Environmental guidance for your business in Northern Ireland & Scotland

Managing wastewater at paper and card manufacturing sites

Managing wastewater at paper and cardboard manufacturing sites

This guidance is relevant if your paper business treats water or liquid effluents on site, such as using an effluent treatment plant.

Process water may be contaminated with chemicals and organic water-soluble pulp components. You need to treat and dispose of this wastewater correctly to prevent harming the environment.

Water pollution incidents involving dyes and suspended solids are the most common complaint downstream of paper mills. Make sure that you treat and remove colour from any wash waters before you discharge them to the environment.

What you must do

Before you discharge wastewater to surface waters or groundwater you must have authorisation from your environmental regulator. You will need to treat effluent extensively before you can discharge it to surface waters or ground waters.

Before you discharge wastewater to a sewer you must get permission from your water and sewerage company or authority. You may need to pre-treat your effluent before you discharge it to the sewer.

Your process water may be contaminated with a wide range of organic water-soluble pulp components. You must treat this process water before you can discharge it to surface waters or groundwater.

Comply with your authorisation conditions

You must comply with all of the conditions in your authorisation or you may be prosecuted and fined.

If you have an effluent treatment plant you must manage it carefully to comply with the conditions of your authorisation. For example, you may need to monitor and stay within specified limits for the main components of your discharges, such as: flow rate, pH, temperature, suspended solids, chemical oxygen demand (COD). These requirements and limits will be explained in your authorisation.

Discharges to water and sewer

Waste sludges and screenings

Materials discarded from your effluent treatment plant, such as sludges and screenings, are classed as waste. You must comply with your duty of care responsibilities when dealing with these and other waste.

Duty of Care: Your waste responsibilities

You may need to deal with some sludges and screenings as hazardous/special waste.

Hazardous / special waste

Good practice

The paper industry uses large volumes of water in the production process. You can save money on your effluent treatment costs and your water supply by using water more efficiently. You should recycle and reuse water within your process wherever possible.

Keep your wastewater streams separate. This will make it easier to reuse the water and also prevent large wastewater streams being contaminated with concentrated toxic streams.

Review your chemical use

If you use biocides for system cleaning, for slime control or within de-foamers, consider using biodegradable biocides that degrade quickly, such as guanidine and isothiazolones.

Avoid using chlorine-containing bleaches or chlorine-bleached pulps. Bleaching chemicals react with organics and place a considerable load on water treatment systems.

Don't overdose water with water treatment chemicals, especially those containing halogens (eg chlorine and bromine). For high organic loads use chlorine dioxide (ClO2) in place of halogenated disinfectants.

Use dyes with solid pigments where they can be abated by clarification.

For more information see our guidance on raw materials.

Effluent treatment plants

Make sure that your systems are designed so that effluent cannot bypass the treatment plant.

If you make a change to your process, always consider the effect this change will have on your treatment plant. Effluent treatment plants are designed for specific processes, depending on the quality and quantity of the effluent. For example, if you implement water minimisation measures the concentration of your effluent will increase.

If you carry out batch processes, you should manage your effluent carefully to avoid discharging large quantities to the treatment plant at one time. These 'shock loads' could affect the treatment plant's performance.

If there are a lot of coloured fines during de-inking, consider using dissolved air flotation (DAF) or membrane technology. You can use DAF as a primary effluent treatment, as well as in the de-inking process.

Balancing tanks can help to mix and standardise your effluent. Sludges with poor settlement characteristics (bulking) can be treated by stabilising fluctuations in effluent pH, flow, load and tank conditions and by maintaining your plant regularly.

Treat effluents containing suspended solids separately. This will prevent problems in biological treatment plants.

Cover containers to prevent emissions and odour from chemicals and sludge.

Monitor and maintain your treatment plant

Monitor your effluent plant regularly to make sure it is operating effectively. You could use turbidity meters to monitor effluent quality continuously. You could make someone responsible for inspecting and maintaining the plant regularly.

Check your sewerage and effluent disposal costs. Establish a baseline and investigate when costs deviate from it. This could save you money.

Employ suitably qualified engineers to make sure the treatment plant is designed to produce the required quality of effluent and that it will operate effectively.

Make sure you have enough storage capacity for the quantity of sludge your plants produce.

Minimise the amount of sludge you produce

Reduce the volume of sludge you produce by using dewatering presses or centrifuges. For example, use centrifuges to separate fines in white water and recover reusable material in your production process.

Reduce the load on your treatment plant by using waste minimisation techniques and monitoring the volume of water used by your business.

Recycle wastewater whenever possible to reduce the input and load on your water treatment systems. Reducing the water content of the sludge can reduce your waste management costs.

For information on water efficiency see our guidance on water use and abstraction.

SEE ALSO: Paper and cardboard sector guidance

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