Search results for "sewage sludge"
showing 10 items of 54 documents
Economic sustainability of hydrothermal liquefaction of sewage sludge: From a conceptual analysis to a practical verification
2022
Introduction: Hydrothermal liquefaction (HTL) could be a promising technology to produce biocrude from wet biomass. A conceptual analysis on the HTL of microalgae assisted by the use of solar heat demonstrated that even if microalgae are one of the most productive and investigated feedstock, their high cost hinders the economic sustainability of the process1. To overcome this issue a zero-cost wet waste biomass like sewage sludge (SS) could be adopted with comparable efficiency. Furthermore, the use of a proper catalyst, promoting the in-situ upgrading of the biocrude, still represents a big challenging opportunity for industrial HTL development. Aim: The outcomes of the conceptual analysis…
A software for the integrated design of wastewater treatment plants
1998
Abstract A software package has been developed for automated design of wastewater treatment plants. A user-friendly environment has been implemented to facilitate design tasks, allowing rapid evaluation of different alternatives as well as performing sensitivity analyses. Flexible treatment plant configurations can be established with preliminary, primary, biological and tertiary wastewater treatments, and sludge treatment units. A generalized steady-state model developed for biological processes is also included. The design process includes treatment units sizing, plant layout, hydraulic profile calculation and equipment assignment. The system capabilities for designing new plants and upgr…
Membrane bioreactors sludge: From production to disposal
2020
Abstract This chapter reviews the MBR activated sludge from production to disposal. Starting from sludge characterization, the chapter first presents the features of MBR sludge (morphology and EPS chemical composition), also in terms of differences with the activated sludge from conventional activated sludge plants. Sludge dewaterability is then discussed, focusing on the differences between aerobically and anaerobically digested sludge. An analysis of the costs related to MBR sludge treatment and disposal also is presented in order to provide a framework for a sustainable MBR sludge management.
Assessment of the mutagenic potency of sewage sludges contaminated with polycyclic aromatic hydrocarbons by an Ames sludges for fluctuation assay
2003
9 pages, 1 figure, 6 tables.-- PMID: 14587895 [PubMed].
Eubacteria and archaea communities in seven mesophile anaerobic digester plants in Germany
2015
Background Only a fraction of the microbial species used for anaerobic digestion in biogas production plants are methanogenic archaea. We have analyzed the taxonomic profiles of eubacteria and archaea, a set of chemical key parameters, and biogas production in samples from nine production plants in seven facilities in Thuringia, Germany, including co-digesters, leach-bed, and sewage sludge treatment plants. Reactors were sampled twice, at a 1-week interval, and three biological replicates were taken in each case. Results A complex taxonomic composition was found for both eubacteria and archaea, both of which strongly correlated with digester type. Plant-degrading Firmicutes as well as Bacte…
Fate of PCDD/PCDF during mechanical–biological sludge treatment
2004
Abstract In this preliminary study the seventeen 2,3,7,8-substituted congeners of PCDD/PCDF were analyzed at the inlet and outlet water and for three sewage sludge samples taken from different treatment stages to check behaviours of PCDD/PCDF at a municipal wastewater treatment plant (MWTP) in Poland. At the inlet (untreated sewage) water dominated PCDD congeners, whereas in the outlet (treated water) dominated the PCDF congeners. The octaCDD, 1,2,3,4,6,7,8-heptaCDD/CDF and octaCDF congeners dominated in all of the sludge samples. The total toxicity load gradually increased in the series excess, digested and dewatered sludge and amounted to 12.2, 14.4 and 16.9 ng I-TEQ kg −1 .
Struvite precipitation assessment in anaerobic digestion processes
2008
Struvite precipitation causes important operational problems during the sludge treatment process, especially when EBPR sludge is treated. Predicting struvite formation is critical to be able to design process alternative that best minimises struvite precipitation. With this aim, phosphorus precipitation in an anaerobic digestion pilot plant was studied using experimental data and mass balance analysis. The results obtained showed significant phosphorus precipitation as struvite (58% of the fixed phosphorus) and a low precipitation of calcium phosphates (15%), forming mainly hydroxyapatite (HAP). The rest of the phosphorus fixed in the digester (27%) was attributed to adsorption processes on…
Evaluation of the fuel potential of sewage sludge mixtures with beech sawdust and lignite
2018
Sewage sludge (SS) from municipal wastewater treatment has drawn serious attention of scientists around the world in the attempt to find feasible disposal methods. Therefore, in this work, a solution for valorisation of SS as solid fuel is proposed based on an advanced compositional investigation of SS versus conventional solid fuels, namely, lignite (L) and beech sawdust (BS). A characterisation in terms of proximate analysis and ultimate analysis was performed for the studied materials, both to SS, L, and BS as single fuel and to bi-component mixture formulas of SS and L/BS, in variable proportions of 30:70, 50:50, and 70:30. SS:BS based blends had higher hydrogen (from 4.43 wt. % to 5.14…
The management of sewage sludge: technologies, critical issue and perspectives
2022
The management of sludge produced by urban wastewater treatment plants has long been a problem for plant managers. This is due both to the growing costs for their disposal, and to the possible consequences that incorrect management may have on the performance of the wastewater treatment plant and on the environment. Further difficulties arose following the evolution of the European and national legislations, which regulates the management of sludge and its possible agronomic uses that introduced further checks and restrictions for this use. Several studies have been underway since last decades to reduce the extent of the problem. These focus on alternative objectives being aimed on the one …
Wastewater treatment sludge composting
2023
In recent years, the amount of sewage sludge generated by wastewater treatment plants (WWTPs) has increased due to worldwide population growth and to efficiency of biological treatment processes [1,2]. Sludge is an important source of secondary pollution to aquatic environments and a potential risk to human health; moreover, it represents one of the most important cost items in the functioning of water treatment plants [3–5]. About 60% of the operating costs of secondary wastewater treatment plants in Europe can be associated with the treatment and disposal of products [6]. For this reason, proper sludge management becomes increasingly important, at both national and international level, an…