anaerobic digester mixing Articles

  • The effect of mixing conditions on anaerobic digester performance

    The basic principle of aerobic wastewater treatment is the conversion of some parts of organic matters to biomass and this causes production of excessive sludge in aerobic processes. This excessive sludge is withdrawn from time to time to prevent accumulation of biomass in aeration basin. In most cases, this sludge requires the stabilization before the dewatering and disposal. Different processes ...


    By ORBIT e.V.

  • Anaerobic Digester Mixing Modifications Ease Rising Natural Gas Prices

    By modifying the process used to thicken incoming raw and waste activated sludge to the City of Massillon’s anaerobic digesters and through the establishment of proper mixing and heating of the digester contents, the City has benefited by reducing their natural gas consumption for which the average cost of natural gas has increased 275 percent from 2003 to 2006. These modifications have resulted ...

  • Restoration of Active Anaerobic Digestion in Charleston, West Virginia

    The upgrade to the Charleston, West Virginia wastewater treatment plant is a 50-million dollar project that is being conducted in two phases. The first phase of the project included specific unit processes at the plant that were failing or causing significant operational impairments. This first phase included the emergency renovation of four (4) existing anaerobic digesters that at the onset of ...

  • Advantages of anaerobic digestion of sludge in microaerobic conditions

    The paper reviews results and experience of microaerobic experiments at both high and low sulphide concentrations and evaluates advantages and drawbacks of the anaerobic digestion of sludge in microaerobic conditions as regards biogas quality, digested sludge quality, organic pollutants biodegradability and methanogenic activity of biomass. The innovative microaerobic modification of the ...


    By IWA Publishing

  • Installation of Radar Level Instruments in Anaerobic Digesters

    ABSTRACTThere are numerous well-proven options available for level determination instrumentation. Instrumenting treatment processes present some unique challenges. Some of these include the ability for wastewater or residuals to clog and blind instruments. Level determination in an anaerobic digester presents these problems as well as others including foaming, surface agitation, and operation in ...

  • Combined experiences of thermal hydrolysis and anaerobic digestion

    The basic principles of batch thermal hydrolysis process (THP) are well known and have been put into full practice in 20 plants around the world. This paper reviews the historical development of the process and the latest thinking on the application of THP from a number of sources in Europe. An independent investigation of the vendors claims support the data for the benefits claimed to date. The ...


    By Cambi AS

  • Residential SSO To High Solids Anaerobic Digestion

    Source separated organics, including kitchen and garden waste, are processed in a dry AD plant. Resulting biomethane is injected into an adjacent natural gas pipeline. Winterthur, a city in the canton of Zürich in northern Switzerland, has the country’s sixth largest population, estimated at more than 100,000. In 2011, the City of Winterthur launched a 2050 energy policy to ...


    By BioCycle Magazine

  • Anaerobic digestion of mixed microalgae cultivated in secondary effluent under mesophilic and thermophilic conditions

    The anaerobic digestion of mixed indigenous microalgae, grown in a secondary effluent, was evaluated in batch tests at mesophilic (35°C) and thermophilic (50°C) conditions. Under mesophilic conditions, specific methane production varied from 178 to 207 mL CH4/g volatile solids (VS) and the maximum production rate varied from 8.8 to 26.1 mL CH4/(gVS day), depending on the type of ...


    By IWA Publishing

  • H2 consumption by anaerobic non-methanogenic mixed cultures

    The impact of H2 consumption, by homoacetogens, on the overall hydrogen yield in mixed culture fermentation is the focus of this study. Batch reactors were used to test the ability of anaerobic digested sludge, heat treated to eliminate methanogens, to produce and consume molecular hydrogen. The measured average hydrogen production rate from 4.2 g glucose/L was 44 ± 4 mmol H2/L sludge · d, while ...


