Sewage Sludge Treatment and Involvement of Microbes

The tropical regions have specific problems associated with high pathogenic density in the sewage sludge. The aim of this study was to select an adequate sludge stabilization and valorization system comparing the performance of four technologies: anaerobic stabilization without heating, aerobic stabilization, alkaline treatment with lime and aerobic composting. The study was performed in a pilot plant which was built and operated during six months. The main problem for the beneficial use of the sludge was its pathogenicity. All the systems allowed obtaining stabilized products which met the bacteriological criteria for some kind of use. The compost and the alkalinized sludge were bacteriologically safe for use without restrictions in accordance with the Mexican regulations. The accomplishment of the parasitological criteria for use was however impossible with the anaerobic and with the aerobic systems. The compost obtained at 55-60°C with 25d aeration time and the alkaline sludge fulfill the criteria established by for forest and agriculture use and for soil conditioning. The composting could reach the requirements for unrestricted use when operated at temperatures 65-70°C during 45 days which makes it the most adequate sludge treatment system for hot climate regions.

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Treatment and Quality of Sewage Sludge in Germany - Results of a Survey

Water Practice & Technology ◽

10.2166/wpt.2007.020 ◽

2007 ◽

Vol 2 (1) ◽

Cited By ~ 2

Author(s):

A. Meda ◽

C. Schaum ◽

M. Wagner ◽

P. Cornel ◽

A. Durth

Keyword(s):

Sewage Sludge ◽

Treatment Process ◽

Wastewater Treatment Plants ◽

Current Status ◽

Sludge Treatment ◽

Sewage Sludge Treatment ◽

Treatment And Disposal ◽

German Association ◽

Entire Treatment

TIn 2004, the German Association for Wastewater, Water and Waste (DWA) carried out a survey about the current status of sewage sludge treatment and disposal in Germany. The study covered about one third of the wastewater treatment plants and about two thirds of the entire treatment capacity (expressed in population equivalents) in Germany. This provides an up-to-date and representative database. The paper presents the most important results regarding sludge treatment, process engineering, current disposal paths and sewage sludge quality.

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Sewage Sludge Treatment by Hydrothermal Carbonization: Feasibility Study for Sustainable Nutrient Recovery and Fuel Production

Energies ◽

10.3390/en14092697 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2697

Author(s):

Gabriel Gerner ◽

Luca Meyer ◽

Rahel Wanner ◽

Thomas Keller ◽

Rolf Krebs

Keyword(s):

Liquid Phase ◽

Sewage Sludge ◽

Hydrothermal Carbonization ◽

Economic Feasibility ◽

Phosphorus Recovery ◽

High Yield ◽

Nutrient Recovery ◽

Waste Biomass ◽

Sludge Treatment ◽

Sewage Sludge Treatment

Phosphorus recovery from waste biomass is becoming increasingly important, given that phosphorus is an exhaustible non-renewable resource. For the recovery of plant nutrients and production of climate-neutral fuel from wet waste streams, hydrothermal carbonization (HTC) has been suggested as a promising technology. In this study, digested sewage sludge (DSS) was used as waste material for phosphorus and nitrogen recovery. HTC was conducted at 200 °C for 4 h, followed by phosphorus stripping (PS) or leaching (PL) at room temperature. The results showed that for PS and PL around 84% and 71% of phosphorus, as well as 53% and 54% of nitrogen, respectively, could be recovered in the liquid phase (process water and/or extract). Heavy metals were mainly transferred to the hydrochar and only <1 ppm of Cd and 21–43 ppm of Zn were found to be in the liquid phase of the acid treatments. According to the economic feasibility calculation, the HTC-treatment per dry ton DSS with an industrial-scale plant would cost around 608 USD. Between 349–406 kg of sulfuric acid are required per dry ton DSS to achieve a high yield in phosphorus recovery, which causes additional costs of 96–118 USD. Compared to current sewage sludge treatment costs in Switzerland, which range between 669 USD and 1173 USD, HTC can be an economically feasible process for DSS treatment and nutrient recovery.

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Scenario Analysis for Selecting Sewage Sludge-to-Energy/Matter Recovery Processes

Energies ◽

10.3390/en14020276 ◽

2021 ◽

Vol 14 (2) ◽

pp. 276

Author(s):

Francesco Facchini ◽

Giovanni Mummolo ◽

Micaela Vitti

Keyword(s):

Sewage Sludge ◽

Scenario Analysis ◽

Value Chain ◽

Circular Economy ◽

Solid Material ◽

Sludge Treatment ◽

Sewage Sludges ◽

Recovery Processes ◽

Sewage Sludge Treatment ◽

New Perspective

The sewage sludges are the byproducts of the wastewater treatment. The new perspective of the wastewater value chain points to a sustainable circular economy approach, where the residual solid material produced by sewage sludge treatments is a resource rather than a waste. A sewage sludge treatment system consists of five main phases; each of them can be performed by different alternative processes. Each process is characterized by its capability to recover energy and/or matter. In this paper, a state of the art of the sludge-to-energy and sludge-to-matter treatments is provided. Then, a scenario analysis is developed to identify suitable sewage sludge treatments plants that best fit the quality and flowrate of sewage sludge to be processed while meeting technological and economic constraints. Based on the scientific literature findings and experts’ opinions, the authors identify a set of reference initial scenarios and the corresponding best treatments’ selection for configuring sewage sludge treatment plants. The scenario analysis reveals a useful reference technical framework when circular economy goals are pursued. The results achieved in all scenarios ensure the potential recovery of matter and/or energy from sewage sludges processes.

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