Wastewater is defined as any water that has been recycled back into the sewage system, down your tap, your toilet, from industrial use, farm run-off or a host of other sources. That wastewater has to go somewhere, and usually, it heads to the local processing plant to be treated before returning to the natural water system via rivers or the sea.
However, wastewater by its very nature is full of pollutants. These range from large, solid matter like nappies, plastics and even the odd tyre, down to chemicals that can do serious damage to the environment if allowed to go unchecked. Let’s have a look at the most common wastewater pollutants, and how we deal with them.
We pour a surprising amount of pollutants down our plugholes each day. From the shower gel we use in the morning, through to flushing plastic cotton buds away down the toilet – everything we send into the water treatment system needs to be removed before the water re-enters the natural system.
This is a hot topic, as the public has become aware of just how damaging these tiny grains of plastic can be. Not only are they small enough to pass through most filtration systems, but they’re small enough to be ingested by wildlife. That means microplastics, like microbeads in face washes, and even fine filaments from your clothes, are re-entering the food chain that leads, eventually, to your dinner plate.
Changing the oil on your car is a job we all have to do, but pouring the spent oil down the drain is an absolute no-no. Just a tiny bit of oil can cause enormous damage, spreading much further than you’d think. The same applies to used antifreeze, brake fluid, or other liquid contaminants. Dispose of them properly through your local waste management centres, and not down the drain.
Household cleaners are a cocktail of contaminants, ranging from ammonia through to caustic soda, ethylene glycol butyl, and a host of other unpronounceable chemicals. We need to keep our homes clean, and most water treatment systems are able to remove the worst of these. But try to minimise the number of powerful cleaning agents you use to clean your toilet or scrub your oven.
One of the biggest problems facing sewage system operators is ‘fatbergs’ – huge lumps of congealed fat and detritus that can grow to enormous size (a fatberg the size of a London bus blocked one of the capital’s largest sewers in 2013. It weighed in at 130 tons, was 250 m long, and was made up of waste and fat flushed into the system by homes and restaurants). The fat you pour down your sink can contribute to these fatbergs, making them incredibly difficult to remove.
The only thing that should be going down your toilet is the ‘Three Ps’ – that’s pee, poo, and paper. So-called ‘flushable wipes’ are often not as flushable as you might think, and one of the commonest pieces of household plastic found on beaches are plastic cotton buds.
The most common types of industrial pollutants are chemical spills or accidental discharges of contaminated wastewater. Businesses are very strictly monitored by the Environment Agency, and any large business found contaminating the water supply risks prosecution and very high fines. Accidents do happen, though, and when they do the water companies have well-rehearsed protocols in place to minimise the impact on the environment and to clean it up as quickly as possible.
Farming contaminants such as pesticides, fertilizers, and even animal faeces, can contaminate the water supply. Field ‘run-off’ often gets directly into water courses that surround fields and can spread further downstream very quickly. Field run-off is usually indicated by the water changing colour and a frothy brown foam floating on the top of the water.
Nature occasionally throws us a bit of a challenge, and if conditions are hot and dry then reservoirs and lakes can sometimes suffer from blue-green algae contamination. Not all blue-green algae is toxic, but if it is then the Environment Agency, in conjunction with the local water company, will ensure it doesn’t become a danger to the public and may even halt the use of the location as a water source until the bloom dissipates naturally.
What are we doing to prevent wastewater pollutants?
The water treatment system your water goes through at a treatment plant is a comprehensive system designed to remove the vast majority of contaminants. Your household waste isn’t usually a problem, and any natural contaminants are dealt with by the ‘good’ bacteria used to digest them during the process. Larger pollutants such as litter can be pulled out relatively easily, but there are still issues with contaminants like micro-plastics, that can get through the finest of mesh traps.
In this instance, we need to tackle the problem at source, and that means providing the public with the information they need to try and stop these pollutants at the source. In some cases (as with the use of ‘microbeads’ in beauty products), we also need to encourage manufacturers to find more environmentally-friendly alternatives, or even put in place an outright ban on them.