Practical determination of the rheological behavior of pasty biosolids

International audienceIn this paper, we demonstrate that the rheological behavior of pasty sewage sludges, regardless of origin, treatment or composition, follows a Herschel-Bulkley model. The yield stress and solid volume fraction are found to be the only two distinctive rheological characteristics of these materials. By scaling the shear rate and the shear stress with two parameters depending only on the yield stress and the solid fraction, the flow curves of 48 pasty sludges all fall along a unique dimensionless master curve. This result may be used in practice to determine, from simple, independent measurements, the rheological behavior of any pasty sludge : the yield stress can be measured with the help of the "slump test" and the solid concentration determined from the organic and mineral matter contents. The results obtained with this technique are in very good agreement with those obtained direct rheometry

Regulatory Framework in Sludge Management: Examples from Around the World

Treatment and disposal/beneficial use are the most important aspects of municipal sludge management. Particularly, the application guidelines and limit values for treatment systems and the major disposal routes including landfilling, land application and incineration are covered in the legislations. This study aims to review the legislations about municipal sludge treatment and disposal from different counties such as Turkey, USA, EU, Canada and South Africa. Evaluations show that the current legislations place a greater emphasis on the beneficial use of sludge, rather than the mere disposal. The specifics of regulations related to combustion changes between different countries such that in some countries separate regulation for sludge combustion is implemented, whereas in others sludge is not specifically mentioned but included among the big group of wastes to be combusted. Similarly, some countries have particular regulations for landfilling of sludge, whereas the others consider sludge within the greater category of biodegradable wastes together with the organic fraction of solid wastes. This study compares and contrasts these issues and current legislations of the aforementioned countries

Current Situation and Future Perspectives in Municipal Wastewater Treatment and Sludge Management in Turkey

Appropriate management of wastewater and sludge requires several systems. One of these systems is the collection of data about generation rates and characteristics of sludge. This paper aims to summarize the work done as a part of a threeyear project requested by the Turkish Ministry of Environment and Urbanization. Efforts involved preparation and evaluation of a detailed questionnaire for currently operated wastewater treatment plants (INWTPs) in Turkey, collection and confirmation of information from visits to large scale plants, calculation of theoretical sludge generation rates from data provided, and its comparison to reported sludge amounts