Characterization and projection of dry season municipal solid waste for energy production in Ilorin metropolis, Nigeria.

This research investigates the quantity of municipal solid waste produced during the dry season, and its characterization at Eyenkorin dumpsite of Ilorin metropolis, along the Lagos-Ilorin express way. The physicochemical and thermal compositions of the combustible fractions of municipal solid waste were analysed, to ascertain the available calorific value. In this research, the quantity (tonnes) of waste generated, the rate of generation (kg per capita per day), its sustainability and the likely energy and power potentials in the dry season, were essentially predicted. The population responsible for municipal solid waste generation during this study was 1,120,834 people. During the characterization study from November 2018 to February 2019, it was established that 203,831 tonnes of municipal solid waste was produced during the four months of the dry season, at the rate of 1.12 kg per capita per day. It was found that 280 tonnes/day of municipal solid waste with low heating value of 19 MJ kg-1, would generate 1478 MWh of heat energy and 18 MW of electrical energy potentials discretely, and grid of 13 kW.

Crop performance and soil fertility improvement using organic fertilizer produced from valorization of Carica papaya fruit peel.

In recent times, research attention is focusing on harnessing agricultural wastes for the production of value-added products. In this study, the valorization of Carica papaya (Pawpaw) fruit peels was evaluated for the production of quality organic fertilizer via anaerobic digestion (AD) while the effects of the fertilizer on maize crop were also assessed. Pawpaw peel was first pretreated by thermo-alkaline methods before AD and analyses were carried out using standard methods. The resulting digestate was rich in nutrients and was dewatered to form solid organic fertilizer rich in microbes and soil nutrients. When applied to maize plants, organic fertilizer showed a better effect on plant traits than NPK 15-15-15 fertilizer and without fertilizer application. These were more pronounced at mid to high organic fertilizer applications (30-to-60-kg nitrogen/hectare (kg N/ha)) rate. Comparison between the values obtained from the field experiments reveals that the organic fertilizer showed better performance in all parameters such as the number of leaves, leaf area, plant height, stem girth, total shoot, and root biomass, and length of the root. However, the chemical fertilizer outperformed all the organic fertilizer applied rates in the average highest size of the corn ear by 1.4%. After harvesting, nutrient elements were found to have bioaccumulated in plant organs (leaves, stem, and root) with the highest values being 29.7 mg/L for nitrogen in the leaf and this value was reported from the experiment with 50 kg N/ha. For phosphorus and potassium, the highest concentrations of 7.05 and 8.4 mg/L were recorded in the plant' stem of the experiment with 50 kg N/ha. All the treated soils recorded an increase in values of all nutrient elements over the control with the highest values recorded in the experiment with 60 kg N/ha. In soil with 60 kg N/ha, the nitrogen, phosphorus, and potassium increased by 28, 40, and 22% respectively over the chemical fertilizer applied experiment while different levels of increases were also recorded for all other macro and microelements in all the experiments. Thus, agricultural practices by using anaerobic digestates as organic fertilizers is a sustainable method to overcome the dependence on inorganic fertilizers high rate.

Electricity generation from food wastes and spent animal beddings with nutrients recirculation in catalytic fuel cell.

A biochemical system was used for electricity generation from food waste (FW) and spent animal beddings (SAB). The wastes were blended and fermented anaerobically to produce fermentation liquids used as fuels for running a catalytic fuel cell. The fermentation liquids were analyzed for their components. The results show the organic contents i.e. volatile solids of both FW and SAB to be 23.4 and 20.9 g/L while the carbon contents were 6.5 and 6.1 g/L respectively. The media were however very rich in volatile fatty acids (VFAs). When used, the fermentation liquids from FW and SAB generated mean open-circuit voltages of 0.64 and 0.53 V and mean maximum power densities (Pmean) of 1.6 and 1.3 mW/cm2 respectively. The fuel cell showed very high efficiency in the conversion of all VFAs especially butyric acid with the highest been 97% for FW and 96% for SAB.

Co-digestion of Theobroma cacao (Cocoa) pod husk and poultry manure for energy generation: Effects of pretreatment methods.

In this study, biogas was produced from the anaerobic co-digestion of Cocoa pod husk (CPH) and poultry manure. Pretreatment of the CPH was carried out using sulfuric acid and hydrogen peroxide. The physicochemical, elemental and structural analyses were carried out on the CPH before and after pretreatment. The microbial composition of the fermenting materials were also determined using standard method while the Fourier Transform Infra-red (FTIR) spectroscopy was used to identify the structural changes that took place after pretreatments. Use of alkaline hydrogen peroxide caused high solubilization of the lignin component of the CPH and reduced up to 81% of lignin i.e. initial value of 21.7% m.m-1 to final value of 4.2% m.m-1. Similarly, the alkali reduced the hemicellulose content of the CPH from 27.0% m.m-1 to 8.5% m.m-1. Overall, there was 68% increase in biogas volume from the alkaline pretreated CPH.

