oa Reuse of treated sewage effluent (TSE) in Qatar and its impact on sustainability and the environment

Water is an important natural resource and is necessary for the survival of all living things. With industrial development and the increase in population, there has never been more demand on water resources like what we are seeing today around the world. Moreover, climate change effects such as droughts and desertification is a problem many countries are facing, especially in the Middle East and North Africa. Qatar is one of these countries with very limited water resources, yet the demand on water is great due to its vast industry and continuous increase in population. It is one of the most dry and arid regions in the world which is facing inconceivable challenges in protecting fresh water for domestic, agriculture and industrial uses. Thus, reusing treated sewage effluent (TSE) will be essential to overcome the water scarcity in this country. Although the reuse of TSE is vital to save water and sustain the environment, it may adversely affect the environment if the treatment process is inadequate. Sewage effluents contain numerous contaminants which should be removed completely before being discharged or reused. A wide range of these contaminants are persistent to the conventional treatment processes such as pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs). PPCPs and EDCs are regularly used all over the world and normally their final destination is the sewage water. Due to insufficient removal, they are discharged into the aquatic environment carrying adverse effects on the aquatic creatures, animals, and also humans. It is suggested that TSE goes through an advanced treatment process to minimize the environmental concerns due to the contamination with PPCPs and EDCs. This project aims to analyze the TSE produced in Qatar for the existence of a variety of PPCPs and EDCs. A pilot plant with an advanced treatment technology called advanced oxidation processes (AOPs) will be used to study the removal of these compounds. The AOPs to be studied will be based on different combination of ozone, hydrogen peroxide, and ultraviolet light. AOPs enhance the water treatment process by the production of the highly oxidizing hydroxyl radicals (OH√). In the preliminary tasks the TSE was analyzed for the total organic carbon (TOC) concentration as well as a variety of ions. The TOC and phosphate showed elevated concentrations of 5.02 and 1.33 ppm respectively. Jar test experiments were conducted to reduce these compounds by coagulation using ferric chloride and alum. TOC was decreased by 33% while phosphate was removed completely when the coagulant dose was ≥ 50 ppm. The removal of TOC is important prior to disinfection to avoid the formation of trihalomethanes (THMs) which are suspected carcinogens. According to the United States Environmental Protection Agency (US EPA), the TOC concentration should not exceed 2 ppm. This project has an influence on the sustainability of the environment by saving water, reducing energy consumption (required for desalination processes), and eliminating environmental pollution.