WATER AND WASTEWATER

WATER AND WASTEWATER

Water is a precious resource which we all need to survive, and since Roman times Engineers have been designing ways of bringing clean, fresh water to people and removing contaminated water to prevent against the spread of waterborne diseases.
Most people are familiar with the water cycle: water evaporates, forms clouds and rains. The rain then makes its way back to the sea via land, rivers, lakes and aquifers. Humans operate in the middle of this cycle, water is extracted for a wide range of reasons, we usually clean it depending on the extraction point and the intended use. After we use it, we return it to the environment, at this stage it can be considered wastewater. Historically, there was less attention on the quality of the wastewater returned to the environment but has changed with the introduction of the Water Framework Directive in 2000 and the Industrial Emissions Directive (IED) in 2010. Since then the EPA and other organisations have been able to introduce more and more legislation which ensures that the wastewater we return to the environment is of a higher standard.

When most people think of wastewater, they think of the septic wastewater from toilets only and wastewater from industry is overlooked, even though most industrial processes will require water for cleaning and/or process water. Many industrial wastewaters have a relatively high polluting potential. For example, a medium-sized distillery could produce wastewater equivalent to 50,000 people, this is referred to as the population equivalent (PE) when comparing the scale of various wastewater treatment plants. The polluting potential of wastewater from industry is often due to a wide range of chemical compounds, all of which have a cost associated with separating them from the clean water. The three main pollutants are various forms of Carbon, Nitrogen and Phosphorus. Generally, energy and chemicals are used to separate these into the clean water and sludge, sludge has a high concentration of these pollutants and is sent to landfill if it is a chemical sludge or spread on land if it is a safe biological sludge. Before 1999 sludge would have been loaded onto boats and dumped at sea. However; Water, Carbon, Nitrogen and Phosphorus are valuable resources each with their own natural cycle and these intersect during wastewater treatment. Our modern society is trying to move away from the linear model of taking resources out of the ground, using them and discarding them. Instead, efforts are being made to develop a circular economy where water, energy and nutrients can be recovered and reused wherever possible.

Over the past number of years, the Industrial Emissions Directive has been evolving to include lists of recommendations for various sectors, these are known as Best Available Techniques (BAT) conclusions. They include a wide range of measures to ensure better energy efficiency, increased water, energy and nutrient recovery and tighter emissions limits. The EPA Environmental Protection Agency has started phasing in the enforcement of BAT regulations for certain sectors and this will result in many businesses needing to upgrade their wastewater treatment plants.

Our goal is to assist our clients to become BAT compliant or at least develop a roadmap of how they are going to get there. However, in many instances, we advise our clients to go beyond the BAT requirements. Wastewater treatment was previously considered a liability and an unwanted cost in many businesses, but now if the right technology is applied in the right situation wastewater can be considered an asset. For this reason, the term wastewater can be misleading and, in some instances, unfairly derogatory. Using terms like coproducts and by-products help to communicate the value and/or the potential cost savings available from changing how wastewater is managed and treated.

For example, energy can be recovered via heat exchangers or anaerobic digestion where the carbon in wastewater is converted into a biofuel. Phosphorus recovery via enhanced biological phosphorus removal can remove the need for large quantities of certain chemicals and fertiliser products can be developed by struvite precipitation. Other advances include nitrogen removal using advanced instruments to drastically reduce energy requirements. Technologies which would have, at one time, been reserved for high-value processes inside a factory are now being applied to wastewater treatment processes. The costs of these technologies are reducing which helps, but the value of clean water and resource recovery is also increasing. The world has less tolerance for businesses which pollute the environment and more respect for those who businesses who are environmentally friendly and who contribute to the circular economy. An area which our clients are conscious of and actively seek our assistance to achieve their goals, to increase productivity, efficiency and to improve their green credentials. Our engineers provide site-specific solutions to achieve those goals.

WEW Engineering is an independent company with highly skilled and experienced team members. We are consulting and design engineers, and we offer a wide range of services relating to Water, Energy and Wastewater.

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