The evolving challenges of wastewater treatment

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Dan Parry, Head of Sales – Municipal and Industrial at Veolia Water Technologies UK (VWT UK), examines the factors driving change in municipal water treatment today and the issues that will affect the sector in the years to come.

The wastewater sector has faced a host of challenges for some time, including supply resilience, reducing leakage, reducing carbon emissions and reducing consumer costs. None of these issues are quick or easy to resolve, however, the targets for many of these issues have been included in regulator Ofwat’s final decisions from its latest price review (PR19).

Focus on phosphorus

One of the primary wastewater treatment goals for the current asset management period (AMP7), which extends to 2024, is to reduce the impact of phosphorus. The government’s ambitious Water Industry Environment Program (WINEP) includes the implementation of approximately 1,000 new phosphorus (P) permits in final effluents as part of efforts to protect and to improve at least 6,000 km of rivers, bathing waters, shellfish sites and nature conservation sites.

Phosphorus can enter waterways from a variety of sources, including excess fertilizers washed into rivers and discharges from sewage treatment. If large amounts of phosphorus reach rivers and lakes, the water can become too rich in nutrients and trigger algae blooms. This depletes the oxygen in the water, leading to the death of aquatic fauna and preventing sunlight from reaching aquatic plants.

There is no single answer for phosphorus management. However, advances in technology now offer solutions to help water companies achieve these goals in the most cost-effective way.

An important area is to optimize the performance of current assets to increase their efficiency and achieve higher processing levels. Often this will minimize or even negate the need for capital expenditure for a new plant.

The growth of connected technologies has made it easier to monitor and improve the performance of a wastewater treatment plant and the wider wastewater network. Sensors can be installed on all key equipment to collect real-time data on system performance. Together with a specialist, this information can be used to identify improvements that can be made. Additionally, sophisticated algorithm-based optimization, such as that provided by Veolia Water Technologies’ Hubgrade digital management system, can continuously monitor wastewater characteristics to maximize efficiency, reduce operational expenses, and ensure performance remains at an optimal level.

When investment in a new plant is required, there is a range of solutions available to meet the needs of different sites. For example, a highly durable woven fabric filter system is an ideal solution to improve the performance of the existing installation.

For sites requiring additional capacity, a sand-weighted flocculation system can offer high throughput, and solutions from leading vendors can offer a compact footprint, ideal when space is at a premium. These systems can have a footprint up to eight times smaller than lamellar or dissolved air flotation (DAF) clarifiers and up to 50 times smaller than conventional clarification systems. This technology also provides operational flexibility to meet current and future phosphorus removal requirements.

The future challenges of wastewater treatment

Going forward, the challenge for wastewater treatment in the coming years will probably be micropollutants. These are natural or man-made substances that enter the environment and waterways and have known or suspected adverse effects on the environment and human health. Micropollutants are the result of human activity and come from sources such as industrial processes, agriculture, household cleaning, personal care products and pharmaceuticals. They most often enter the environment through the discharge of sewage and flow from land to waterways.

Levels of these micropollutants in water are not widely monitored and the substances are not completely removed by commonly used water treatment processes. Typically, conventional wastewater treatment only removes about 20-40%. Although in the UK the concentration of each of these pollutants in water is generally low, many of these pollutants are known to be toxic or harmful to health even at low concentrations, and the full effects of many others are still under study. Some are known carcinogens, while others are known to cause birth defects, developmental disabilities, or affect fertility and reproductive health. Some of the micropollutants can also cause significant and damaging changes in natural ecosystems.

aerial view of the body of water

While concentrations can be as low as one nanogram per liter of water – the equivalent of a single paracetamol tablet in an Olympic swimming pool – long-term, daily exposure to these pollutants increases the risk of impacts serious on health. In addition, climate change will have an effect, as water shortages could lead to increased concentrations of these substances in drinking water.

There are currently no regulations in place requiring water treatment to address the problems posed by certain micropollutants in the UK or most of Europe. The notable exception is Switzerland where, since January 2016, the Swiss law on water protection sets the target for treatment plants to remove 80% of these pollutants. Funding comes from a waste water tax which equates to approximately CHF 9 per person per year.

As understanding of this water quality issue develops in the coming years, it is likely that action will be taken to address this type of pollution during MPA 8. There are already have proven wastewater treatment solutions available that can remove these substances. For example, our Actiflo® Carb technology combines coagulation, flocculation and lamellar settling stages with an additional Powdered Activated Carbon (PAC) contact tank to absorb pollutants. The standard Actiflo® system has been used for the treatment of industrial and municipal wastewater for more than 25 years; but with the addition of PAC technology it has been used in the UK to remove various pesticidal micropollutants, such as metaldehyde.

Whether to meet current requirements or to sustain a plant and its processes, a partnership with a water treatment specialist is always recommended. Leading vendors can offer end-to-end project support, including existing plant assessment, design services, engineering support with ongoing service and maintenance.

Wastewater treatment requirements continue to evolve as the industry strives to limit the impact of human activity on the environment and protect the integrity of our drinking water supplies. With the support of manufacturers who can offer a holistic approach and a range of solutions, water companies can ensure that they achieve these goals in a cost-effective way.

Photos of Bluewater Sweden and Ivan Bandura

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