Ever-tightening legislation around the quality of effluent being accepted by water companies, coupled with a severe shortage of capacity at hazardous waste incinerators, is putting major strain on UK businesses.
That’s the view of Phil Manley of leading waste management company CSG, who said it is inevitable some manufacturers will fail as a result of the enhanced rules around effluent quality– and customers will end up paying more for products.
Trade effluent control
Any discharge to a public sewer from a commercial or industrial premises is classified as trade effluent and, under the Water Industry Act 1991, it is an offence to make this discharge without the consent of the local water company.
This affects a wide range of businesses, including food and drink producers, metal finishers, engineering business and construction works.
It’s almost 100 years since the first piece of dedicated trade effluent control legislation was introduced in England and Wales in 1937. This ground-breaking legislation gave the occupier of a trade premises the right to discharge trade effluent into the public sewer, subject to the consent of the regulatory body, which is most commonly the local water company.
Consent can be subject to various conditions, including the composition of effluent, the flow and, most significantly, the quality. It is an offence under criminal law, punishable by a fine, to discharge without consent or in breach of conditions included in a consent. A water company is under no obligation to issue a consent.
Water companies themselves are under increasing pressure from The Environment Agency (EA) to ensure effluent is clean and within strict limits of chemicals and contaminants before the water is discharged into controlled water sources such as rivers, streams, lakes, canals, coastal waters, estuaries and groundwater.
Water companies can be subject to huge fines if they are found to have discharged illegally.
Inevitably, water companies are demanding that the effluent they receive from industrial customers is hitting increasingly higher standards with fewer chemicals and contaminants present, meaning less work is required before the water is returned to controlled water sources to start the cycle again.
“Legislation around what chemicals can be discharged into controlled water sources has been tightening all the time,” said Phil.
“The EU was the driving force behind the rule changes – and it still is in a sense as many of the laws we’ve adopted since Brexit have come from EU legislation.
“This is a good thing as we all want the water being pumped into our rivers and seas to be as clean as possible.
“The problem is that when the EA imposes improved quality limits on water companies, it is often passed down the line to trade effluent dischargers. The onus is on the business creating the liquid waste to improve standards rather than the water company.
“Ultimately, water companies are privately owned so they are loathed to spend more than they need to meet the new criteria. Instead, they control the effluent being discharged to them. They have no control over domestic properties so they control what they can – the liquid waste from industrial customers.”
“ammonia levels have been a key target of the EA for some time, with strict limits now in place”
Companies producing the effluent have a legal obligation to tell the water company what is in it – and regular sampling is carried out to ensure it is falling within the agreed parameters. Failure to do so could see a business’ consent removed or large fines imposed.
Keeping ammonia out of our water
Ammonia levels have been a key target of the EA for some time, with strict limits now in place. Ammonia can cause unsafe sewer atmospheres and can also cause toxicity issues within a watercourse as ammonia is highly toxic to the aquatic environment. Ammonia is a by-product in a number of industries, including milk processing, fruit and vegetable manufacturing, potato processing and breweries.
In order to hit the EA-imposed limits for ammonia levels discharged into controlled waters, water companies prescribe a limit to trade effluent discharge customers. If the local sewage treatment works has no biological treatment for ammonia, then the limits set will be much lower than for a treatment plant with biological oxidation of ammonia. There is no national limit for ammonia discharge so, instead, businesses are constrained by the type and scale of sewage treatment available locally.
Phil warned: “Reducing levels of ammonia in controlled waters is desirable, as it is toxic to aquatic life. However, ammonia removal
can have unintended consequences when it is carried out through a biological treatment process.
“The bacteria used in these processes generally convert ammonia into nitrites and then nitrates. Nitrates are not usually toxic at these concentrations, so this solution helps to protect aquatic life.”
Nitrates and eutrophication
Nitrates are commonly known as an important source of fertiliser. However, the build-up of nitrates in river basins and coastal waters have caused well documented issues with eutrophication.
