To support the development of safe and feasible sludge management strategies, the accumulation rates of sludge and its characteristics were studied in four primary wastewater stabilization ponds (WSPs) in central Mexico (three facultative and one anaerobic). The accumulation rates and distribution of sludge were determined by measuring the thickness of the sludge layer at 8-40 locations through...

The toxic effects of the metals cadmium, zinc and copper on microbial activity in the activated sludge process, are reported. The dissolved metals were added to the process in synthetic wastewater with a COD of 520 mg L. Metal toxicity was determined by the reduction in activity levels of variables such as the specific oxygen uptake rate and mass fraction of active cells present in the reactor....

Leaching of arsenic from brick manufactured from arsenic and iron sludge has been investigated in this study. TCLP result shows that leached metal concentrations are far below the regulated TCLP limits and the quantities of metal leached from sludge are less than those from dried sludge. The results of Atterberg limits tests of moulded sludge-clay mixtures indicated that both plastic index and ...

The present study was performed to assess the effect of the petrochemical sludge application rate on the mutagenic activity (Ames test) of soil and the persistence of mutagenic activity during laboratory soil bioremediation process. Sludge-soil systems were prepared at four different sludge application rates (1.25, 2.5, 5, and 10% w/w). Unamended soil was used as a control. Immediately followin...

Sludge drying reed beds have been used for dewatering and mineralization of sludge since the beginning of the 90s, but their insufficient performances in terms of Dry Matter [DM] content and mineralization of the sludge have made necessary new studies. Therefore, 8 pilots of 2 m2 each and a full-scale plant (13,000 p.e, 8 beds of 470 m2 in operation for 4 years) have been monitored to examine t...

Sludge valorization through methane production is highly limited by the biodegradability of the organic matter. This may be related to the physical and chemical properties of the sludge organic matter that define its bioavailability, its bioaccessibility and its biodegradability. The objective is here to analyze the relationship between the physical state (floc) and the refractory content of a ...

The co-disposal of dewatered sewage sludge and municipal solid waste may cause significant impacts (such as total and differential settlement, slope stability of the waste, and leachability) on landfill operations and the subsurface environment. The objectives of this study were to investigate the co-disposal of dewatered sewage sludge and municipal solid waste with respect to their consolidati...

The enrichment or spiking of sewage sludge with heavy metals for experimental purposes is a fairly widely used, although sometimes controversial, technique. A study was undertaken, using a sequential fractionation scheme, to assess the degree of incorporation of Cu, Ni, and Zn into sewage sludge samples spiked with these metals and incubated for 6 mo. For all three metals, substantial proportio...

Carbonization is a newly developed process that converts sewage sludge to biocoal, a type of solid biomass that can partially substitute for coal during power generation. This study presents an assessment of the environmental effects of various sewage sludge treatment processes, including carbonization, direct landfills, co-incineration with municipal solid waste, and mono-incineration in Taiwa...

Wastewater sludges are used in agriculture as soil amendment and fertilizer, with regard to their organic matter and nutrient content. However, availability of nitrogen and phosphorus from sludge-amended soils and their transfer in runoff may lead to eutrophication of downstream surface water. The aim of this study is to establish and compare the effect of two different sludges on these transfe...