Water Treatment Systems for Agricultural Water Supply

Abstract

Review of the main water treatment methods recommended for application in water supply processes at rural settlements with a daily water consumption of less than 1,000 m³, and types of plants where these methods are in current use. One of the factors influencing the productive activities and social development of rural settlements is the water supply. A lot of attention is paid to problems related to the drinking water supply. In Kazakhstan, most water pipes and water treatment plants began operation or were overhauled more than 30 years ago. Outdated water treatment systems do not provide a high-quality water supply. More than 25 % of operational water pipelines do not meet the sanitary requirements. More than 90 % of rural settlements in Kazakhstan are supplied from underground sources (wells, percolation wells, tapping of springs); only the remaining 10 % are from surface sources. The conditions of rural water use (less than 1,000 m³ a day), the lack of skilled repair personnel and the intermittent electricity supply necessitate the use of compact, energy-saving and nonchemical means of water treatment. Looking through patents and the literature for recent years shows that the basic methods of domestic water improvement are still clearing, decolouration, softening, fluoridation, defluoridation, desalination and disinfection. Thus, taking into account the above review of the main water treatment methods and the types of plants at which reverse osmosis treatment can be applied the following methods are recommended in the water supply systems of rural settlements with a daily water consumption of less than 1,000 m³. For water clearing and decolouration, low-rate filters should be applied. Local close-burning shungites and zeolite (“Koksu” deposit) can be used as a percolation bed. For hard water with a high fluoride and iron content use the “Struya” water treatment unit. For softening, apply liming, soda lime and the sodium cycle (equipment produced by LLC “Membrane technologies C.A.”); for deferrisation and permanganating, filter with preliminary aeration using equipment produced by “Aikos”; for defluoridation, apply an ion-exchange pressure filter with an alumina filter bed (Al₂O₃); for disinfection, apply a UV sterilizer (LLC, “Membrane technologies C.A.”); for desalination/deionization, apply reverse osmosis modules arranged in the internal chamber of the well casing (LLC “Kazakh Water Economy Research Institute”).