This study considered the estimation of the time of concentration (TC) using 30 different watersheds in Anambra State, Nigeria. The study assessed the performance of some existing models for the estimation of time of concentration in the study area. Data for this research were collected from watersheds located at Awka-South Local Government in Anambra State. A measured time of concentration values was also obtained by using a tracer at the watershed divide and the time it took the tracer to get the outlet of the watershed was recorded. This was carried out on all the 30 watersheds at the same time. The length, slope and area of the 30 watersheds were also measured. Thereafter, the time of concentration was estimated using the 30 existing models. The extent of linear association between the observed and estimated time of concentration for the different models was determined. The outcome of the study revealed that the Ventura model (Tc12) developed in Italy recorded the highest correlation coefficient with a measure of 0.681, followed by DNOS model (Tc14) with a coefficient measure of 0.661 while the least performing model was Picking model (Tc13) with -0.423 correlation measure. There was also an obvious difference in the values of the time of concentration calculated using the different models. Therefore there is always a need to verify any model to be used for estimating the time of concentration in other to have a more robust design.

There are two basic reasons for the treatment of sewage, reuse and proper control of wastewater and water pollution, and safeguarding the public and environmental health by protecting water supplies and preventing the spread of waterborne diseases. Proper design, and construction together with good operation and maintenance are important authorities. In the present study, a comprehensive design was developed for the units of Inlet chambers for sewage treatment plants, to produce effluents which are satisfying the safe disposal or reuse prescribed by the regulatory, Screen chamber, Grit Removal Unit, sedimentation Tank, Clari-Floculator, Aeration Tank, Sludge Drying Beds, etc. as they are commonly used in the field of wastewater treatment. The plant which is designed to treat 44.625MLD of sewage generated by the inhabitants of Agulu will use as many sustainable and energy-efficient concepts as possible, while still keeping construction and maintenance costs low. The overarching goal of the project which is designed to serve for the next 3 decades is to prevent the contamination of surface water like the Agulu lake and also groundwater, while also providing clean effluent for disposal that can be further treated for consumption.

This study investigates the impact of groundwater pollution in Oyigbo Local Government Area, Nigeria, and the consequences of solid wastes, quality, and its control. The study was inspired by the uncontrolled way that both home and industrial wastes are dumped on the ground, in rivers, burried, burned, and dumped in trash heaps. Papers and polyethene, tin and metals, ashes and dust, texture and rags, aluminum and other minerals are among the primary solid wastes produced in Oyigbo. These wastes form leachates and gases when they degrade and are washed by percolating and infiltrating rain water into the groundwater, according to an examination of the physical, chemical, and biological properties of raw water at ten distinct places in Oyigbo close to disposal grounds. However, while a small number of the water characteristics evaluated did not meet W.H.O. criteria, the majority did. Despite this, recommendations are given to address the issues, including promoting raw water analysis, awareness campaigns, increased groundwater investigation in Oyigbo, and adherence to the resource management principle. From the results obtained, it was discovered that the mean concentration values of TDS, pH, BOD and COD are 89.24mg/l, 7.62mg/l, 13.87mg/l and 14.58 for leachate samples. Also the mean concentration values for Mn, Cl, Mg in groundwater samples are 62.34mg/l, 22.74mg/l and 2.60mg/l and for well water samples and 57.35mg/l, 28.30mg/l and 1.25mg/l respectively. The characteristics of the domestic well water samples showed a mean concentration of biochemical Oxygen Demand (BOD = 16.26 mg/l), Chemical Oxygen Demand (COD = 18.67 mg/l), Dissolved Oxygen (DO = 4.84 mg/l) and temperature (29.66ᵒC). Also, the characteristics of the groundwater samples showed a mean concentration of biochemical Oxygen Demand (BOD = 13.67 mg/l), Chemical Oxygen Demand (COD = 16.11 mg/l), Dissolved Oxygen (DO = 4.03 mg/l) and temperature (27.16ᵒC). This result shows that there are high level of BOD,COD and DO in Domestic well water than that of groundwater in that location(site).

The study assessed the impact of effluent discharges on the quality of Otamiri River in Imo state, Nigeria. Six water samples were collected at discharge points where the industries discharge their effluents and abattoir. Samples that were collected upstream and downstream were analyzed in the field and in the lab using standard procedures.  The source of pollution is attributable to industrial and abattoir activities whose effluent discharges impact the quality of Otamiri River. Therefore, without any treatments, the River cannot be used for any residential purposes in its current condition. It is advised that the river be periodically monitored and that cost-effective manufacturing technology, such as on-site waste separation and reduction, effluent recycling techniques, be introduced.

Hazardous waste products are drugs that are now not highly required and thus have no actual or customer value at an allocated time or location. Countless raw materials used or manufactured in metabolic pathways must have hazardous qualities. The important hazardous waste publications usually involve heavy industry, physician, and residential squanders, and actually happen in stable, solvent, or vapor. These waste products seem to be consolidated and/or just have inherent or inherent physiochemical individuality of cytotoxic activity, combustible material, standard test, and reactions. Managing hazardous wastes is always of incredible symbolic importance to people, socio, environmental, and economic health conditions. Hazardous wastewater reuse process in the maternity ward may not be in concurrence with the top global methodologies. Many harmful byproducts are tossed carelessly, which encompasses hazop to the climate and confronted public health troubles. This investigation will inform the general public, vested interests in environment protection, student academic, and governmental policy producers on the concerns of waste disposal focusing on health facilities with a view to assessing best practices to fight the scourge linked to poor hazardous waste management. But progress remains a challenging task, such there still is a lack of available effective steps to still be chosen to take towards workable practices to the issues.