Feature: The evolving challenges in wastewater treatment

Dan Parry, Head of Sales – Municipal and Industrial at Veolia Water Technologies UK (VWT UK), looks at the factors currently driving changes in municipal water treatment and the issues that will affect the sector in the coming years.

The wastewater sector has been facing a multitude of challenges for some time, these include supply resilience, minimising leaks, reducing carbon emissions and lowering costs to the consumer. None of these are quick or easy to address, however, targets for many of these issues were included in the regulator Ofwat’s final determinations from its latest Price Review (PR19).

A focus on phosphorus

One of the key wastewater treatment goals for the current Asset Management Period (AMP7), which runs up to 2024, is reducing the impact of phosphorus. The Government’s ambitious Water Industry National Environment Programme (WINEP) includes the implementation of approximately 1000 new final effluent phosphorus (P) consents as part of efforts to protect and improve at least 6000 km of watercourses, bathing waters, shellfish sites and nature conservation sites.

Phosphorus can enter watercourses from a variety of sources including excess fertilisers being washed into rivers and discharges from sewage treatment. If large quantities of phosphorus reach rivers and lakes it can cause the water to become too nutrient-rich and trigger algae blooms. This depletes the oxygen in the water, resulting in the death of aquatic wildlife as well as blocking sunlight from reaching water-based plants.

There is no one-size-fits-all answer for managing phosphorus. However, advances in technology now offer solutions to help water companies meet these targets in the most cost-effective way.

One important area is optimising the performance of current assets to increase their effectiveness and achieve higher levels of treatment. Often this will minimise or even negate the need for capital expenditure on 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 pieces of equipment to collect real-time data about the system’s performance. Working with a specialist, this information can be used to identify improvements that can be made. In addition, sophisticated algorithm-based optimisation, such as that provided by Veolia Water Technologies’ Hubgrade digital management system, can constantly monitor the wastewater characteristics to maximise efficiency, reduce operational expenditure and ensure the performance remains at an optimal level.

Where investment in a new plant is required, there are a range of solutions available to meet the needs of different sites. For example, a highly durable woven cloth filter system is an ideal solution for enhancing the performance of the existing plant.

For sites that require additional capacity, a sand ballasted flocculation system can offer a high flow rate, and solutions from leading suppliers can offer a compact footprint, ideal where space is restricted. These systems can have a footprint up to eight times smaller than lamella or dissolved air flotation (DAF) clarifiers and up to 50 times smaller than conventional clarification systems. This technology also offers operational flexibility to meet current and future P removal requirements.

Future issues in wastewater treatment

Looking ahead, the challenge for wastewater treatment in the coming years is likely to be micropollutants. These are natural or synthetic substances that enter the environment and watercourses and have known or suspected adverse ecological and human health effects. 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 commonly enter the environment through wastewater discharge and run off from land into watercourses.

The levels of these micropollutants in water are not widely monitored and the substances are not completely removed by commonly operated water treatment processes. Typically, conventional wastewater treatment only removes around 20 to 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 damaging to health even at low concentrations and the full effects of many others are still being studied. Some are recognised carcinogens, while others are known to cause birth defects, developmental disorders or affect fertility and reproductive health. Some of the micropollutants can also cause significant and damaging changes in natural ecosystems.

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

There are currently no regulations in place requiring water treatment to tackle the issues posed by some micropollutants in the UK or across most of Europe. The notable exception is Switzerland, where, since January 2016, the Swiss Waters Protection Act has set the goal for wastewater treatment plants to eliminate 80% of these pollutants. The funding for this comes from a wastewater tax that equates to approximately 9 CHF per person, per year.

As the understanding of this water quality issue grows in the coming years it is likely that measures will be brought in to tackle this type of pollution during AMP 8. There are already tried and tested wastewater treatment solutions available that can remove these substances. For example, our Actiflo® Carb technology combines coagulation, flocculation and lamella settlement stages with an additional Powdered Activated Carbon (PAC) contact tank to absorb the pollutants. The standard Actiflo® system has been used for industrial and municipal wastewater treatment for over 25 years; but with the addition of PAC technology, it has been used in the UK to remove various pesticide micropollutants, such as metaldehyde.

Whether it is to address current requirements or for future-proofing a plant and its processes, partnering with a water treatment specialist is always recommended. Leading providers can offer end to end project support including assessment of the existing plant, design services, technical assistance with ongoing service and maintenance.

Wastewater treatment requirements continue to evolve as the sector strives to limit the impact of human activity on the environment as well as 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 they meet these targets in a cost-effective way.

Photos by Bluewater Sweden and Ivan Bandura