In order to enhance mechanical dewatering, conditioning polymers are used to flocculate sewage sludge. These polymers modify floc structure, which has an impact on dewatering efficiency. However, fundamental aspects of those processes are incompletely understood, particularly the way that flocs are structurally organized and how this may relate to their mechanical and dewatering properties. Thu...

abstract a study was conducted to evaluate the effect of incubation time, sewage sludge and clay content on the distribution of nickel and cadmium in different fractions of selected calcareous soils. to meet this purpose, an experiment with two different soils (4 and 30 percent caco3), two different textures (8 and 40 percent clay), two levels of nickel (0 and 100 mg.kg-1), two levels of cadmiu...

The aim of the study was to define the relationship between the concentration of PAHs in sewage sludge at a particular location and their amount in various plant materials growing on it. The credibility of the results is enhanced by the fact that sewage sludge from two separate sewage-treatment plants were selected for their influence on the content of PAHs in three plant species growing on the...

Sewage sludge was disposed of in Liverpool Bay for over 100 years. Annual amounts increased from 0.5 million tonnes per annum in 1900 to approximately 2 million tonnes per annum by 1995. Macrofauna and a suite of environmental variables were collected at a station adjacent to, and a reference station distant from, the disposal site over 13 years, spanning a pre- (1990-1998) and post- (1999-2003...

Since potassium is essential for plant nutrition, should this element be deficient in sewage sludge used for plant fertilization supplementary mineral potassium fertilization is necessary. The aim of the present study has been to evaluate the effect of fertilization with organic materials on maize yield, its potassium concentrations and the content of bioavailable forms of potassium in soil of ...

Heavy metals in high concentrations can cause health and environmental damage. Nanosilver is an emerging heavy metal which has a bright future of use in many applications. Here we report on the levels of silver and other heavy metals in municipal sewage sludge. Five towns in Limpopo province of South Africa were selected and the sludge from their wastewater treatment plants (WWTPs) was collecte...

This paper reviews the sources, bioavailability and fate of heavy metals and organic contaminants in compost manure and in soils of which the manure is applied. The toxicity of heavy metals and organic compounds in soil of which would have come from applied compost is also discussed. Type of materials, their background and where collected for use in composting contribute to the sources of heavy...

Sewage sludge from municipal wastewater treatment is used in agriculture as a nutrient source and to aid in moisture retention. To examine the potential impact of sludge-amended soil on exposures to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from plant and animal foods, we conducted a review of published empirical data from international sources. Levels of PCDD/F in municipal...

A field experiment was carried out to study the effect of application rates of sewage sludge and mineral nitrogen and phosphate fertilizers on As, Ba, Cd, Cr, Cu, Ni, Pb, Se, and Zn concentration in soil, cane plant, and first ratoon (residual effect) in a Typic Hapludult soil. To allow an analysis by means of response surface modeling, four rates of sewage sludge (0, 3.6, 7.2 and 10.8 t ha(-1)...

The sewage sludge production in Egypt is rapidly increasing resulting from the continuous increase of population, urban planning and industrial developments. This sludge needs to be adequately treated and environmentally managed to reduce the negative impacts of its application or disposal. Therefore, the main currently pressing needs are to find/develop more efficient, economical and sustainab...