Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | augusT 2017 | 9 and running costs and/ or the need for hazardous chemicals. However, biological treatment represents an efficient, cost- effective and natural means of odour mitigation in the wastewater treatment plant. It is doubtless that treatment with suitable bacterial strains can greatly reduce problems associated with unpleasant odours. In the same way that they reduce BOD, COD and TSS, correctly selected bacteria will break down organic matter at source, preventing the formation of unpleasant odours. As with other contaminants it is important that they possess the correct metabolic abilities in order to degrade these molecules and Biological Preparations supplies bacterial consortia with good all-round abilities, breaking down a wide range of organic compounds, as well as specific species and strains to target the odour-causing compounds mentioned above. Modifying the conditions in the treatment plant, along with bacterial dosing, is another extremely successful strategy. The production of most odour- causing compounds is associated with anaerobic (septic) environments and hydrogen sulphide is a classic example. Under septic conditions where there is no dissolved oxygen available, sulphate- reducing bacteria will use sulphates commonly found in municipal wastewater as a source of oxygen for respiration, resulting in the production of hydrogen sulphide. This noxious gas is well known for its "rotten egg" odour and represents a real hazard to plant workers as well as causing significant corrosion of metal surfaces. Aeration and/ or increased circulation will certainly alleviate such problems but where this is not practical, Biological Preparations supplies a nutrient that provides an alternative source of oxygen for respiration, which is used by resident and dosed bacteria in preference to sulphate. Whilst this nutrient is kept in excess no further hydrogen sulphide will be produced and given the common prerequisite of septic conditions for odour formation, this method will oŒen solve other odour problems as well. We also employ other technologies that can be used in combination with the approaches above or even as stand- alone solutions, such as certain odour- absorbing plant extracts and naturally- derived odour-binding agents that produce immediate results whilst altered conditions and new biological processes are established. Biological Preparations experts can advise on the correct solution(s) and suitable methods of treatment to alleviate the odour problems encountered at a particular site. SPONSORED BY Dr. John Lear TechnicaL DirecTor BioLogicaL PreParaTions LTD. Biological odour control in wastewater treatment plants When odour issues threaten to impact on the operations and reputation of wastewater utilities, bacterial treatments can hold the answer T he generation of unpleasant odours can be a significant problem for wastewater treatment plants, particularly during the warmer summer months. They create an unpleasant working environment or health and safety issue for plant workers and as odours driŒ into the surrounding area, result in public nuisance and damage to a company's reputation in the local community. Odours in the wastewater treatment plant are caused by a variety of compounds, mainly: 1) reduced sulphur compounds, e.g. hydrogen sulphide, mercaptans, organic sulphides; 2) nitrogen compounds, e.g. ammonia, amines; 3) volatile fatty acids, e.g. formic acid, butyric acid; 4) aldehydes and ketones. Simple control methods such as masking or containment may be insufficient and more complex treatment systems such as thermal or chemical oxidation are associated with high set-up planning is no longer appropriate. The need to change the approach that the industry takes to water resources in the long term, and to ensure that there is a resilient supply for future generations is, I can safely say, now firmly on the agenda across the water industry. The AMP6 regulatory cycle is beginning to show a step change in the way in which water resources are planned and managed in the UK, and in particular, whether there are better ways to allow for uncertainty and risk in water resource and drought planning. I think this is best demonstrated by four separate but very much related initiatives that can feed into the debate on policy and strategy moving forward: 1) Water UK – Water resources long-term planning framework 2015- 2065 (published September 2016); 2) UKWIR – Methodologies for WRMP19 (published in 2016 and included in Environment Agency Water Resource Planning Guideline for WRMP19); 3) Joint UK Research Council MaRIUS project (Managing the Risks, Impacts and Uncertainties of drought and water Scarcity (on-going); 4) UKWIR - RG06: Resilience – Performance measures, costs and stakeholder communication (awaiting publication); and 5) Regional and individual water company initiatives – for example Water Resources in the South East (WRSE), Water Resources East (WRE). The Water UK project has brought together the outputs from recent work and methodologies and has the potential to mark a clear change in the UK's approach to water resource planning. The momentum that has been generated by that project combined with the recent UKWIR projects needs to be maintained in statutory plans and used to inform the work of the National Infrastructure Commission (NIC). I think that AMP6 is continuing to provide an excellent opportunity for a fresh focus on many aspects of water resource and drought planning. Ofwat is expected to include resilience-based performance commitments in its PR19 methodology. The Water UK project and the UKWIR projects have brought together the outputs from recent work and methodologies and has the potential to mark a clear change in the UK's approach to water resource planning. What is required is the momentum that has been generated by the project is maintained in statutory plans and is used to inform the work of the National Infrastructure Commission. And for me, we need the discussion around weather extremes to be ongoing and not just brought to focus during a heatwave. The Talk: opinion