Drinking Water Treatment
Municipal drinking water, sometimes referred to as potable water, is water that has undergone treatment and meets the regulatory requirements for human consumption. Drinking water can be delivered to the consumer from numerous sources including a public, or private, water system or as bottled water.
Raw water is collected from a variety of sources including lakes, rivers and underground aquifers. These sources can be contaminated, so the water requires appropriate treatment to remove potentially harmful agents before consumption. Most drinking water processes include steps for Coagulation and Flocculation, Sedimentation, Filtration and Disinfection.
Regulatory standards and oversight for treatment varies around the world. Many countries follow guidelines set by the World Health Organization. More rigorous standards are applied in the European Union, United States of America and other developed countries.
The most important parameters in drinking water treatment are:
Turbidity of the water is caused by undissolved particles. Since these can also be pathogens or other microorganisms or these are bound or enclosed in the particles or the particles can serve as food for such organisms, turbidity is an important parameter, especially in drinking water monitoring. In addition, this can corrosion and material damage in industrial plants.
Conductivity does not indicate a specific substance, but can give indications of changes in the mixing ratio of the constituents or salinisation processes and the mineralisation content, for example in groundwater near the surface due to fertilisation, wastewater, landfills or road salt and industrial discharges. In general, conductivity as a cumulative parameter indicates the content of salts in the water: The ions dissolved in water can transport electricity.
The pH value of water tells how acidic or alkaline it is. The measuring scale ranges from 1 to 14. A pH value of 1 means that the water is very acidic. A value of 14 means that the water is very alkaline. The pH value influences the chemical composition of the water and thus also the reaction with chemicals and with the environment. A stable pH value is therefore important for most applications.
Lead is a heavy metal and can often be found as a dissolved ion in water. For humans it is it is highly toxic to humans - with serious health consequences in the case of long-term exposure. Lead cannot be broken down in the body, but is deposited in the bones or organs. Regular monitoring is therefore particularly important for drinking water. Lead can also enter the drinking water system by leaching through (old) pipes. Other sources of contamination are pollution from industries such as mining and recycling processes. Lead is also present in some paints and paints and fuels.
Copper is a semi-precious metal. It is naturally present in water, but can also be introduced by humans. In small amounts, copper is even an important nutrient for the body as a trace element. In too high a dosage, however, it can have health consequences such as headaches, diarrhoea, vomiting, dizziness, depression and fatigue, and in the case of long-term exposure even anaemia, liver and kidney damage. An increase in the copper concentration in drinking water can also be caused by an incorrect pH value in the drinking water pipes, but also by other contaminants such as industrial water or agriculture.
Nickel is vital for some creatures in nature. In high concentrations, however, it is toxic. It can get into drinking water via components, fittings and pipes, but also through industrial contamination or waste incineration plants. Health consequences can include cramps and stomach ailments.
Nitrate is a natural metabolic product of nitrification and as such is naturally present in many waters in moderate concentrations. It is formed in the soil by microorganisms and is taken up by plants, which need it for growth. Nitrate compounds are highly soluble in water. Excessive levels in water can be harmful to health when it is converted into the toxic nitrite. Increased nitrate pollution can be caused by the washing out of fertilisers in agriculture and sewage treatment plant effluents. Nitrate also enters water bodies via rain.
Escherichia coli is a bacterium that belongs to the coliform bacteria group. It is found in every human intestine and is usually not a pathogen itself. However, E. coli bacteria are an indication of faecal contamination, which can subsequently carry pathogens.
These include primarily the genera Escherichia coli, Klebsiella, Enterobacter, Citrobacter and Ser- ratia. With the exception of Escherichia coli, these bacteria can also occur in the environment. However, they are also a general indication of faecal contamination caused by deficiencies in the treatment and piping system and in the pipe network and can result in pathogens.
The colony count tells how many colony-forming units of bacteria (CFU) per unit volume in ml are present in the drinking water. When the water sample is placed on a nutrient medium, colonies are formed, the number of which provides information about the invisible quantity originally contained in the sample. The colony count thus provides information about the overall microbiological condition of the water. Since some bacteria can trigger diseases or indicate the presence of pathogens, monitoring is particularly important in drinking water.
