S.O. Dahunsi

Fertilizer and sanitary quality of digestate biofertilizer from the co-digestion of food waste and human excreta.

This research was aimed at assessing the fertilizer quality and public health implications of using digestate biofertilizer from the anaerobic digestion of food wastes and human excreta. Twelve (12) kg of food wastes and 3kg of human excreta were mixed with water in a 1:1 w/v to make 30-l slurry that was fed into the anaerobic digester to ferment for 60days at mesophilic temperature (22-31°C). Though BOD, COD, organic carbon and ash content in the feedstock were reduced after anaerobic digestion by 50.0%, 10.6%, 74.3% and 1.5% respectively, nitrogen, pH and total solids however increased by 12.1%, 42.5% and 12.4% respectively. The C/N ratios of the feedstock and compost are 135:1 and 15.8:1. The residual total coliforms of 2.10×10(8)CFU/100ml in the digestate was above tolerable limits for direct application on farmlands. Microbial analysis of the digestate biofertilizer revealed the presence of Pseudomonas, Klebsiella, Clostridium, Bacillus, Bacteroides, Penicillum, Salmollena, and Aspergillus. Klebsiella, Bacillus, Pseudomonas, Penicillum and Aspergillus can boost the efficiency of the biofertilizer through nitrogen fixation and nutrient solubility in soils but Klebsiella again and Salmollena are potential health risks to end users. Further treatment of the digestate for more efficient destruction of pathogens is advised.

Comparative evaluation of biogas production from Poultry droppings, Cow dung and Lemon grass.

The study explored the production of biogas from Lemon grass, Cow dung and Poultry droppings. The three substrates were pre-fermented according to standard methods. Six (6) kg of each pre-fermented substrate was mixed with water in ratio 1:1 v/v to form slurry and digested for 30days. A total of 0.125m(3), 0.191m(3) and 0.211m(3) of biogas were respectively produced from the Lemon grass, Cow dung and Poultry droppings with deviations of 0.00234m(3), 0.00289 m(3) and 0.00484 m(3) respectively. The cooking test carried out revealed that the scrubbed gas had higher cooking rates for water (0.12L/min, 0.085L/min and 0.079L/min for Lemon grass, Cow dung and Poultry droppings respectively) while the cooking rates for unscrubbed gas were 0.079L/min, 0.064L/min and 0.06L/min respectively. The pH of the medium fluctuated optimally between 6.5 and 7.8. The research demonstrated that Lemon grass produced less volume but better quality biogas compared to Cow dung and Poultry droppings.

Drinking Water Quality and Public Health of Selected Towns in South Western Nigeria

This study was aimed at establishing a water quality database in the study area where none existed previously. Groundwater samples from bore-holes, hand-pump, and hand-dug wells of four densely populated towns in South-Western Nigeria were analyzed in respect to physicochemical factors, biological factors, and the metals Nickel (Ni), Lead (Pb), Cadmium (Cd), Zinc (Zn), Copper (Cu), and Iron (Fe) for six consecutive months from September 2012 to February 2013 to give mean values for each town and water source. Total aerobic plate, total coliform bacteria, and Escherichia coli (E. coli) were detected in most of the water samples from the different towns and sources considered. Except for total suspended solids and total solids, the physicochemical parameters of all the samples were within permissible limits. The concentrations Pb, Ni, Cr, and Cd were above the minimum permissible limits. The presence of coliforms and E. coli in the groundwater samples indicates fecal contamination. The microorganisms isolated in this study include Enterobacteriaceae, Staphylococcus aureus, E. coli, Citrobacter, Klebsiella, Pseudomonas, Bacillus, and Micrococcus species. The analysis of variance of data obtained from this study shows that bore-hole water samples were safer for drinking that water samples from hand-pump, and hand dug wells across the communities.

Mesophilic anaerobic co-digestion of poultry dropping and Carica papaya peels: Modelling and process parameter optimization study.

The study evaluated anaerobic co-digestion of poultry dropping and pawpaw peels and the optimization of important process parameters. The physic-chemical analyses of the substrates were done using standard methods after application of mechanical, thermal and chemical pre-treatments methods. Gas chromatography analysis revealed the gas composition to be within the range of 66-68% methane and 18-23% carbon dioxide. The study equally revealed that combination of the different pre-treatment methods enhanced enormous biogas yield from the digestion. Optimization of the generated biogas data were carried out using the Response Surface Methodology and the Artificial Neural Networks. The coefficient of determination (R(2)) for RSM (0.9181) was lower compare to that of ANN (0.9828). This shows that ANN model gives higher accuracy than RSM model for the current. Further usage of Carica papaya peels for biogas generation is advocated.

Comparative biogas generation from fruit peels of fluted pumpkin (Telfairia occidentalis) and its optimization

This study evaluated the potentials of fluted pumpkin fruit peels for biogas generation using three different pre-treatment methods (A, B, C) and the optimization of its process parameters. The physic-chemical characteristics of the substrates revealed it to be rich in nutrients and mineral elements needed by microorganisms. Gas chromatography analysis revealed the gas composition to be within the range of 58.5±2.5% Methane and 27±3% Carbon dioxide for all the three digestions. The study revealed that combination of three pre-treatment methods enhanced enormous biogas yield from the digested substrates as against the use of two methods and no pre-treatment experiment. Optimization of the generated biogas data revealed that RSM predicted higher gas yield than ANN, the latter gives higher accuracy and efficiency than the former. It is advocated that fluted pumpkin fruit peels be used for energy generation especially in the locations of its abundance.

