Impact of Discharged Wastewater Final Effluent on the Physicochemical Qualities of a Receiving Watershed in a Suburban Community of the Eastern Cape Province

Abstract

Failures of sewage treatment systems, both within and outside South Africa, are most commonly ascribed to inadequate facilities and other factors resulting in the production of poor quality effluents with attendant negative consequences on the receiving watershed. The impact of the final effluent of a wastewater treatment facility in a suburban community of the Eastern Cape Province of South Africa on the physicochemical qualities of the receiving watershed was assessed between August 2007 and July 2008. Water quality parameters were analyzed according to the South African Department of Water Affairs and Forestry standards. The effluent quality was acceptable with respect to the pH (6.9–7.8), temperature (13.8–22.0°C), dissolved oxygen (DO) (4.9–7.8 mg/L), salinity (0.12–0.17 psu), total dissolved solids (TDS) (119–162 mg/L) and nitrite concentration (0.1–0.4 mg/L). The other physicochemical parameters that did not comply with regulated standards include the following: phosphate (0.1–4.0 mg/L), chemical oxygen demand (COD) (5–211 mg/L), electrical conductivity (EC) (237–325 μS/cm), and turbidity (7.7–62.7 NTU). The results suggest that eutrophication is intensified in the vicinity of the effluent discharge points, where phosphate and nitrate were found in high concentrations. The discharged final effluents had detrimental effects on the receiving body of water, thus suggesting the need for regular and consistent intervention by appropriate monitoring and compliance agencies to ensure adherence to acceptable standards for discharged effluents.

Water Quality Management Based on Division of Dry and Wet Seasons in Pearl River Delta, China

“…Significant negative correlations were identified between AT and DO, and WT and DO in dry season. Osode and Okoh [51] provided a similar result in the study about the physicochemical qualities of a receiving watershed for wastewater in Eastern Cape Province, South Africa. This is because temperature changes greatly in dry season and warmer water is more easily saturated with oxygen [46,52,53] and the production speed of oxygen is less than the consumption speed of oxygen with increasing temperature and decreasing discharge [12].…”

Physicochemical Properties of Wastewater in Three Typical South African Sewage Works

“…The acceptable standard for drink purposes is 6 mg/L and for aquatic organisms is 4-5 mg/L. DO in concentration in unpolluted water normally ranges from 8-10 mg/L [18]. Low DO in water disturbs the existence of fish by increasing their susceptibility to disease, migration, and reproductive behaviour, hindering swimming capacity, fluctuating feed, and leading to death of aquatic life [28].…”

“…Phosphate generally is a limiting factor in aquatic environments and leads to various undesirable ecological challenges in the water system [41][42]. High levels of phosphate and nitrates enhance the growth of vegetation in water bodies and increase oxygen demand [18].…”

“…This disqualifies both the receiving water and the discharged effluent for domestic use [43]. Studies have shown that too much turbidity in water can lead to interference with some treatment steps at some stages, such as coagulation and separation solids of the water treatment techniques, which may increase treatment cost, and when extremely turbid water is chlorinated, there is a possibility for a rise in trihalomethane (THM) precursor formation [18].…”

“…The concentration levels of nitrate, nitrite, phosphate, sulphate, chloride, and ammonium (Merck Pty Ltd.) were analyzed using the spectroquant Pharo 100 [17], while Alkalinity of the water samples was determined through titration. The free chlorine was quantified using the DPD method [18]. Physicochemical Properties of Wastewater...…”