Public water supply in Lagos State, Nigeria: Review of importance and challenges, status and concerns and pragmatic solutions

The challenges faced in public water supply in most cities and developing countries are increasing population size, poor operational efficiency of existing waterworks, leakages, low reticulation coverage and poor cost-recovery. Our study revealed variation in the public water-supply-demand gap estimates under low, middle and high population growth rate scenarios. Under a largely urbanized evolution of the LGAs, Lagos State faces an imminent critical water shortage if pragmatic steps are not taken to bridge the public water supply-demand gap. Pragmatic solutions recommended include strategic planning and implementation of new waterworks, improved operational efficiency of existing waterworks, improved reticulation and appropriate cost-recovery

SDA and laterite applications in concrete: Prospects and effects of elevated temperature

This research supports green eco-friendly construction through utilization of laterite and sawdust ash as fine aggregate and supplementary cementitious material in concrete. Critical literature review revealed that at fine aggregate replacement by laterite ≤50, 50–75 and 100%, mix ratios 1:2:4:0.56, 1:1.5:3:0.65 and 2:3:6:0.65 respectively are preferable for structural applications. Higher compressive strength losses of 32.81, 28.23 and 32.59% were recorded at elevated temperatures of 200, 400 and 600°C for SDA-modified laterized concrete while lower strength losses of 8.58, 7.91 and 3.74% were recorded for conventional laterized concrete. However, strength gain of 15.9% was recorded at 25°C ambient temperature for SDA-modified laterized concrete. Based on elevated temperature results, 10% SDA-modified laterized concrete at 45% optimum laterite content can only be used for production of load-bearing bricks and blocks and other non-structural applications. Further research efforts on green construction are required

Assessment of rainfall variability, rainwater harvesting potential and storage requirements in Odeda Local Government Area of Ogun State in South-western Nigeria

Rainfall variability with periodicity of 5–6 years has been demonstrated for our study area and may be attributed to tropical and extra-tropical factors which operate during different months, seasons and years. Rainfall variability in terms of coefficient of variation ranges from 24 to 39% and 26 to 41% for the seasons and months. The mean increase of 1.63 mm/year and 1.37 mm/year experienced in the dry season months (November–April) and the wet season months (May–October), respectively, is insignificant from a water management perspective. Hoeffding’s D statistics revealed prevalence of non-monotonic trend in all the months and seasons. Recommended minimum and maximum storage capacity requirements for a six-member household to maximize rainwater harvesting are 1 and 6 m3, respectively. The rainwater harvesting potential for the area of study ranges between 18.16 and 27.45 m3 and 15.23 and 30.40 m3 based on the maximum error estimate and coefficient of variation methods. Domestic rainwater harvesting has the potential to meet 27.51–54.91% of non-potable household water demand as well as 78.34–156.38% of household potable water demand for a six-member household. It is highly encouraged as a supplementary water source especially in rural and peri-urban areas to reduce their vulnerability to acute shortage of water infrastructure

Recycling of polyethylene terephthalate (PET) plastic bottle wastes in bituminous asphaltic concrete

This research sheds light on the concept of eco-friendly road construction which comprises eco-design, eco-extraction, eco-manufacturing, eco-construction, eco-rehabilitation, eco-maintenance, eco-demolition, and socioeconomic empowerment. It also revealed the challenges being faced in its adoption and the benefits derivable from its application. Furthermore, the effects of recycling PET plastic bottle wastes produced in North Central Nigeria in bituminous asphaltic concrete (BAC) used in flexible pavement construction were also evaluated. The mix design consists of 60/70 penetration-grade asphaltic concrete (5%), 68% coarse aggregate, 6% fine aggregate, and 21% filler using the dry process at 170°C. The optimum bitumen content (OBC) for conventional BAC was obtained as 4% by weight of total aggregates and filler. Polymer-coated aggregate (PCA)-modified BAC seems preferable because it has the potential to utilize more plastic wastes with a higher optimum plastic content (OPC) of 16.7% by weight of total aggregates and filler compared to that of 9% by weight of OBC achieved by PMB-BAC. For both PMB- and PCA-modified BAC, an increase in air void, void in mineral aggregate, and Marshall stability were observed. Eco-friendly road construction which recycles PET wastes should be encouraged by government considering its potential environmental and economic benefits

Evaluation of groundwater quality in a rural community in North Central of Nigeria

Evaluation of water quality of nine boreholes and three open hand-dug wells in a rural community in North Central Nigeria revealed relative abundance of cations Na > k > Ca >Mg> Zn > Pb and anions Cl− > PO4 2 − > SO4 2 − > NO3− in the boreholes and cations Ca>Na>K>Mg>Pb and anions NO3− > PO4 2 − > SO4 2 − > Cl− in the wells. The major contaminants exceeding SON and WHO permissible limits were NO3−, Mg, TH, pH and Mg, Pb, TH, pH and DO in the wells and boreholes, respectively. They are attributable to anthropogenic sources such as domestic waste water and poor waste disposal and natural sources such as mineral dissolution from clayey aquifer which made the acidic groundwater unsuitable for consumption unless they are appropriately treated. Correlation studies revealed existence of three major mineral groups in the aquifer Ca-Fe group, Na-Mg group, Zn-K group, as well as a minor group Pb-group, and they determine the chemical composition of the groundwater and the ionic exchange between the groundwater and mineral-bearing clayey aquifer. In order to curb microbial contamination by Enterobacter aerogenes and Escherichia coli, it is recommended that proper latrines and drainages be provided while domesticated animals should be restricted from boreholes and well. Further, treatment with water guard and pur purifier is recommended