A Review Of Selected Natural Coagulants In Water And Wastewater Treatment

The United Nations’ Sustainable Development Goal 6 (SDG 6) aims to ensure the availability and management of water and sanitation for all, including an end to open defecation, by 2030.1 Lack of access to clean water and proper sanitation affect all aspects of human life across the globe, having the largest negative effects on least developed countries and marginalized communities. About 36% of the global population live in water-scarce regions, with more than two billion people having no other choice but to consume contaminated water. Water pollution is the greatest culprit in ecosystem destruction, leading to biodiversity loss with often irreversible consequences. Water scarcity is expected to displace 700 million people by 2030, while desertification will put the livelihood of one billion people living in 100 countries across the world at risk by 2050.2 Despite these risks, our society has very few incentives to consume less water, maintain water quality, or allocate funding and resources to ecosystems or social objectives.3 In order to fulfill the objectives of the SDG 6, the High Level Panel on Water called for a “fundamental shift in the way the world looks at and manages water”, noting that a 40% shortfall in water availability by 2030 could be expected if no action is taken.4 An urgent need to develop innovative approaches to solve global water scarcity and quality issues has arisen, as traditional financing solutions and technologies have proven to be insufficient in addressing these challenges.

Introduction Every year in South Africa an estimated R500m is spent on chemicals used in the treatment of drinking and waste water. Most of this money is allocated on the basis of tenders issued and contracts awarded. The evaluation of tenders is generally undertaken by a team of people from various disciplines within the awarding organization and the decisions they make can have a significant effect on the quality of water or waste that is produced and also on the finances of the organization for which they work. It is obvious therefore that these decisions – which chemicals to use, how much to use, how much should be paid, who is the most professional supplier – are important ones and ones that should be taken whilst in possession of the most factual and impartial information. This guide aims to provide those decision-makers, and other users of water treatment chemicals, with specific and useful information about water treatment chemicals. It is a chemistry text book aimed specifically at those people who have to make informed decisions but who have not had a formal education in chemistry or whose chemistry education has not been specific in detail relevant to water treatment chemicals. It does not, however, aim to be a comprehensive chemistry textbook and chemicals not used in water treatment are not discussed; nor are properties that are irrelevant to the water treatment application of the chemical. The guide is designed to serve as a reference book with each chapter being self contained and specific. It will be easily understood by those readers that do not have a formal chemistry education and hopefully will provide some useful additional insight and information to those that The guide is divided into ten chapters and includes an appendix at the end that contains various useful equations. The contents of each chapter are listed below.

Over the last few decades adsorption has gained paramount importance in industry and environmental protection. Adsorption processes are widely applied for separation and purification because of the high reliability, energy efficiency, design flexibility, technological maturity and the ability to regenerate the exhausted adsorbent. One method of important extending the adsorption treatment processes is biofiltration. The biological filter relies on the activities of the community of micro-organisms that become attached onto the filter media. Microbes oxidize organic matters in water to produce energy and therefore available nutrients sources in feed water are essential for their development. Biofiltration can effectively remove organic matter that is not able to be removed from water and biologically treated sewage effluent in conventional sewage treatment. The microbial attachment process, the factors that influence biological filtration, the kinetics of microbial growth and details of the microbial community in the biofilter are discussed in detail. There are several types of biofilters including submerged filters, trickling filter, bed filter, fluidised bed. The different biofilters are described and a comparison between them is provided. The application of biofilters for treating various types of wastewater effluent is detailed.