Wastewater Confronting Realities for Sustainable Livelihood in Developing Countries: Case Study Mekelle University, Ethiopia

Abstract

Water is becoming a scarce resource in terms of quantity and quality. Water supply enhancement measures are being taken with less attention given to wastewater management, leading to increased discharge of untreated wastewaters. Wastewater is emerging as an affordable and reliable alternative water supply for urban agriculture, supporting thousands of farmers. Extensive use of untreated wastewater for irrigation will without a doubt lead to accumulation of heavy metals in soils and crops, resulting in overwhelming risks to both public health and the environment. This paper deals with determination of the strength and compositions of the wastewater from a public university in the tropical semiarid region for rainy and dry seasons, based on a number of key parameters including heavy metals. Furthermore, it identified the real advantages of treated water use and issues pertaining to untreated wastewaters use for irrigation purposes. An independent t test showed significant differences in concentrations of all the tested metals, excluding lead, copper, and cadmium during dry and wet seasons. Similarly, differences were significant for electrical conductivity, biological oxygen demand, total nitrogen and total phosphorus. Salinity and concentrations of organics, nutrients, copper, cadmium, iron, manganese and to some extent copper exceeded the allowable thresholds for irrigation water. Lead, zinc, nickel and chromium, on the other hand, were lower than their respective limits. Wastewater used for irrigation purposes is unsafe, and urgent policy interventions on the use of untreated wastewater are required.

Current Status in Quality of Treated Wastewater for Potential Reuse Scheme in Ruai, Nairobi County, Kenya

“…Metals like copper and zinc are essential for enzymatic activity and many biological processes at low concentrations but may become toxic at higher concentrations (Bhatia, et al, 2015). According to USEPA, 2012 as cited in Amare et al, (2017), nickel, cadmium and lead have no known essential functions or role in the body of living organisms but may be toxic even at low concentrations causing a potential health risk through the food chain. Hence, as Amare et al, (2017) further reported, knowledge about these heavy metals' and their concentration in water for use is important, more so because they can become a health risk via consumption of contaminated vegetables, milk, fruit, and drinking water.…”

“…According to USEPA, 2012 as cited in Amare et al, (2017), nickel, cadmium and lead have no known essential functions or role in the body of living organisms but may be toxic even at low concentrations causing a potential health risk through the food chain. Hence, as Amare et al, (2017) further reported, knowledge about these heavy metals' and their concentration in water for use is important, more so because they can become a health risk via consumption of contaminated vegetables, milk, fruit, and drinking water. Fortunately or unfortunately, they are typically not removed from wastewater even after treatment, causing risk of heavy metal contamination of wastewater-irrigated soils and, subsequently, can end up in the food chain (Bhatia, et al, 2015).…”

“…Laboratory analyses for estimating the concentration of the metals in the TWW were carried out using atomic absorption spectrometer (AAS) using the respective hallow cathode lamp (Hack 1992;Eaton et al 2005;Koffi et al 2014;Amare et al 2017;El Moussaoui et al, 2017). To determine the instrument signal response to changes in concentration, calibration was done using working standard solutions of known and increasing concentrations for each metal (analyte element) in the study as stipulated in Hack (1992) and Amare et al, (2017). By measuring the signals of the working standards, the AAS constructed a suitable calibration curve of response/absorbance versus concentration.…”

“…Biochemical oxygen demand (BOD) was determined using a 5-day digital BOD test at 20 °C as described in Eaton et al (2005) and Amare et al, (2017). For Chemical oxygen demand (COD) determination, the sample was mixed with 1.5 ml potassium dichromate solution and 3.5ml sulphuric acid (catalyst) in a Rota mixer digester for two hours.…”

Low Cost and Eco-Friendly Removal of Toxic Heavy Metal from Industrial Wastewater

“…(Rai 2012;Tantawy et al, 2015;Thirumdas et al 2018;Saha and Rahman 2018). Thus water security is amongst the top five global crises regarding development impacts (Amare et al 2017). In addition, water bodies' contamination by HMs through discharging industrial wastewater is a worldwide environmental issue that needs to be properly addressed.…”