Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | AUGUST 2018 | 31 The Knowledge odour control Getting to Grips with… biological odour control Biological products represent an alternative solution to tackle odour issues in the wastewater and water treatment industry, writes Dr Chris Charles BY DR CHRIS CHARLES, WATER AND WASTEWATER TREATMENT SPECIALIST, GENESIS BIOSCIENCES Q. What are the most common causes of odour problems in wastewater treat- ment? A: It's no surprise that a facility dealing with wastewater generated by a local population will have a distinct odour. Complex organic materials from a multitude of sources – domestic, trade or industrial – combine to produce effluent capable of generating an array of malodours. From rotting eggs and cabbage to eye-stinging ammonia, a wastewater plant delivers an array of scents which o en cause discomfort to the local community. The common causes of these odours are generally related to the following: sulphur containing compounds such as hydrogen sulphide and mercaptans (responsible for rotten egg smell), ammonia and amines (fishy smells), ketones and aldehydes (sickly sweet) and volatile organic compounds (vinegar and off- milk odours). Q&A Q: How are these noxious compounds generated? A: In zones low and deplete in oxygen, microbes capable of anaerobic metabolism will proliferate. These microorganisms undertake the hydrolysis and fermentation of organic molecules such as lipids, proteins and polysaccharides and degrade them to smaller compounds such as acetic acid or propionic acid (vinegar and body odour smells.) This type of metabolism subsequently drives down both local pH and redox potential. These conditions, coupled with the end products of fermentation, favour both gaseous sulphide release (due to acidic conditions) and sulphide production, which is carried out by the sulphate-reducing bacteria. These bacteria are found in many environments and persist even when sulphate is not available for use. They generate energy by coupling the oxidation of organic matter to the reduction of sulphate which acts as an electron acceptor.