Lillian Tong July 21, 2022

The shortage of heavy truck drivers has put pressure on the UK’s chemical supply chain for wastewater treatment. Therefore, the government told British sewage treatment plants that they could discharge sewage that had not been completely treated if necessary.

The UK water trade agency has determined that the distribution of ferric sulfate by a few water companies has been disturbed. It is used to remove phosphorus from waste water. A spokesman for the British water company pointed out that the problem was the national shortage of HGV drivers, and they did not think the situation would improve in the short term. They also stressed that the shortage had not affected the treatment of drinking water.

The chemical business association, which represents the UK chemical supply chain, found that 96% of its members are currently experiencing transportation problems in the UK, up from 63% in June. As early as June, it warned the government that the shortage of drivers would affect the supply of water and key agricultural chemicals.

Tim Doggett, CBA’s chief executive, said the UK’s supply chain was deteriorating. ‘we think the impact of the shortage of drivers may get worse before it gets better,’ he said. He added that the chemical industry may be hit harder than other industries because drivers carrying dangerous substances need to have additional qualifications.

Generally, the sewage treatment plant needs to obtain a license to discharge the treated sewage into surface water or underground water. The permit contains conditions to control the quality of discharged sewage. The Environment Agency for England said that if sewage treatment plants cannot obtain the necessary chemicals that meet the conditions of the license, they can still discharge sewage. This applies only when the reasons for their lack of access to chemicals include the new relationship between the UK and the EU, epidemics or other inevitable supply chain failures.

According to a government spokesman, this action is a time bound preventive measure with “sufficient conditions” to mitigate risks to the environment. “The most sensitive and high-risk watercourses will not be affected. Any company planning to use this short-term measure must first reach an agreement with UNEP, which will check its compliance.” At present, no company has applied.

Low short-term risk

Ferric sulfate is used to remove phosphorus from wastewater to reduce nutrients discharged into waterways. It is usually the third stage after biological treatment of sewage to remove solids and organic matter.

A spokesman for British water said: “in some isolated wastewater treatment plants, phosphorus content is likely to increase and the level of phosphorus is likely to increase.” However, this exemption does not apply to sewage treatment plants that may have a significant impact on the environment or downstream sewage extraction.

M å rten krogerus, a water treatment technology expert of afry, a Finnish consulting company, explained: “the purpose of tertiary treatment is to remove residual pollutants, especially phosphorus, which can be effectively precipitated by iron salt and separated from wastewater by sedimentation or flotation.” “Without ferric sulfate or any other iron / ferrous salt, the third stage of treatment cannot operate normally.” Therefore, the discharged wastewater will contain higher concentrations of phosphorus, as well as organic matter and nitrogen. ”

Kroggs said that over time, the increase of phosphorus load will lead to eutrophication and algae growth. “However, the impact risk of short-term iron sulfate shortage is relatively low, but the long-term shortage may have more serious consequences.”

Other iron salts or ferrous salts, such as ferric chloride or ferrous sulfate, can be used instead. Alternatives such as alum and polyaluminum chloride are also possible, although they are more expensive, kroggs said. However, the supply side challenges may be the same for them.

Anna Suarez, a professor of biotechnology engineering at the University of Cranfield, said she was surprised to hear the announcement by the UK Environment Agency, which is famous for its strict environmental protection measures. However, she believes that the agency will give priority to the discharge and protection of “sensitive” rivers, such as those with low environmental quality or high agricultural runoff. “The water industry in this country relies heavily on chemical phosphorus removal. Perhaps this will encourage it to consider other technologies rather than relying entirely on chemicals. European countries have used a series of methods, such as biological nutrient removal, but only Severn Trent water uses biological based removal.”

At present, the British water company has not found any supply problems of other chemicals. Kroggs said that the availability of other key wastewater treatment chemicals such as urea and phosphoric acid is critical to the good performance of biological treatment plants and sludge dewatering. The lack of these chemicals will “relatively quickly” lead to poor performance of wastewater and an increase in the concentration of final discharge, especially in the absence of tertiary treatment. “This (English) development is worrying. In addition to the consequences for production, it may also lead to non-compliance with the required release agreement.” This may result in penalties, restrictions on industrial production, and even prolonged downtime of industrial activities.

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