Water treatment means that water utilities have in place effective processes to make water more acceptable for a desired end-use. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the concentration of such contaminants so the water becomes fit for its desired end-use.These can include use as drinking water, industrial processes, medical and many other uses. One typical use is returning water that has been used back into the natural environment without adverse ecological impact.
The water treatment processes involved in treating water for drinking purpose may be solids separation using physical such as settling and filtration, chemical such as disinfection and coagulation.
Water balance process is involved in swimming water treatment processes,this is a chemical process to make the PH level more acceptable.
Biological processes are also employed in the treatment of water and these water treatment processes may include, for example, aerated lagoons, activated sludge or slow sand filters.
Purification of potable water
Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for its intended use, most commonly human consumption. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, minerals such as iron, manganese and sulphur, and man-made chemical pollutants including fertilisers.
It is important to take measures to make available water of desirable quality at the consumer end. That leads to protection of the treated water during conveyance and distribution after treatment. It is common practice to have residual disinfectants in the treated water in order to kill any bacteriological contamination after water treatment.
Drinking water treatment processes
The combination of following processes is used for municipal drinking water treatment worldwide:
• Pre-chlorination – for algae control and arresting any biological growth
• Aeration – along with pre-chlorination for removal of dissolved iron and manganese
• Coagulation – for flocculation
• Coagulant aids also known as polyelectrolytes – to improve coagulation and for thicker floc formation
• Sedimentation – for solids separation, that is, removal of suspended solids trapped in the floc
• Filtration – for removal of carried over floc
• Disinfection – for killing bacteria
There is no unique solution (selection of processes) for any type of water. Also, it is difficult to standardise the solution in the form of processes for water from different sources. Treatability studies for each source of water in different seasons need to be carried out to arrive at most appropriate processes.
The above mentioned technologies are well developed and generalised designs are available which are used by many water utilities (public or private). In addition to the generalised solutions, a number of private companies provide solutions by patenting their technologies.
Agricultural waste water treatment
Agricultural waste water treatment relates to the treatment of waste waters produced in the course of agricultural activities. Agriculture is a highly intensified industry in many parts of the world, producing a range of waste waters requiring a variety of treatment technologies and management practices.
Industrial waste water treatment
Industrial waste water treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use.
Most industries produce some wet waste although recent trends in the developed world have been to minimise such production or recycle such waste within the production process. However, many industries remain dependent on processes that produce waste waters.
Sewage treatment is the process that removes the majority of the contaminants from waste water or sewage and produces both a liquid effluent suitable for disposal to the natural environment and a sludge. To be effective, sewage must be conveyed to a treatment plant by appropriate pipes and infrastructure and the process itself must be subject to regulation and controls. Some waste waters require different and sometimes specialized treatment methods. At the simplest level, treatment of sewage and most waste waters is carried out through separation of solids from liquids, usually by settlement. By progressively converting dissolved material into solids, usually a biological floc which is then settled out, an effluent stream of increasing purity is produced.