WET News

APRIL 2014 WET NEWS 25 Odour control is much higher on water companies' agen- das as residents become less tolerant of nuisance odours The challenge: Odour control no longer an aerthought W ith ever tightening en- vironmental pollution legislation, the impact on odour control in waste water treatment facilities can be huge. And in the modern world of wastewater treatment, control of odours has moved from an af- terthought to a primary design consideration. As development encroaches on facilities and residents become less tolerant of INSIGHT WATER TREATMENT The Q45S monitor utilises a Wet H 2 S sensor that eliminates water vapour bleeding nuisance odours, wastewater professionals have become more motivated to look for new reliable and effective methods to address odour as a priority. Odours emitted by sewage treatment are typically an indi- cation of an anaerobic condition that occurs when there is lim- ited surface area for oxygen to penetrate. In this anaerobic state, microbes present in the wastewater have no dissolved oxygen available for respiration and this allows anaerobic microbes to thrive and grow. Regulators have a duty under the Environmental Protection Act 1990 (EPA 90) and Environ- mental Permitting Regulations 2010 (EPR 2010) to investigate cases where odour may be causing statutory nuisance or breaching the conditions of an EPR Permit. Offenders are taken to court and fined a substantial amount of money and failure to comply with a permit could ultimately lead to the closure of site operations. Whilst the closure of a wastewater treatment works would be impracticable, a local authority can issue an Abate- ment Notice to bring about com- pliance within a given timeframe. With the attention paid to odour control increasing, the number of technologies avail- able in the marketplace has expanded too A solution: Technologies not to be sniffed at E ach wastewater treatment site faces real challenges when it comes to balancing the expense of running the plant with the cost of installing appro- priate sensors to tackle the issue of odour control. Smaller air cleaning plants may only be worth £30,000, yet some H 2 S monitors can cost up to £20,000, which is just not viable. However, there are a number of technolo- gies available at varying costs, meaning there are sensors avail- able for all budgets and applica- tions. Chemical scrubbing is normally used for cleaning large air volumes on sewage treat- ment plants with an airflow rate of between 5,000-10,000m 3 / hour. These scrubbers can achieve high efficiencies of up to 99.95%. A typical system treat- ing air with an average of 25ppm H 2 S at the inlet at 25,000m 3 hour would cost around £175,000. Used for treating small air- flows from wet wells and pump- ing stations, dry media carbon filters are used for smaller vol- umes of between 200-10,000m 3 / hour and sometimes as a pol- isher a–er chemical treatment. Carbon filters also achieve high efficiencies up to 99.5%. These systems treat smaller volumes and can be installed for around £30,000. Carbon dry media sen- sors effectively monitor odour control at low outlets, are upgradeable for low outlet odour and have regenerable carbon. Bio scrubbers sit somewhere in the middle. Generally used for treating media airflow rate vol- umes of up to 10,000m 3 /hour and high loadings from inlet works and sludge processing, they achieve efficiencies of up to 99.5% with systems costing around £50,000. Alternatively, specialist electrochemical sensor manufacturers offer cost-effective breakthrough monitoring at a cost of under £2,000 installed. Systems like the ATi Q45S Wet Sensor for Scrubbers provide a lower priced alternative to expen- sive tape and film based H 2 S monitors and utilise a sensor designed to operate in condens- ing gas streams without the water vapour blinding, which can be typical of standard sulphide sensors. The key advantage of the new Q45S monitor is that it utilises a Wet H 2 S sensor that eliminates water vapour bleeding for accu- rate and cost-effective H 2 S moni- toring, where condensing humid- ity conditions are normal. In normal use an outlet moni- tor will read 0.05ppm to 0.200ppm. At these levels the scrubber is working effectively but in the event of a break- through, the reading will rise rap- idly and the in-built alarms are activated before the legislative limit is reached. Historically, sew- age treatment plants have o–en struggled to justify the expense of installing H2S monitors that can cost up to 80% of the value of smaller plants. However, there is now a monitor available to suit all budgets and applications. At £2,000 installed, this repre- sents around 6% of the value of even the smallest plants, it is a cost effective solution to avoiding expensive breaches of regula- tions and resident complaints. • Total ammonia • Free ammonia • Chloramine • Final effluent monitor • Chloramination control • Inlet monitoring w w w. a t i u k . c o m F O R WA S T E WAT E R A N D P O TA B L E WAT E R A P P L I C AT I O N S Tel: 0800 8046 062 sales@atiuk.com On Line Ammonia monitor F O R WA S T E WAT E R A N D P O TA B L E WAT E R A P P L I C AT I O N S Very low running costs Simple electrochemical sensing technique Ammonia Advert (WITH QR CODE):ATi 27/9/12 15:18 Page 1 01403 221000 Performance guaranteed systems designed for cost effective operation Odour Control Specialists www.ergapc.co.uk info@ergapc co.uk

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