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The way excess sludge must be disposed of is a key factor in the choice of the appropriate phosphorus removal technique at municipal wastewater treatment plants. In Europe the ongoing trend of tightening the sludge spreading rules called for a serious reduction of its agricultural utilisation and the expansion of the (co-)incineration disposal route, which led to a shift towards more sophisticated sludge handling techniques. This paper illustrates the impact of different sludge handling techniques on the performance of chemical and enhanced biological phosphorus removal at municipal WWTPs. The main conclusion is that although enhanced biological phosphorus removal is particularly sensitive to the problem of return liquors from sludge treatment processes indirect dewatering and anaerobic stabilisation cannot be discarded altogether when considering its implementation. [ABSTRACT FROM AUTHOR]

Reports on the use of a pilot study and dynamic modelling to optimize the dimensions of different tanks during the renovation of the Wastewater Treatment Plant in Bruges, Belgium. Hydraulic dimensions; Pilot plant; Key points of the dynamic model; Storm water treatment; Biological treatment; Budget.

Recently collected dietary exposure data on mineral oil saturated (MOSH) and aromatic (MOAH) hydrocarbons were used to evaluate the risks associated with exposure to mineral oil through food for the Belgian population. For MOSH, the no observed adverse effect level (NOAEL) value of 19 mg kg -1 bw day -1 based on the hepatic inflammation-associated granulomas found in a 90-day oral study in F-344 rats was used as point of departure (PoD). Due to existing toxicological uncertainties, the margin of exposure (MOE) approach was applied. In all investigated scenarios, the MOE values were well above 100, indicating that there is no direct health concern related to MOSH exposure for the Belgian population. Nevertheless, more appropriate risk assessment approaches for MOSH based on adequate PoD are needed. For dietary exposure to MOAH, which are potentially genotoxic and carcinogenic, no MOE values could be calculated due to the lack of adequate dose-response carcinogenicity data. In two investigated worst-case scenarios, a health concern related to MOAH exposure could not be excluded, highlighting that more data are needed to perform an adequate risk assessment. The possibility to use in vitro bioassays to collect such additional toxicological information for MOAH present in food samples was also investigated., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The provision of reliable treatment has always been a priority in sanitary engineering. However, there is an ever-increasing pressure to meet desirable standards at reduced costs. This paper sets out a methodology to enhance the likelihood of a satisfactory allocation of the resources while providing reliable treatment. The procedure was gradually developed to optimise the massive capital investment of the Flemish Government to comply with the effluent standards set in the EU Directive 271/91. The methodology makes an extended use of dynamic modelling. To facilitate the identification and estimation of the uncertainty, a probabilistic Monte Carlo engine is coupled to the dynamic models. In doing so this approach provides a way of explicitly incorporating uncertainty and variability in the process analysis. The procedure is examined in an upgrade of a conventional WWTP towards stricter effluent norms on nutrients. The results suggest that the procedure can support the decision-making process under uncertainty conditions and enhance the likelihood of meeting effluent standards not entailing above-normal capital investments. The analysis led to reducing the capital investment by 43%, producing savings of more than 1.2 million Euros.