This technical wastewater treatment guide turns the spotlight on the challenges faced by UK businesses involved in the metal fabrication and finishing industries. It looks specifically at their obligations to treat industrial wastewater and trade effluent prior to disposal or reuse. The guide looks at the issues facing metal fabricators and the regulatory environment including effluent consents, exemptions and waste management licences. It considers how wastewater quality can be controlled, how to deal with waste containing metal hydroxide, and from electroplating processes. It concludes by summarising a number of practical steps that can be taken to improve environmental performance and reduce trade effluent costs.
Dealing with wastewater in metal fabrication industries
Any operation which is involved in metal fabrication and finishing and produces wastewater on-site must consider what to do with the effluent which is produced as a result.
In these types of metal fabrication industries, it is highly likely that untreated effluent will contain metals from the different processes.
If this metal contamination is not removed from the resulting effluent it can cause significant damage to the treatment beds at the local sewage works, potentially leading to serious water pollution and other issues further down the line.
Furthermore, in most cases knowingly polluting water in this way is considered a criminal offence.
Polluters could find themselves in serious trouble with very hefty fines, or in the worst-case scenario, be forced to stop their metal working operations until the problems are resolved to the satisfaction of the regulator.
Trade effluent consents, exemptions and waste management licences for the metal fabrication sector
Any company, including metal fabricators which operate an on-site effluent treatment plant or ETP should investigate whether they need a formal consent to discharge their trade effluent into the local water system, a licence for waste management, or if they can register for an exemption from the requirements.
If your business has been advised that you do need a waste licence, you’ve been granted an exemption or you have obtained a trade effluent consent, this will come with a list of specific terms and conditions that must be met.
It’s important to recognise that you have a legal obligation to comply with the terms and conditions set out in the consent agreement.
Again, failure to comply with these conditions is a serious matter, which in some cases may result in significant fines, and in the worst cases a prison sentence.
Operators should also consult with the appropriate regulator before discharging any trade effluent – whether treated or untreated – into groundwater, surface water or through the public sewer system.
Depending on the situation, you may also need official written consent or some other form of authorisation… so it’s best to check.
Controlling the quality of effluent from metal finishing operations
In most cases, the best way of treating the effluent from your metal fabrication and finishing processes is by carefully controlling the pH levels of the waste streams.
Controlling the pH levels of the effluent allows any metal contaminants to be filtered out of the wastewater as solids.
Metal fabricators also have further responsibilities to manage the way in which their liquid waste is disposed of, and this includes any sludge which is produced.
Dealing with waste containing metal hydroxide
Special care should be taken over any waste material which contains metal hydroxide precipitate.
Waste containing metal hydroxide should be kept as pH neutral as possible.
If exposed to acidic conditions, then the metals may become active again.
Waste from electroplating processes
Filter cake which is produced from the filtering and treatment process in companies working in electroplating must be classed as special or hazardous waste for disposal purposes.
Dealing with wastewater containing metals from fabrication processes
For any metal fabrication business looking to optimise its environmental performance and reduce its trade effluent costs, the best advice is always to try to reduce the overall load placed on its effluent treatment plant by keeping the liquid waste which is produced to a minimum.
Wastewater treatability study
Testing your wastewater to identify its problematic components, and then using this information to optimise effluent treatment processes can, for many metal fabricators improve their environmental performance and save costs.
Monitor water volumes
It pays to look closely at the volumes of water which the business uses and look to minimise them where possible.
You should also carefully monitor the pH levels of the effluent produced as this will stop aluminium, zinc and other metals from precipitating back into the effluent.
Any settling tanks should be covered to stop effluent forming clumps of solids because of high temperatures.
Filter press efficiency
The filter press efficiency should also be managed on a regular basis.
Sludge water content
Reducing the water content of the sludge may have the knock-on effect of reducing waste management charges also.
Other wastewater treatment techniques to consider
There are other methods which may be equally appropriate in managing metal effluent quality and keeping it within the limits needed for discharge.
These could include the use of evaporation, specialist filtration including reverse osmosis, electrolysis and ion-exchange.
Wastewater and trade effluent solutions for metal fabrication and finishing industries
Water Treatment Services offer a comprehensive range of trade effluent and industrial wastewater management solutions.
Find out how we can help reduce your costs, achieve regulatory compliance and improve environmental performance.
Our industrial wastewater experts can provide advice and full support to help you identify the most appropriate strategies for managing your metal contaminated industrial wastewater and effluent streams.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained engineers, wastewater specialists and technicians we offer cost effective environmental support solutions across the whole of the UK and Ireland.
Contact us today to learn how our wastewater management solutions can help improve environmental performance, reduce costs and achieve cost effective discharge consent standards.
Improve your skills… learn more about our advanced wastewater treatment training courses.