Mechanical pretreatment of lignocelluloses for enhanced biogas production: Methane yield prediction from biomass structural components.

In this study, mechanical pretreatment was applied to six different lignocelluloses in two different treatment phases and the prediction of their methane yield was done from biomass chemical composition. Physicochemical, proximate and microbial analyses were carried out on both pretreated and untreated biomass using standard methods. Mechanical pretreatments caused the breakdown of structural materials in all the used biomass which was characterized by reduction of the lagging time during anaerobic digestion and the subsequent increase in methane yield up to 22%. The different loading rate of biomass had no effect on the overall methane yield increase. Both single and multiple linear regressions models were used in order to correlate the chemical composition of the biomass with their methane potentials and a fairly high correlation (R2 = 0.63) was obtained. The study also showed that the pretreatments are economically feasible. Therefore, its further application to other biomass is encouraged.

Data on energy and economic evaluation and microbial assessment of anaerobic co-digestion of fruit rind of Telfairia occidentalis (Fluted pumpkin) and poultry manure.

The data described in this article was obtained in an experiment designed for the generation of biogas from the anaerobic co-digestion of Telfairia occidentalis (Fluted pumpkin) fruit rind and poultry manure both of which currently constitute an environmental nuisance in the localities where they are found. The data presented in this article is on the use of combined heat and power (CHP) system to assess the energy and economic feasibility of applying thermo-alkali pretreatment procedures to one of the substrates (Fluted pumpkin) prior to anaerobic digestion. Also, the microbial characterization and succession pattern of important microbes during the anaerobic digestion process was evaluated and the data reported in this paper.

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.

Synergy of Siam weed (Chromolaena odorata) and poultry manure for energy generation: Effects of pretreatment methods, modeling and process optimization.

The co-digestion of Chromolaena odorata with poultry manure was evaluated in this study. Two samples of the weed: (A: which was pre-treated with mechanical, chemical and thermal methods) and (B: which was pretreated using mechanical and chemical methods only) were separately digested with poultry manure. Biogas generation started from the 2nd to 4th and 4th to 7th day for samples 'A' and 'B' respectively. The most desired actual biogas yield from samples 'A' and 'B' were 3884.20 and 2544.70 (10-4m3/kg VS) respectively and the gas composition was 68±2% Methane and 20±2% Carbon dioxide for sample A while it was 62±3% Methane and 22±2% Carbon dioxide for sample B. In all, there was a 38.06% increase in gas generation in 'A' over 'B'. The coefficient of determination (R2) for the Response Surface Methodology (RSM) model (0.9009) was high suggesting high accuracy in the modeling and prediction. The worldwide usage of C. odorata is encouraged.

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.

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.

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.

Preliminary study on hazards and critical control points of kokoro, a Nigerian indigenous fermented maize snack.

The microbial and proximate composition of an indigenous snack from fermented maize was investigated. Critical control points of milling the raw materials, fermentation pH, processing temperature and time intervals during holdings in processing and storage were evaluated with a view to optimizing the product. The mean total aerobic plate count (TAPC) log10 values for samples of the finished products range from 2.07 ± 0.50 to 4.36 ± 0.10 cfu/g. Mean fungi count log10 was 2.00 ± 0.00 to 3.50 ± 0.50 while mean coliform count 1.04 ± 0.10 log10 cfu/g was detected in one of the sales outlets investigated. Bacterial and fungal species were isolated belonging to the genera Aspergillus, Rhizopus, Penicillium, Fusarium, Cephalosporium, Alternaria, Bacillus, Klebsiella, Staphylococcus, Lactobacillus, Pseudomonas, Proteus and Enterobacter. The moisture content of the samples ranged from 3.41 to 6.75%; fat content was 19.68 to 32.59%; fiber content was 1.84 to 2.78% while protein ranged from 6.76 to 9.23%. The ash and carbohydrate contents ranged from 1.97 to 2.31% and 49.21 to 61.96%, respectively. Based on the specifications by International Commission for Microbiological Specification for Foods (ICMSF), the TAPC counts of the finished products remained at low levels. However, presence of coliforms could prejudice the hygienic quality of these types of products hence, the need for quality control.

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.