Pretreatment optimization, process control, mass and energy balances and economics of anaerobic co-digestion of Arachis hypogaea (Peanut) hull and poultry manure

The study explored biogas production from the co-digestion of Arachis hypogaea hull and poultry droppings. Mechanical and thermo-alkaline pretreatments were applied to a sample of the mixture. Another sample was treated mechanically but without thermo-alkaline methods. Optimization was done using the Response Surface Methodology (RSM) and the Artificial Neural Networks (ANNs). The optimal values for each of the five major parameters optimized are Temperature of 32.00°C, pH of 7.62, Retention time of 30.00 day, Total solids of 12.00g/kg and Volatile solids of 10.00g/kg and the predicted biogas yield for RSM was 3903.1510-3m3/kg TSfed and 3338.310-3m3/kg TSfed for ANNs in the thermo-alkaline pretreated experiment. Gas chromatography show the CH4 and CO2 content of biogas generated to be 65.5±1.5%; 26±1% and 53±1%; 26±2% respectively. The co-digestion of peanut hull with poultry droppings and other energy-yielding substrates is further encouraged.

Toxicological assessment of fish (Clarias gariepinus) from bitumen-polluted River Oluwa, Nigeria

Toxicological evaluation of Clarias gariepinus from bitumen-polluted River Oluwa, Nigeria, was carried out in furtherance of studies on the environmental impacts of the bitumen exploration in Ondo State, Nigeria. Samples were taken from three different (two polluted and one as control) sites. The effect of changes in monthly seasonal flow rate was assessed for the sites of study. Blood plasma clinical–chemical parameters (BCCPs) and histological changes/lesions in various organs were evaluated as markers of pollution in the fish blood using standard methods. The result of the physicochemical properties of water from the sampling points revealed some of the values conforming to approved standards while others showed deviation. Significant differences were found in the blood and histological endpoints between the control and the polluted sites as well as between the two seasons evaluated across the sites. The public health implications of consuming this fish are fully discussed.

Effect of Temperature on Sulphate Removal from Was tewater bySelected Bacterial and Fungal Species

The aim of thisstudy was to investigate the effect of temperature on sulphate removal from wastewater by selected bacterial ( Pseudomonas spp., Klebsiellaspp., Staphylococcus spp. andLysinibacillusspp.) and fungal ( Aspergillus niger,Aspergillus flavus,Fusarium spp.and Absidiaspp.) isolates. The study was carried out under shake flasks conditions at incubation temperatures of 30 ∫C, 35∫C, 40∫C and 45∫C at shaking speed of 150 rpm. After inoculation with the respective isolates, aliquot wastewater samples were aseptically removed from each flask prior inoculation and every 24 h, for 96 h for the estimation of sulphate levels in the wastewater and pH, using standard procedures. The results revealed optimum temperatures for sulphate removal to range from 30∫C -35∫C and 30∫C �40∫C, for the bacterial and fungal isolates, respectively. Also observed was a consistent increase in pH of the wastewater throughout the period of incubation. This trend was irrespective of the test microbial isolates and the incubation temperature.The study was able to reveal the role of temperature in sulphate removal ability of the test isolates under the experimental conditions used for investigation.

Investigation of the Efficiency of Selected Bacterial and Fungal Species in the Removal of Phosphate and Sulphate from Wastewater

The aim of this study was to ascertain the efficiency of selected bacteria (Pseudomonas, Staphylococcus, Klebsiella and Lysinibacillus species) and fungi (Aspergillus niger, Aspergillus flavus, Fusarium and Absidia species) in the removal of phosphate and sulphate compounds from wastewater. The study was carried out under shaking flasks conditions. The test wastewater was filtered, sterilised and inoculated with the respective test bacterial and fungal isolates. Just after inoculation with a test isolate and every 24 h for 96 h, aliquot wastewater sample was taken from each flask aseptically for the estimation of phosphate and sulphate concentration in the wastewater. The results revealed remarkable phosphate and sulphate removal within the first 24 h and 48 h, respectively of incubation in the presence of three of the bacterial (Pseudomonas, Staphylococcus and Klebsiella) isolates, after which increases were observed. In the presence of the fungal isolates, remarkable decreases in phosphate and sulphate levels in the wastewater were observed after the first 48 h of incubation in the presence of the Aspergillus niger and Aspergillus flavus. In the presence of the Fusarium spp., there were Review Article Dahunsi et al.; JSRR, Article no. JSRR.2014.14.004 1876 consistent decreases in phosphate and sulphate levels with time. No remarkable decreases in phosphate and sulphate levels were observed with time in the presence of the Lysinibacillus and Absidia species. The study was able to give an insight into the phosphate and sulphate removal ability of the test isolates under the experimental conditions.

Effects of External Carbon Source Concentration on Sulphate Removal by Selected Bacterial and Fungal species

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