Hence, it was concluded that the use of these organisms could contribute to minimizing the adverse environmental risks and health-hazards associated with the disposal of untreated tannery-effluents.

BackgroundPathophysiological investigation of disease in a suitable animal model is a classical approach towards development of a credible therapeutic strategy. This study examined appropriate insulin level in selecting animal model for type 2 diabetes (T2D) studies.MethodAlbino Wistar rats (150-200g) were divided into two groups fed with commercially available normal-diet-feed (NDF) and water or fortified diet feed (FDF) (10g NDF per gram of margarine) with 20% fructose solution as drinking water. After 6 weeks of dietary regimen both groups were divided into 5 sub-groups and injected intraperitoneally with a graded dose of streptozotocin (STZ) (0, 25, 35, 45 & 55mg/kg bw.).ResultThe result showed that the FDF-fed rats increased significantly in body weight, basal serum insulin, total cholesterol, triglycerides and blood glucose levels as compared to NDF-fed rats. Ten days post STZ induction, the groups treated with STZ (45 & 55 mg/kg) developed frank hyperglycaemia with < 46.8% serum insulin, a severe deficiency typical of diabetes type 1. The NDF25 and NDF35 groups with 75.7% and 64.4% serum insulin respectively presented relative normoglycemia, whereas the FDF35 (85.8% serum insulin) were notably hyperglycaemia (>300 mg/dL) throughout the 6weeks post diabetes confirmation. These FDF35 rats were sensitive to glibenclamide, metformin and pioglitazone in lowering hyperglycaemia, hypertriglyceridemia and hypercholesterolemiaConclusionThe hyperglycaemia stability of the FDF35 rats (85.5% insulin) together with their sensitivity to 3 different hypoglycaemic drugs strongly suggests their suitability as a non-genetic model of T2D. Hence the study shows that circulating serum insulin ≥ 85.8% with overt hyperglycaemia may be utilized as the benchmark in selecting rat models for T2D studies.