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The present work aims at assessing the hazard quotient (HQ) in the groundwater samples collected around Uyo main refuse dumpsite. For calculating the HQ, 17 parameters, namely, temperature, pH, TDS, TSS, BOD, COD, nitrate, Cu, Ni, Pb, Cd, Cl, total phosphate, sulfate, EC, DO and turbidity were considered. The HQ for pH (1.0 – 1.1), temperature (1.2), TDS (0.0), TSS (0.4 – 0.5), BOD (0.5 – 1.0), COD (0.1), nitrate (0.0 – 0.6), Cu (0.7 – 0.8), Ni (0.2), Pb (5 – 16), Cd (3.0 – 10), Cl (0.3 – 0.4), phosphate (1.4 – 1.9), sulfate (0.0), EC (0.1), DO (1.6 – 1.9) and turbidity (0.2). The HQ of temperature, pH, DO, phosphate, Pb, and Cd in water samples were all greater than unity and thus posed a potential health risk for human oral consumption. The present study revealed that groundwater around Uyo village road waste dumpsite poses a health risk to groundwater resource users due to groundwater contamination by the leachate. Monitoring of this site is recommended as well as research by biomedical experts to reveal the rigorous adverse impacts that physio-chemical, and heavy metal contamination of groundwater might induce in humans, particularly among individuals in vulnerable populations. Also, the local authorities should be made aware of such health risks and provide potable water facilities either by treating the water or find alternative sources for drinking.

The process dynamics of anaerobic digestion of municipal solid waste (MSW) in a batch bioreactor for the production of biogas has been analysed. An anaerobic batch digester was designed for the treatment of MSW in Port Harcourt metropolis, Nigeria, while at the same time generate biogas as a useful by-product. In the course of the design, the biochemical behaviour of the MSW in batch processing was investigated and analysed. Mathematical models were developed to describe the behaviour of the waste using material balance analysis. The models were validated by the formulation of a Microsoft Visual Basic Version 6.0 programme to simulate the digestion process for a fractional conversion of 0.2-0.8 and Total solids (TS) concentration of 4-30%. The results were analysed using Microsoft Chart Editor and showed that the fractional conversion has various levels of effect on other process parameters like the mean cell residence time, substrate and microbial concentrations and the volume of biogas/methane produced.

The present investigation discusses the characteristic of leachate generated from municipal solid waste landfill and it adverse impacts on downstream water quality. Landfill leachate was collected from a hole dug 10 m away from the waste dump site and the appearance of the leachate sample looks black. Three downstream water samples were collected at 10 meters intervals each from each other and less than 100 meters from the boundary of the dumpsite. All the samples were examined for temperature, pH, TDS, TSS, BOD, COD, nitrate, ammonia, Cu, Ni, Pb, Cd, Cl, total phosphate, sulfate, EC, DO and turbidity. The aim was to compare physicochemical and heavy metal properties of leachate and downstream water quality with internationally accepted protocols. The Laboratory analysis exhibited prevalence of high value of pH (8.5130.09), temperature(29.00.0), turbidity (14.00.41NTU), DO (0.1670.05 mg/l), COD (68.00.33 mg/l), BOD5 (324.03.00 mg/l), EC (446315.53s/cm), Total phosphate (62.3580.01 mg/l), Pb (0.310.00 mg/l), Cd (0.060.00 mg/l), Ni (0.3550.01 mg/l), and Cu (8.670.04 mg/l) in the leachate sample, which have exceeded their permissible limits. For downstream water samples, pH (7.760.07 to 7.5070.09), temperature (29.00.00) for the three sampling points, DO (3.6670.15 to 3.2330.12 mg/l), total phosphate (8.2250.00 to 7.9350.02 mg/l), Pb (0.4650.01 to 0.0910.00 mg/l), Cd (0.040.00 to 0.0230.00 mg/l), Ni and Cu (0.0430.06 mg/l) and (1.0620.00 mg/l) respectively, also exceeded their respective permissible limit recommended by Nigerian Standard for Drinking Water Quality, World Health Organization in drinking water quality. From this study, there is evidence that there is an increase in risk to surface water that is reported near Uyo village road municipal solid waste dumping site. Therefore, the concerned authority should take appropriate intervention measures to protect surface water. Also, knowledge of leachate quality will be useful in planning and providing remedial measures to protect downstream water quality in the area.