ABSTRACT
The aim of this study was to investigate the role of initial external carbon source concentration on sulphate removal by four bacterial and four fungal isolates under shake flask conditions. The test wastewater was filtered and supplemented with sodium acetate as the external carbon source at respective concentrations of 5g/L, 10g/L, 15g/L and 20g/L, before dispensing in 200mL quantity in 250mL capacity conical flasks, sterilised and inoculated with the test microbial isolates. Prior inoculation and at 24h interval, for 96 h for the estimation of sulphate concentration in the wastewater using standard methods. The results revealed remarkable sulphate removal in the absence of the sodium acetate and on its 5g/L addition. An increase in the concentration of the sodium acetate caused a corresponding decrease in the level of sulphate removal. Percentage sulphate removals in presence of the test isolates were observed to range from 47.01 to 57.81%, 18.66 to 51.66%, -1.64 to 11.03%, 5,38 to 22.37% and -3.59 to 5.18%, at sodium acetate concentrations of 0g/L, 5g/L, 10g/L, 15g/L and 20g/L, respectively. This trend was irrespective of the isolates used for investigation. The study was able to provide an insight to the role of carbon concentration on sulphate removal by the test microbial isolates.
ABSTRACT
The ever increasing cost of fossil fuels and its attendant pollution menace has provided the pedigree to consider alternative sources of energy. An investigation was launched into the design and construction of an Anaerobic Digester system from locally available raw materials using local technology and the production of biogas from food wastes and Human excreta generated within a University campus. The experiment lasted for 60 days using a 40-liters laboratory scale anaerobic digester. The volume of gas generated from the mixture was 84,750cm3 and comprised of 58% CH4, 24% CO2, and 19% H2S and other impurities. The physico-chemistry of the feedstock in the digester revealed an initial drop in pH to more acidic range and a steady increase 4.52 – 6.10. The temperature remained relatively constant at mesophilic range: 22.0ºC– 30.5ºC throughout the study. The Carbon/Nitrogen (C/N) ratio of the feedstock before digestion was within 139:1. Population distributions of the microflora show aerobic and anaerobic bacteria to include Klebsiella spp, Bacillus spp, Escherichia coli, Clostridium spp and a methanogen of the genera Methanococcus. In most developing nations of Sub-Saharan Africa where biomass is abundant, and where biogas technology is in its infant stage, the anaerobic digestion system could be the much awaited solution.
ABSTRACT
Industrialization has led to huge waste generation over the last decades, the absence of adequate facilities for treating such wastes in most developing nations has led to the discharge of effluents into the environment without proper treatment. Toxicological effects of effluents from rubber processing plant (collected during the period of low rivertide i.e. between October 2012 and February 2013) were carried out in this study. Lethal concentration (96-h LC50) was evaluated using 0.25mg/L, 0.30mg/L, 0.35mg/L and 0.40mg/L while sub-lethal effects (42 days) was carried out on haematological parameters like Red Blood Cell (RBC), White Blood Cell (WBC), Haemoglobin (Hb), Packed Cell Volume (PCV), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH) and Mean Corpuscular Haemoglobin Concentration (MCHC) using 0.064mg/L, 0.048mg/L, 0.032mg/L and 0.016mg/L which are the 20%, 15%, 10% and 5% of the 96-h LC50 value. Mortality increased as the concentrations of the effluent increases and 0.32mg/L was obtained as LC50. In comparison with the control, the mean value obtained for PCV, HB and RBC showed significant differences (P<0.05) most especially at highest concentration while there was no significant difference in all values obtained for WBC, MCV, MCH and MCHC. It was concluded that the rubber processing effluent had some negative effect on the haematology of Clarias gariepinus. Therefore, it is recommended that the effluent should be properly treated before discharge into the environment.