    By IWA Publishing

  • Digester Developers Target Mixed Organic Waste Streams

     emerging group of commercial companies see a viable business opportunity in North America around building, owning and operating larger scale anaerobic digestion (AD) facilities to process mixed organic waste streams. In some instances, the projects being proposed and constructed only include anaerobic digester operations. In others, there is a combination of digestion with back-end ...


    By BioCycle Magazine

  • Velocity gradient as a tool to characterise the link between mixing and biogas production in anaerobic waste digesters

    Whilst the importance of mixing in anaerobic digesters to enhance process performance and gas production is well recognised, the specific effects of mixing regime on biogas production are not clear. Here, the velocity gradient is used to demonstrate the importance of minimally mixed zones in a digester, with computational fluid dynamics (CFD) models indicating that 20–85% of a ...


    By IWA Publishing

  • 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 ...

  • Applying Rheological Techniques to Upgrade Anaerobic Digesters and Handle High Solids Concentrations

    The Orange County Sanitation District (OCSD) is implementing a Capital Improvements Program that includes upgrading their wastewater treatment Plant No. 1 in Fountain Valley, California to full secondary treatment. The expansion will increase both primary and secondary solids production. OCSD prepared a Long-Range Biosolids Management Plan that concluded the waste solids should continue to be ...

  • 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 ...


    By Cambi AS

  • Fate of phosphate during anaerobic digestion of sludge from an EBPR plant

    Phosphate at Whitlingham STW Phosphorus Consent Requirement To comply with a total phosphate limit of 1.54 mg/l on an 80%ile basis: this is equivalent to an annual average of 1.0 mg/l (UWWTR for PE’s > 100,000) assuming the usual lognormal distribution or 80% removal To achieve this standard in a sustainable way, and without using metal salts ...


    By Cambi AS

  • Climate change impacts of food waste diversion to anaerobic digesters

    Treating food waste (FW) by anaerobic digestion to recover biogas and biofertiliser is a fantastic opportunity. The biogas is renewable, base-load, non-fossil energy. Using the digestate on land as biofertiliser completes nutrient cycles and conserves soil organic matter. The Part-503 rules protect health and the environment. Existing sludge digesters can be ‘turbo-charged’ by retrofitting ...


  • Anaerobic digestion foaming in full-scale biogas plants: a survey on causes and solutions

    Anaerobic digestion foaming is a common operation problem in biogas plants with negative impacts on the biogas plants economy and environment. A survey of 16 Danish full-scale biogas plants on foaming problems revealed that most of them had experienced foaming in their processes up to three times per year. Foaming incidents often lasted from one day to three weeks, causing 20–50% ...


    By IWA Publishing

  • Two-phase anaerobic digestion for class a biosolids at moccasin bend WWTP

    The Moccasin Bend Wastewater Treatment Plant (WWTP) provides treatment for the City of Chattanooga, Tennessee and the surrounding region. The City has completed upgrades to the solids handling facilities to treat and dewater the primary solids and waste activated sludge (WAS) from the WWTP. This paper summarizes the process to handle the primary solids and the start-up process. Primary solids ...

  • Two-phase anaerobic co-digestion of food waste and sewage sludge

    The feasibility and performance of food waste and sewage sludge co-digestion were investigated to gain insight into their resource utilization. In this study, two-phase anaerobic digestion (TPAD) was operated under a total solids mixing ratio of 1:1 and different sludge retention times (SRTs). Results show that an acidogenic reactor with a 5-day SRT obtained the highest acidification efficiency, ...


    By IWA Publishing

  • Making Cogeneration Pencil Out: Anaerobic Co-Digestion of Grease Trap Waste

    At the end of 2006 the City of Millbrae, California completed a $5.5 million wastewater treatment plant improvement project at no additional cost to the City’s ratepayers. The project improved cogeneration facilities, provided an automated grease trap waste receiving station, improved digester heating, replaced the aging main electrical switchgear, and enhanced digester mixing. Costs for the ...

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