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Tannery wastewater is often characterized by their complexities in terms of contaminants and require specialized treatment technologies. Hence, the objective of this paper is to explore the performance evaluation of a laboratory-scale horizontal subsurface flow constructed wetland (HSSFCW) in the treatment of tannery wastewater in Kaduna, Nigeria using appropriate standard techniques. Out of the tree replica systems, two were respectively vegetated with Phragmites australis and Polygonum salicifolium + Ipomoea carnea, while the last was left un-vegetated and used to treat tannery effluent. Characteristics such as Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Nitrates (NO-3), phosphates (PO43-), suspended solids (TSS) and chromium (Cr) analyzed using standard methods were used as indicators of the treatment efficiency under a 6-day Hydraulic Retention Time. The results showed that the system vegetated with Phragmites australis had the best performance in the removal of BOD, COD, NO-3, PO43- and Cr (97.9%, 94.2%, 54.4%, 44.1% and 98.4% respectively). The system vegetated with Polygonum salicifolium + Ipomoea carnea on the other hand had the best performance for SS removal (92.6%) while the system vegetated with Phragmites australis had a SS removal efficiency of 92.3%. The performance indices for unvegetated cell, Phragmites australis vegetated cell and Polygonum salicifolium + Ipomoea carnea vegetated cell were respectively, 4, 9 and 8 which shows that the cell vegetated with Phragmites australis had the best performance in the treatment of tannery wastewater. It also showed that the performance of the cell vegetated with Polygonum salicifolium + Ipomoea carnea was also comparable with that of Phragmites australis. This study demonstrated that the HSSFCW vegetated with both Phragmites australis and Polygonum salicifolium + Ipomoea carnea can effectively treat tannery wastewater. There is however a need to investigate the efficiency of the system over a longer period with consideration of microbial characteristics.

The characteristics of Soil is one of the major factors that affect flooding. This study therefore was carried out to assess the infiltration rates and index properties of soil within a flood-prone community of Oforachi in Kogi State, Nigeria using appropriate standard methods. Data obtained showed that the average soil infiltration rate ranges from 1.89 – 3.24 cm/hr and the maximum infiltration rate range between 6.00 – 9.00 cm/hr, while the soil antecedent moisture content was between 15.00 – 42.48 %. Soil infiltration properties classification based on hydraulic conductivity and sieve analysis show that soils within the study area combine silt and clay characteristics which has strong relationship with the persistent flood experienced in the area.

Landfills and solid waste disposal facilities have historically been the most common point sources of pollution with the potential to release contamination leachate plumes into the environment. Waste disposal is one of the biggest problems that the world is facing. In man’s everyday life, he produces waste materials which, if not properly managed, can affect health and environment. The seepage of landfill leachate into groundwater tables and aquifer systems significantly creates a possible danger and threat to human health and environment at large and remains a subject of concern in Nigeria and other parts of the world. This paper provides a review of existing approaches to leachate treatment in Nigeria and current practices across the globe, depicts the impact on environmental implications, documented previous findings, challenges and mitigation measures, and future perspectives of landfill leachate management in Nigeria, and compares with global practice of leachate management. In Nigeria, there are only a few standard techniques of landfill leachate treatment. This resulted in severe environmental impacts that threaten human life, especially in the north-eastern part of the country. Vector-borne and water-related illnesses such as cholera, Dengue, Diarrhoea, Trachoma, typhoid, malaria etc, have become a major source of concern resulting from the leaching effect from landfills. Advanced treatment methods, including membrane filtration, trickling filters, and Batch and Sequencing-Batch Reactors (SBR) are used in some of the cities and private organizations in Nigeria. Most researchers in Nigeria have stressed the necessity to utilise efficient, cost-effective technology in landfill wastewater treatment. Despite this, landfill leachate has continued to have severe effects in Nigeria and the situation seems to be escalating, requiring further study.

Appropriate treatment of wastewater before disposal into the environment or reuse is very important in the quest to protect the environment and safeguard public health. This paper investigated the performance evaluation of a waste stabilization pond (WSP) for treatment of wastewater from a tertiary institution campus located in Jos North Local Government Area of Plateau State in North Central Nigeria. The waste stabilization pond of the tertiary institution campus was designed for a wastewater flow rate of 12,945 m3/day. In order to evaluate the performance of the WSP, a model was developed following the Froude’s number dimensional analysis technique. The model was evaulated based on a wastewater flow of 0.4 m3/day. The final effluent from the maturation pond had 80 mg/L BOD, 195 mg/L COD, 75 CFU/100ml Total Coliforms, 610 mg/L Total solids, 19 mg/L Total Nitrogen, 210 mg/L Chloride, 28 mg/L Phosphate, 1.3 mg/L Ammonia and 7.0 pH. The WSP was able to achieve an overall efficiency of 77.78% reducing all quality parameters to recommended limited with exception of total nitrogen and phosphate. The implementation of this design will go along way to aid the treatment of wastewater from the campus of the university.

