HAVE you ever flushed the toilet and wondered 'I wonder where that goes'? Chances are if you live in Mold or surrounding villages like Sychdyn, Mynydd Isa, Pantymwyn or Bryn y Baal, than the answer is Mold Waste Water Treatment Works which processes the 'outgoings' from around 22,000 people across the region from it base on Bromfield Industrial Estate.

Earlier this month, the works threw open their doors to the public with the aim to show people who the works serve the crucial role it plays in protecting public health and keeping the environment clean and safe.

While maybe not the most enticing idea for a day out I jumped at the chance and alongside a group of excited school children I joined one of the guided tours to learn about the sights and smells of the works and discover how sewage is cleaned and investigate how pollution impacts on our natural environment.

"Most people know that Welsh Water provide tap water for our homes but not as many realise that we also treat the waste that goes down the drains and the toilets," says Nigel Lee, catchment manager (North East) at Welsh Water, as he shows us the inlet works where the initial stage of raw water and wastewater treatment begins with the removal of solids.

"The wastewater comes from sinks, laundry, toilets in your homes, as well as industrial waste and rainwater and we can treat up to 92 litres of wastewater every second or nearly 8,000 cubic metres every day which equates to 10,000 bathtubs or 22 swimming pools each 24 hours."

As Nigel explains, blocked sewers are a major problem which costs Welsh Water over £7m a year to clear. They cause huge human misery, and every year flood hundreds of homes and businesses and can pollute rivers, beaches and the wider environment.

"Welsh Water deals with over 2,000 sewer blockages every month and the majority of these blockages are caused by everyday items put down the toilet such as wet wipes, sanitary towels and cotton buds, as well as fat, oil and grease that people put down their drains," says Nigel. "We screen out approximately 50 skips full of waste at the inlet to the works every year - that's about the same weight as 15 double decker buses. All this waste has to go to the landfill site."

Reducing the waste that comes out of the works is a top priority for Nigel and his team and it's interesting to not that Welsh Water is unique among the 10 water and sewerage companies in England and Wales in that it is ' Not for Profit' and does not have any shareholders.

"Apart from the plastic materials everything we receive here is recyclable," says Nigel. "Everything from grit which can go back to making roads and footpaths to the sludge that we take out which can be broken down and used as methane biogas.

"This is collected and used to run engines that provide heat and power to run our treatment plant. We also treat the biogas and inject it back into the mains gas supply which feeds homes in the area."

Joking with the children about how they've found a few sets of false teeth and toys before, not to mention a wedding ring that turned up at their Anglesey works recently, Nigel becomes even more engaged as we reach the 'Activated Sludge Area' where air or oxygen is blown into raw, unsettled sewage to smash the solids and develop a biological 'soup' which digests the organic content and pollutants in the sewage. The term "activated" comes from the fact that the particles are actively teeming with beneficial, sewage digesting bacteria, and protozoa which we later get a chance to view under the microscope after the tour.

"We remove 12,000 cubic metres of liquid sludge every year or 600 tonnes of dry bio solid," says Nigel proudly. "The sludge is transported to our site in Wrexham where it is treated further to kill any remaining bugs, then it is thickened to produce a dry 'cake' which is used as a fertiliser on fields to grow crops."

According to Nigel, there has been a wastewater treatment works on the site since the 1930s although today the scene is very different with most of the processes automated and only one member of staff needed.

"Many years ago treatment was all about removing large solids from the effluent and it was very much like how a septic tank operates," he says. "Today the level of biological treatment needed to reach the standards we need to achieve to look after our rivers is far more sophisticated and there are very tight controls on the operation to make it as efficient and effective as possible.

"The wastewater treatment process removes over 90% of biological and chemical contaminants that would otherwise pollute our rivers. It also removes ammonia which is poisonous to fish and other wildlife in the river and nutrients that would cause plants and weeds to overgrow and affect the river quality."

Last year Welsh Water's status as a 'not for profit' company allowed them to invest an extra £34m from customer's bills into the service which they maintain is heavily customer-driven through various events and the opportunity to 'have your say' on the company's website and social media.

"I've worked in this area for six years but I've been involved in the water industry for 20 years and waste treatment is a passion of mine," adds Nigel. "I'm interested in the process and the biology that is involved but also you'll find that most of us who work in this industry have a really keen interest in the environment.

"The important thing about days like this is that we really want to get the message over about what we do and share our experiences with the children - maybe we're talking to employees of the future."