digestate Articles
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Effect of trace metals on halophilic and mixed cultures in anaerobic treatment
Abstract: Trace metals are known to stimulate the activity of anaerobic methanogenic bacteria involved in the degradation of organic matter. The objective of this research was to investigate the effect of three trace metals, iron, nickel and cobalt on the activity of halophilic methanogens, digester sludge and a mixed culture of halophilic bacteria and digester sludge, at various salt ...
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Enhancement of the conventional anaerobic digestion of sludge: comparison of four different strategies
Anaerobic digestion (AD) is the preferred option to stabilize sludge. However, the rate limiting step of solids hydrolysis makes it worth modifing the conventional mesophilic AD in order to increase the performance of the digester. The main strategies are to introduce a hydrolysis pre-treatment, or to modify the digestion temperature. Among the different pre-treatment alternatives, the thermal ...
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The influence of temperature and SRT on high-solid digestion of municipal sewage sludge
The influence of temperature and solids retention time (SRT) on high-solid digestion of municipal sewage sludge was investigated in laboratory-scale reactors. Digestion with high-solid concentration reduces the required digestion volume and is advantageous for urban areas. The experimental conditions comprised total suspended solids (TSS) in digested sludge between 4.0 and 4.6%, temperatures ...
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Hygienization of sludge through anaerobic digestion at 35, 55 and 60 °C
Legislation in Sweden and the European Union concerning the use of sewage sludge in agriculture is under revision and future concentration limits for pathogens in treated sludge are likely to be expected. The aim of this study was to evaluate the hygienization of Salmonella, Escherichia coli, Enterococcus and Clostridium perfringens through continuous anaerobic digestion at 35, 55 or 60 ...
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Improving products of anaerobic sludge digestion by microaeration
Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. ...
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Thick sludge digestion - research design and validation of key process unit operations
ABSTRACTAdvances in the design of anaerobic digesters have seen a trend towards digestion of thicker sludges in the US, UK and elsewhere. This includes a number of new facilities using bolt on technologies to mesophilic anaerobic digestion such as Cambi Thermal Hydrolysis, Prepasteurisation and Biological Hydrolysis. Cambi Thermal hydrolysis utilises thickenedsludge and the digestion process is ...
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Phosphorus release mechanisms during digestion of EBPR sludge under anaerobic, anoxic and aerobic conditions
Three laboratory-scale digesters were operated in parallel under anaerobic, anoxic and aerobic conditions to reveal the release mechanisms of phosphorus when digesting enhanced biological phosphorus removal (EBPR) sludge. The variation rates of the parameters associated with phosphorus release were calculated and compared with that of a typical EBPR anaerobic process. The results show that both ...
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Foaming during anaerobic digestion: Causes and Solutions
Foaming during sludge treatment has traditionally been associated with activated sludge systems which have been victim to this phenomenon for several decades. However, foaming has been documented in anaerobic digestion plants, leading, fundamentally, to a reduction in digester capacity and an increase in operational expenditure. The requirements for foaming of: surface active agents, gaseous ...
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Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion
Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The ...
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ARA Meiningen (AUT) Municipal Plants - Case Study
Digester: 1 x 4.000 m³ sewage sludge digestion Scope of services: sewage sludge digester agitator, flare, heat exchanger, gas equipment Start-up: ...
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Pretreatment followed by anaerobic digestion of secondary sludge for reduction of sewage sludge volume
The influence of two pretreatment methods, thermal treatment and low-pressure wet oxidation, on the sludge digestion efficiency was examined. Batch thermophilic anaerobic digestion was used to evaluate the effectiveness of the pretreatment methods in terms of volatile suspended solids (VSS) digestion efficiency and gas production. The results showed that the gas production was not proportional ...
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Grosuplje (SLO) Municipal Plants - Case Study
Digester: 2 x 635 m³ sewage sludge digestion Scope of services: sewage sludge digester agitator, flare, heat exchanger, gas storage, gas equipment Start-up: ...
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Cambi thermal hydrolysis - getting the bugs out of digestion and dewatering
Summary This paper reviews the research some of the work done over the last twenty years on the thermal pre-treatment of sludge and particularly activated sludge. It is demonstrated that the optimum time temperature for thermal pre-treatment is 170°C for half an hour. Pretreatment at 70°C has little or no effect on digestibility and dewaterability. The practical application of this approach in ...
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Dublin - Ringsend - Case Study
Client: Celtic Anglian Water Solution: CambiTHP - B12 Ringsend The WWTP at Ringsend Dublin was originally operating a two train drum drying systems for drying the raw primary sludge to meet the requirements of pasteurisation in Ireland. The plant was extended by the addition of SBR biological treatment reactors to the existing primary treatment plant. Therefore the quantity of sludge was ...
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Anaerobic digestion and thermal hydrolysis to reduce production of sludge in WWTPs
Abstract Mesophilic and thermophilic digestion of primary and activated sludge was investigated in lab scale reactors. Mixed primary and activated sludge was digested in one experiment and activated sludge was digested alone in another. The same gas yield, COD and dry solids reduction was obtained with both mesophilic and thermophilic digestion. However, more dissolved COD was found after ...
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Effect of hydraulic retention time on pretreatment of blended municipal sludge
The objective of the present work was to evaluate the effect of hydraulic retention time (HRT) on hydrolysis and acidogenesis for the pretreatment processes: acid phase digestion (APD) and autothermal thermophilic aerobic digestion (ATAD) using blended municipal sludge. The effect of the different pretreatment steps on mesophilic anaerobic digestion (MAD) was evaluated in terms of methane yield, ...
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Blending anaerobic co-digestates: synergism and economics
Co-digestion is the process in which wastes from various sources are treated together. Therefore, more organic carbon is added to make efficient use of existing digesters. The objectives of this study were to compare potential co-digestates, determine synergistic and antagonistic co-digestion outcomes and estimate economic benefits for preliminary screening. Over 80 wastes were identified from 54 ...
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Experimental power of laboratory-scale results and transferability to full-scale anaerobic digestion
Anaerobic digestion is today internationally acknowledged as an environmentally sound process for energy and nutrient recovery from organic wastes, and it is the dominant sludge treatment technology in most countries’ wastewater treatment plants. Laboratory- or pilot-scale experiments are commonly used as a first step to investigate the potential of new ideas or to confirm research hypothesis ...
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Microwave and its combined processes: an effective way for enhancing anaerobic digestion and dewaterability of sewage sludge?
The enhancement for sludge anaerobic digestion and dewaterability were investigated in sludge pretreated by microwave (MW) and its combined processes. The results showed that microwave and its combined processes can efficiently release soluble organic matter and thus enhance anaerobic digestion of sludge. The cumulative methane production in the test of the MW-H2O2-OH (0.2) process was ...
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The impact of advanced digestion on incineration of sewage sludge
Abstract Traditionally, when incineratin sewage sludge, it was preferable to burn raw undlgested sludge, as digestion - by extracting some of the energy from sludge- subsequently reduce its calorific value. However, when considering incineration as part of a wider strategy, the desicion whether or not to include digestion becomes less clear. Since, virtually all of the requirements of ...
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