Eutrophication is the process where water becomes enriched with nutrients and minerals, ultimately creating a hospitable environment for certain types of algae. Whilst this may seem innocuous at first, the problem arises where algae grow to such an extent that sunlight is unable to reach bottom-dwelling organisms. This is known as algal bloom and is the first visible sign of eutrophication.
Algal bloom also causes the reduction of dissolved oxygen levels in the water, which reduces the numbers of fish and crustaceans which can be supported. This in turn impacts the wider eco-system. For example, certain species of birds may no longer have access to their food source. The algae themselves can also be toxic.
Coastal waters and estuaries are particularly vulnerable to eutrophication. As these areas are often unique habitats and home to a diverse array of species, there has been much publicity surrounding the issue of eutrophication caused by the build-up of nitrates.
Examples in recent years include Poole Harbour and Chichester Harbour, both situated on the south coast of England. Both are considered as important areas for wildlife conservation and home to some unique habitats.
Phil said: “The build-up of nitrates and minerals such as phosphate has always been an issue. Agricultural run-off from farmland is a significant source of nitrates in watercourses.
“However, the increased focus on ammonia treatment certainly hasn’t helped matters. It goes to show that in dealing with one problem, without careful consideration, it’s easy to create more issues further down the line which in turn can be difficult to solve.”
Technologies to remove nitrates from wastewater typically involve extra biological treatment. After its ammonia content has been digested into nitrates, passing the effluent through an anoxic (low oxygen) zone encourages the growth of bacteria known as denitrifiers.
These bacteria break down the nitrates as a source of oxygen for respiration, allowing free nitrogen to escape into the atmosphere as a gas.
Phil said: “This type of process will deal with much of the nitrogen content in effluent. However, it takes time to build and requires investment. It also requires additional space, which may not be available at existing treatment works.
“Nitrates are a consequence of ammonia treatment, which is produced from household wastewater as well as industrial. In some areas, the lack of nitrate treatment capacity has led to a reduction in house building activity.
“This has put the brakes on development and put the Government at risk of failing to meet its own house building targets, so the issue must be resolved in the long run.”
A report published by HBF (Homebuilders Federation) in March 2023 estimates that nutrient neutrality targets across 74 local authorities will prevent the construction of an average 41,000 homes annually.
The EA has also taken aim on reducing polycyclic aromatic hydrocarbons (PAHs) in effluent, as well as persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs).
Phil said: “These chemicals are essentially non-biodegradable, meaning they remain in the environment indefinitely. Because of the persistence of these chemicals, national government is investing a great deal of effort into banning their use, which has been done for PCBs. There is, however, evidence that materials which are no longer being manufactured are still present in products today, even though they are no longer being used.”
PCBs were used in transformers as they had excellent insulating properties, but it wasn’t known at the time they were non-biodegradable. Old PCB oils were removed when they were banned in 1977 and the transformers were refilled with new oil, but residual traces contaminated the new oil, up to as much as 1,000–2,000 ppm. When this oil is emptied to be replaced and the transformer refilled, there is often still PCB contamination, albeit less than before.
Phil said: “Whenever old transformers are emptied, they are still contaminated with PCBs. It will not biodegrade, not even in 100 years. It gets into marine life and ultimately higher organisms such as mammals.
“PCBs have been shown to cause a variety of adverse health effects and are associated with acne-like skin conditions in adults and neurobehavioral and immunological changes in children. PCBs have also been classified as probable human carcinogens.”
PFAS (Perfluroalkylsulfonates), meanwhile, were used widely in firefighting foam. Because firefighting foam is only used in a fire, there is a lot of this material in storage around the world. It is gradually being replaced, but the PFAS must be incinerated when removed. The EA is looking to limit PFAS concentrations from sewage treatment works. As an indication of the proposed concentration limits, the US EPA (Environmental Protection Agency) is considering limits of as low as 0.01 parts per trillion in drinking water.
