ENVIRONMENTAL NEWS
Bassenthwaite Lake, Keswick, UK an EA Nutrient Neutrality site
Nutrient Neutrality requires package treatment plant upgrade
With nutrient neutrality requirements being enforced at off-mains properties in areas of England, homeowners need to understand the benefits of non- chemical package treatment plants, writes Andrew Baird, technical director at WCS Environmental Engineering.
Nutrient neutrality planning requirements are being put in place in specific parts of England to protect sensitive waters and marine life. For domestic homeowners and developers using package treatment plants (PTPs), this poses new considerations around both planning and treatment processes.
Nutrient neutrality is crucial for protecting water bodies from nutrient pollution, which can cause eutrophication, algal blooms, and oxygen depletion - harming aquatic ecosystems and biodiversity.
Nutrient neutrality emerged in June 2019, when government advisor Natural England began issuing advice to Local Planning Authorities (LPAs) with protected bodies of waters to only grant planning permission to properties and developments proven to be nutrient neutral.
The guidance applies to 74 areas with surface water impacted by high levels of contaminants, mainly phosphate and nitrate. These are present in treated wastewater discharged to watercourses in the final stage of the water treatment process, which can be harmful to water environments and ecosystems if above a certain threshold.
Nutrient neutrality is a means of 38
ensuring that the development of new homes or changes in the way existing homes are run or occupied, that would result in a net increase in population served by a wastewater system, do not add to the nutrient burden of protected waters.
By ensuring new developments or existing properties do not increase nutrient levels, the requirements help maintain water quality, support sustainable development, preserve the health of sensitive environments, and prevent long-term environmental degradation.
Demonstrate removal plan
In the 74 affected regions determined by Natural England, developers and property owners must prove wastewater treatment schemes will be nutrient neutral by demonstrating in planning applications how the full amount of anticipated nutrients will be removed or offset.
For properties with off-mains drainage, onsite PTPs represent a significant factor in the neutrality equation in developments of varying sizes. As a sustainable water recycling specialist, WCSEE continues to see an increase in enquiries for its biological compact PTPs, which can remove up to 80% of nutrients found in wastewater. Whilst the standard PTP can achieve 52% nutrient removal further treatment is required to hit the 80% figure.
Chemical risk Low-cost chemical dosing PTPs are
| December 2024 |
draintraderltd.com
Andrew Baird, technical director at WCS Environmental Engineering
being offered as a solution to remove phosphates in off-mains drainage areas by some suppliers. While chemicals are appropriate in many regulated water utility applications with sophisticated dosing equipment and/or low population densities, they are not suitable for smaller domestic off-mains drainage.
This is because in England the volume of receiving waters tends to be low, and population densities are high (up to 276 per square kilometre), so a chemical solution may deliver worse environmental outcomes than the problem it seeks to address. This is especially true in counties such as Devon and Cornwall which have the highest density of installed septic tanks and PTPs in England.
For comparison, the countries of Norway and Canada do allow chemical solutions for domestic wastewater treatment as standard, but the population densities are far lower (15 and four people per square kilometre respectfully).
Additionally, in many countries, there
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