digested primary sludge Articles

  • Aerators Enhance Aerobic Digestion Process

    The city of Eden,N.C.,operates an extended aeration process designed for an average flow rate of 13.5 mgd with a mixed liquor suspended solids concentration that typically checks in about 6,000 mg/l. This high biomass concentration is necessary to provide a well-settling sludge and good effluent quality. Further, the plant influent is approximately 40% domestic wastewater and 60% industrial ...


    By S&N Airoflo Inc.

  • Energy self-sufficient sewage wastewater treatment plants: is optimized anaerobic sludge digestion the key?

    The anaerobic digestion of primary and waste activated sludge generates biogas that can be converted into energy to power the operation of a sewage wastewater treatment plant (WWTP). But can the biogas generated by anaerobic sludge digestion ever completely satisfy the electricity requirements of a WWTP with ‘standard’ energy consumption (i.e. industrial pollution not treated, no ...


    By IWA Publishing

  • The Effect of the Microsludgetm Treatment Process on Anaerobic Digestion Performance

    ABSTRACT Thickened waste activated sludge (TWAS) from biological treatment processes is less amenable to anaerobic digestion than primary sludge. This is due to TWAS being composed mostly of cellular material and extracellular polymeric substances (EPS) instead of more easily digestible carbohydrates and fats that are typically found in primary sludge. In an attempt to improve TWAS digestion ...

  • Increased biogas production in a wastewater treatment plant by anaerobic co-digestion of fruit and vegetable waste and sewer sludge – A full scale study

    Anaerobic digestion is a well established technology for the reduction of organic matter and stabilization of wastewater. Biogas, a mixture of methane and carbon dioxide, is produced as a useful by-product of the process. Current solid waste management at the city of Prince George is focused on disposal of waste and not on energy recovery. Co-digestion of fresh fruit and vegetable waste with ...


    By IWA Publishing

  • 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 ...


    By United Utilities

  • Improved Anaerobic Digestion Feed Systems and Concepts

    The sludge feed systems for anaerobic digestion facilities at wastewater plants in North America have been and continue to be modified and upgraded for a variety of reasons. These reasons include operational problems and issues, evolution from prior primary-sludge-only digestion facilities, performance-based reasons, regulatory-based reasons, and include the desire to improve the digestion ...

  • Synergistic application of advanced primary and secondary wastewater treatment systems

    Published in Water and Waste Digest membrane issue, November 2008 Miroslav Colic; Chief Scientist, Clean Water Technology Inc., Los Angeles, CA To be published in Water and Waste Digest later this year The increased regulatory pressures and demand for reused water stimulated development of several new wastewater technologies in the last decade. Advanced treatment systems are ...

  • 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 ...


    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 ...

  • Pollutants in Urban Wastewater and Sewage Sludge

    Untitled Document Executive Summary Water policy in the European Union is aiming to promote sustainable water use and a major ...

  • Toluene in sewage and sludge in wastewater treatment plants

    Toluene is a compound that often occurs in municipal wastewater ranging from detectable levels up to 237 μg/L. Before the year 2000, the presence of the aromatic hydrocarbons was assigned only to external sources. The Enhanced Biological Nutrients Removal Processes (EBNRP) work according to many different schemes and technologies. For high-efficiency biological denitrification and ...


    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 ...

  • Semi-continuous mesophilic anaerobic co-digestion of thermally pretreated scum

    The objective of this study is to investigate the mesophilic, anaerobic, co-digestion of scum with thickened waste activated sludge (TWAS) and primary sludge (PS). Observations of the reactor waste show that higher pretreatment temperatures assist in scum integration and appear to limit coagulation and separation effects associated with digesting fats, oils and greases. The 0.40 kg VS/m3 · d ...


    By IWA Publishing

  • The effect of iron and aluminium for phosphorus removal on anaerobic digestion and organic sulfur generation

    The addition of iron or aluminium into activated sludge basins for phosphorus removal is likely to impact both the efficiency of the anaerobic digestion process and the generation of odor-causing compounds following digestion and dewatering. In this study, the impact of iron and aluminium addition on digestion and odor-causing compounds was investigated by using batch digestion of combined ...


    By IWA Publishing

  • Design and Operational Considerations to Avoid Excessive Anaerobic Digester Foaming

    Excessive foaming in anaerobic digesters has been a problem for many years. All anaerobic digesters will foam to some extent, but excessive foam can be problematic. Excessive foaming is defined as foam that interferes with flow through the gas piping system and/or is not contained within the digester. Causes of foaming include presence of excessive filamentous bacteria, extreme amounts of oils ...

  • Thermal hydrolysis pre-treatment for high solids anaerobic digestion

    The City and County of San Francisco completed a two-year pilot study of pre-treatment processes to mesophilic anaerobic digestion for improved biosolids stabilization and production of biosolids suitable for unrestricted reuse (class A biosolids). The results of this effort will help in the design of the new Solids Handling Facility (SHF) at the 11 m3/s Southeast Water Pollution Control Plant ...


    By Cambi Group AS

  • Relative kinetics of anaerobic digestion under thermophilic and mesophilic conditions

    With several advantages over the conventional mesophilic anaerobic digestion, such as better sludge quality and higher biogas production, thermophilic anaerobic digestion is regarded as a promising alternative for sludge digestion. Primary and activated sludges are complex materials, and historically, analysis of kinetics has been largely on whole sludge, without analysis of individual ...


    By IWA Publishing

  • 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 ...


    By Cambi Group AS

  • Village of Maybrook, NY Sludge Dewatering System

    Project Summary: The Village of Maybrook WWTP process consists of primary clarification, trickling filters, and secondary clarification. Primary sludge and trickling filter humus is anaerobically digested. The belt filter press dewaters the sludge eliminating the need for sludge drying beds. The belt filter press discharge cake solids are consistently in the 25 to 30 percent range, which is ...


    By BDP Industries

  • Municipal WWTP Digester Cleanout - Jekyll Island, Georgia - Case Study

    Coastal Georgia's Jekyll Island Stale Park, a popular vacation destination, is also home to about 750 permanent residents. John Day, Superintendent of the Water and Wastewater plants, operates the Jekyll Island Authority's I MGD wastewater treatment plant. Structural modifications and improvements to the plant's two anaerobic digesters were scheduled for early 2004. The job was publicly bid and ...

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