The morphometric characteristics of a river basin are very important factors in watershed hydrology. The morphometric analysis of the Ofu River sub-basin was carried out in this study to assess its morphologic and hydrological characteristics as well as its flood potentials based on the morphological characteristics. The study was carried out using remotely sensed spatial data analysed using Geographical Information Systems (GIS). The morphometric parameters analysed were the areal, linear, and relief aspects of the sub-basin. The results showed that Ofu river sub-basin covers a total area of 1604.56 km2 and a perimeter of 556.98 km covering parts of Kogi and Enugu States in Nigeria. The sub-basin has 3rd order river network based on the Strahler’sclassification with a dendritic drainage pattern and moderate drainage texture. The values of bifurcation ratio, drainage density, circularity ratio, elongation ratio, form factor, stream frequency and drainage intensity indicate that the sub-basin is elongated and would produce a flatter peak of direct runoff for a longer duration implying that the sub-basin is morphometrically less susceptible to flood and that any flood flow that may emanate from it would be easy to manage.

The drainage basin surrounding River Kaduna within the middle stretch is known to have numerous land uses and land covers. Several researchers have investigated the water quality of the river with respect to season and surrounding geology. However, none or little on the water quality of the river have been investigated with respect to land use and land cover (LULC). Hence, this paper examined the water quality of the middle stretch of the river in relation to the different land uses and land covers present using statistical techniques. This was achieved by monthly analyzing 10 physicochemical parameters from water samples collected in 15 sampling stations for a period of 12 calendar months using standard methods. The physicochemical parameters considered are; turbidity, total dissolved solids, pH, chloride ion and electrical conductivity. Others include dissolved oxygen, 5-days biochemical oxygen demand, chemical oxygen demand, total nitrogen and total phosphorus. The different LULC of the watershed obtained via ArcGIS 10.5 were agricultural, vegetation, built-up, industrial, water body and bare surface. Spearman’s correlation analysis between laboratory results and the different LULCs determined via SPSS version 20 revealed that Built-up, industrial, and agricultural land uses contributes significantly to the impairment of River Kaduna water quality as the correlation coefficients between these LULCs and water quality deterioration ranged from 0.0281 to 0.6901. Nevertheless, there was a significant negative correlation (-0.1482 to -0.5490) between vegetation (forest coverage) and water quality deterioration, suggesting that forest cover can mitigate the deterioration of water quality to a certain degree.

Flood risk assessment of Ofu River Catchment in Nigeria was carried out by integration of thematic maps in ArcGIS 10.2.2. Analytic Hierarchy Process (AHP) was applied in the decision making and ranking of flood causative factors before their integration for development of hazard map in ArcGIS. The social and physical vulnerability of the catchment were considered in the development of the vulnerability map. The flood risk map was developed as a product of the hazard and vulnerability map. The results showed that the land areas within the Very High and High Risk zones were respectively 163.07 km2 and 392.63 km2 with Igalamela/Odolu Local Government Area (LGA) accounting for about 62% and 31% respectively. A total of 19, 034 and 47,652 persons are respectively at very high and high risk of flood within the catchment. Oforachi community in Igalamela/Odolu LGA and Ejule Ojebe Community in Ibaji LGA both in Kogi State are respectively at Very High and High Risk of Ofu River flood. High Impacts were recorded by about 35% and 52% of Oforachi Community during the 1995 and 2000 historical flood events. A watershed management plan is therefore required to prevent the serious damage experienced in previous flood events.

The stage-discharge rating curve is widely used in the research for analysis of flow regime and design of hydraulic structure and river channel where the measurement of discharge is difficult especially in developing countries like Nigeria. This study sought to develop a stage-discharge relationship for Ofu River in Nigeria where water resources project planning has been limited by the unavailable of stream flow data. Discharge Measurement was carried out using Valeport Current meter while stage was measured using staff gauge at Oforachi Bridge hydrometric station from February, 2016 to January, 2017. The Stage and discharge results were used to determine the curve coefficient via regression analysis and finally the rating curve equation for the river at this station. The Oforachi Bridge serves as the permanent control, thus the curve is reliable.