Project Appreciation and Objectives
Odours at sewage treatment works are a significant cause for complaint and continued investment in mitigating measures will be required over the next decade. Although it is possible to reduce odours by good housekeeping and best practice, certain processes, especially at large works, will require covers and odour abatement equipment if complaints are to be reduced.
A major factor in designing and operating covers and equipment is the emission rate of odour from the covered process. The rate of ventilation is a crucial controlling variable: too much may generate odour unnecessarily and require very large plant; too little and the poor quality of the air may increase operating costs due to explosion hazard, enclosed space working and increased corrosion.
This project will define the relationship between ventilation rate and foul air quality to enable the balance between asset lifetime cost and the efficiency of abatement to be optimised.
Benefits to Clients
- Optimal ventilation rates for improved design and operation of covered odour emitting processes.
- Including full costs will strengthen the cost-benefit-assessment of odour abatement schemes and submissions to Ofwat.
- Published cost data for process covers, air extraction and ducting.
- How asset life of a covered process varies with humidity and hydrogen sulphide
- Costs of explosive atmosphere control and equipment; of enclosed space operation; other factors consequent on enclosing e.g. poor visibility of scrapers.
- Model the effect of ventilation rates on the concentration of odours within enclosures. Produce ranges of curves relating ventilation rate to air quality from different types of source. Quantify the affect of ventilation on the amount of odour extracted and the cost and effectiveness of treating the odorous air.
- Use a series of cover and treat scenarios to further develop the relationships and show the effect of ventilation rates on full-life costs.
- A "ready reckoner" to optimise covering, ventilation rates and abatement equipment.
- Report detailing the methodologies identified to quantify the effect of ventilation on odour emissions and effect on abatement equipment.
- Familiarisation workshop on how to use the report and ready reckoner.
WRc has been active in the area of odour control for twenty years. Recent work has included:
- a study into odour from sewage treatment for DEFRA,
- the preparation of a Guidebook on BPM for Odour Control for UKWIR,
- a study for the 'Preparation of a Best Available Techniques Document for Odour Control' also for UKWIR,
- Portfolio collaborative research into odour from sludge and into the use of additives for odour control (CP149 & 295).