Phil said: “If similar limits are imposed by the EA on UK sewage treatment plants, then the sewage treatment works will pass it on to their trade effluent customers. This is one milligram per thousand litres, the size of an Intermediate Bulk Container.
“At these very small concentrations, this is less than the normal background levels you might expect to find. It’s almost impossible to analyse for these chemicals at such small concentrations, meaning it can be difficult to find the source.”
Complying to regulations
Manufacturers which create effluent containing monitored chemicals can consider a range of approaches to remove the chemical before the wastewater is sent to the treatment works, including biological, chemical or physical processes.
It is possible to acclimatise a biological system for effluent – but it may not be suitable for a normal sewage treatment works. Some pharmaceutical companies have developed their own biological treatment plants designed to treat their effluent containing organic matter. Bacteria can be acclimatised to treat effluent from complex organic processes. This can be an expensive option and is most appropriate for effluent containing complex organic compounds.
Chemical oxidation processes are normally based around hydrogen peroxide and use UV light as a catalyst. Its use is limited to organic substances but is not able to degrade some of the more complex organics such as PAHs and PCBs. It is quite effective on some simpler organic toxins, such as phenols. Where effluent contains simpler organics, this process can be a useful pre-treatment to remove these compounds prior to sewer discharge.
Available treatments and solutions
Reverse osmosis is a technology which uses semi permeable membranes to concentrate effluent. They will exclude salts and most dissolved solids and only let water through the membrane.
The membranes are reusable. In order to force the water through the membrane the osmotic pressure has to be overcome. Achieving this can require pressures of up to 80 bar, so it needs to be pumped through which requires a lot of energy. The membranes need regular cleaning to allow the system to work at optimum efficiency. An effluent of river quality can be achieved using this process.
Phil said: “This is used frequently on landfill leachate. It still produces a concentrate, so if it is used for industrial effluent the objective is to achieve the minimum amount of concentrate. If the effluent has a high salt concentration, this process would be less effective so an evaporation process would more appropriate.”
One of the most common solutions is evaporation – but that itself causes headaches.
Evaporation technologies currently available are generally based on vacuum distillation using electricity as the heat source. The water produced from this process is quite clean and free of dissolved salts but may contain some volatile organic compounds which have co-distilled with the water. However, this water may well be suitable for sewer discharge as a high proportion of the contaminants have been removed. Unfortunately, with concentration processes there is a small amount of concentrate left for disposal. This can be as high as 20% of the original or as low as 1%.
Phil said: “If you evaporate then you’re left with the clean effluent which can be sent to the treatment works, but you’re also left with a concentrate. If it can be proven to be non-hazardous it can be sent to landfill but then you’re just sending it on to another environment.
“However, most of the time the concentrate is hazardous – and the only way to get rid of hazardous concentrate is by incineration.
“Businesses might create 100 tonnes of effluent a day. They could manage to clean the effluent to the required levels but then they’re left with 10 tonnes of concentrate which needs to be incinerated.
“You’ve no chance of having that waste incinerated in Britain because the capacity just isn’t there.”
Businesses need more support
Phil accepts that strict controls over what chemicals are entering our controller water sources is important – but businesses are being put under huge pressure.
“Reducing chemicals and contaminants in effluent is important, ultimately for the health and quality of our waters,” said Phil.
“It is, however, important that businesses are given realistic timeframes to implement changes when they are brought in. Some of the separation techniques are not easy and cannot be done overnight.
“I would also back additional Government support for businesses to introduce new technologies such as evaporation or reverse osmosis. This could come in the form of grants or interest free loans so that businesses can plan for the future and not be sent under by sudden expenditure.
“Crucially, decisions around effluent need to be made holistically so that the whole picture and probable knock-on impacts are considered.
“Some businesses might well go to the wall if they can no longer keep their effluent at the required levels. Some will absorb the extra costs but they’ll inevitably pass it on to customers.”