Water and Effluent Treatment Magazine
Issue link: https://read.utilityweek.co.uk/i/468709
22 WET NEWS march 2015 capital investment required to treat drinking water for nitrate concentrations alone is estimated to be between £5m-£12m a year, with the high carbon and operating costs of the treatment plants also of concern. What is the impact on the water industry? Steve Buss reveals all. The challenge: Overcoming costly nitrates treatment INSIGHT Water treatment the system retains the knowledge of what has been installed, which is particularly important if there is a change in asset ownership THE CONCEPT • nitrate contamination costs the UK water industry between £5m-£12m in capital investment a year • agricultural farming accounts for 50-60% of nitrate found in groundwater • the safe levels of nitrate in drinking water deemed by the UK and european standard is 50 parts per million (50mg/l) • around 75% of the South-east and 35% of england and Wales as a whole rely on groundwater to supply their drinking water NEED TO KNOW 1 recent findings suggest nitrate concentra tions in some of the worst affected groundwater sources may be levelling out 2 70% of the UK is recognised as a nitrate Vulnerable Zone and farmers operating in these regions are required to comply with stringent rules and guidelines 3 the nitrate Sensitive area scheme recognised drinking water sources that exceeded or were at risk of exceeding the directive, and voluntary agricultural measures were introduced by DeFra which saw farmers offered payments in return for complying with rules 4 engagement and collaboration is the key to reducing the amount of fertiliser used in farming 5 accelerating declining trends may allow water companies to defer or avoid investment in new nitrate treatment plants, which can save water companies' bill payers millions of pounds and reduce carbon emissions THE VERDICT • engagement and collaborative working may be the key to reducing surface run-off and direct contamination of nitrate into the public water supply. there still is a lot of nitrate in the system and there is still a lot being applied to farmland so any changes will be subtle. N itrate (NO3) naturally oc- curs in all surface and groundwater and is a compound that can arise both naturally and artificially, occur- ring as part of the nitrogen cycle during the bacterial breakdown of animal and vegetable pro- teins, but also as a direct result of farming, with the compound being one of the main constitu- ents of fertiliser. This means that the compound can enter groundwater when large quan- tities of fertiliser are added to the soil and has the capability to infiltrate sources such as riv- ers and open reservoirs through surface water run-off. Nitrate contamination of drinking water has long been recognised as a public health issue. The UK and European standard for concentration in drinking water is 50 parts per million (50mg/l), with water companies required to take remedial action to ensure the water is safe for human con- sumption. Nitrate can pose a threat to drinking water mainly because it is highly soluble and, once ingested, breaks down into nitrites. Although it does not pose a direct threat to older children and adults, very high levels can cause methemoglobinemia (blue baby syndrome) in infants and young children, and can potentially be fatal. Nitrate concentrations in soils have steadily increased fol- lowing World War II due to intensification in farming, how- ever it was not until between 1975 and 2004 that the true extent of contamination was known due to nitrate leaching delaying its emergence in groundwater. Since 1975, around 50 groundwater sources have been removed from use in the UK because of high levels of nitrate – equal to around 140 million litres of water a day lost from the national supply – around 2% of the current total water consumption in England and Wales About 75% of the South-east and 35% of England and Wales as whole rely on groundwater for their water supply and, as a major resource, with water pro- viders required to take remedial action and either blend the water with a lower source, or use specialised water treatment centres. The process of remediating the water is carbon intensive, and the energy used by the water industry contributes to 3% of the country's total energy con- sumption each year. For this rea- son, nitrate in groundwater has cost the UK water industry around £250M to date, with many of these costs passed on to the end consumer.