Abstract
Pollution resulting from increased human activities is threatening Lake Victoria, its effects are characterized by eutrophication, high turbidity, pH, iron(II) concentration and chemical oxygen demand (COD). In this study we have investigated the effect of Fe-montmorillonite clay from Chelel on turbidity, pH, concentration of iron, total suspended soils, total nutrients and COD of water sampled from Murchison bay watershed of Nakivubo channel south of Kampala. Varying amounts of clay powder was vigorously stirred with water samples for 5 minutes, filtered using Whitman paper at ambient temperatures. The optimum concentration of clay of 0.4gl-1 was found to produce 73.5+ 2% fall in COD indicating elimination of microbes and organic waste. The pH of water became 6.3+ 0.2 showing that impurities had been bound to clay. The turbidity of filtrate dropped to 15.7+ 0.3NTUshowing that clarity of water was improved by adsorption of suspended solids to clay minerals. The concentration of iron(II) fell from 3.7 + 0.3 to 2.5+ 0.2mgl-1 indicating fairly high extent of heavy metal removal from Murchison bay (MB) waters. The TSS and nutrients in MB water also decreased greatly when clay was stirred with water at ambient temperatures. The available data can be relied on to recommend use of this clay in treatment of waste water and/or sewage from Kampala. Further studies on combined use of clays with alums, zeolites and/or lime need to be carried out.
Highlights
Water is the most precious resource on Earth
In this study we investigated the clarification of water from Murchison bay (MB) using Fe-montmorillonite clay from Chelel to alleviate use of alums, chlorine and/or fluorine poisons because the use of clays is becoming popular as adsorbent and ion-exchange for water and wastewater treatment in removing heavy metals, organic and inorganic pollutants (Abdallah and Gaber, 2004)
The clay was mined from a valley yet diagenesis took place uphill, the possibility of in situ alteration was unlikely as the clays were eroded
Summary
For the vast quantity of life to exist, access to fresh water is important. The water constitutes more than 70% of the Earth surface, only 2.5% of it is fresh. Protecting fresh water reserves around the world is very important. Sources of fresh water are contaminated to become undrinkable through pollution but the effects can be reversed through wastewater treatment (Syafalni et al 2013). Surface water pollution is the most visible form of water pollution where in plastics and garbage can be seen floating in lakes, rivers and oceans as was reported about river Lubigi (Musingizi et al 2013). Surface water pollution may include industrial accidents like oil spills and wastewater. Ground water pollution happens beneath the soil and is caused by highly toxic chemicals like pesticides or chemical spills. Depletion of oxygen in water is caused by microorganisms present in polluted water that consume biodegradable wastes (Syafalni et al 2013)
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