Odours from sludge account for over 50% of significant odour problems in the water industry. Odours that come directly from sludge processing can often be abated by enclose and treat options, although at substantial cost. Sludge liquors are highly odorous and raise the risk of unacceptable emissions when returned for treatment. Odours from sludge products during transfer, storage and particularly during recycling to agriculture, are of increasing significance.
Physical treatment processes, such as dewatering, may transfer odours between the three phases, (air, liquid and solid(cake)). How this occurs was not well understood and a better understanding has enabled cost reduction and/or odour minimisation in final products.
High shear processes lead to enhanced odour in the final product. In the short term this enhanced mass transfer leads to volatilisation and in the long term due to release of putrescible material into solution enhancing biological activity and odour production.
Improved techniques for quantifying and predicting emission rates were identified together with their causative mechanisms. For example, agitating sludge cake leads to enormous emission rates, a particular problem during land application. The research looked at how emissions can be reduced by using improved handling techniques.
- Reduced risk and PR implications of generating odour nuisance at sewage treatment works.
- Reduced odour nuisance during application of sludge products to land, hence supporting this valuable sludge outlet
- Decreased odour abatement capital and/or operating costs.