alkaline digester Articles

  • Alkaline treatment of high-solids sludge and its application to anaerobic digestion

    High-solids anaerobic digestion is a promising new process for sludge reduction and bioenergy recovery, requiring smaller digestion tanks and less energy for heating, but a longer digestion time, than traditional low-solids anaerobic digestion. To accelerate this process, alkaline sludge disintegration was tested as a pretreatment method for anaerobic digestion of high-solids sludge. The results ...


    By IWA Publishing

  • Evaluation of alkalinity spatial distribution in an up-flow fixed bed anaerobic digester

    In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up-flow fixed bed reactor for the treatment of tequila vinasses is presented. Measurements of volatile fatty acids, pH, alkalinity and bicarbonate were obtained at three sampling points in the reactor in the axial axis. Then, the spatial distribution of alkalinity is studied and discussed. Moreover, ...


    By IWA Publishing

  • Effect of thermal alkaline pretreatment on the anaerobic digestion of wasted activated sludge

    The effect of alkaline pretreatment of waste-activated sludge, using two models to study the sequential hydrolysis rates of suspended (Sanders' surface model) and dissolved (Goel's saturation model) solids, on the mesophilic and thermophilic anaerobic digestion rate is evaluated. The pretreatment, which reduces the size of the solids, increases the reaction rate by increasing the surface area and ...


    By IWA Publishing

  • Enhancement of waste activated sludge anaerobic digestion by a novel chemical free acid/alkaline pretreatment using electrolysis

    Anaerobic digestion of waste activated sludge (WAS) is relatively poor due to hydrolysis limitations. Acid and alkaline pretreatments are effective in enhancing hydrolysis leading to higher methane yields. However, chemical costs often prohibit full-scale application. In this study, 12 V two-chamber electrolysis using an anion exchange membrane alters sludge pH without chemical dosing. pH ...


    By IWA Publishing

  • Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at ...


    By IWA Publishing

  • Enzymatic kinetic parameters for polyfluorinated alkyl phosphate hydrolysis by alkaline phosphatase

    The hydrolysis kinetics of three polyfluorinated alkyl phosphate monoesters (monoPAPs), differing in fluorinated chain length, were measured using bovine intestinal alkaline phosphatase to catalyze the reaction. Kinetic values were also measured for analogous hydrogenated phosphate monoesters to elucidate the effects of the fluorinated chain on the rate of enzymatic hydrolysis. Michaelis ...


    By John Wiley & Sons, Ltd.

  • High dry solids digestion

    ABSTRACTDigestion of sewage sludge normally takes place at pH values between 7,0 and 7,5. Control methods of the process stability are based on practical experience such as the ratio of volatile fatty acids (VFA) and total alkalinity (TA). Thermal sludge disintegration for an enhanced digestion process allows a digester feed with higher dry solids concentrations. This is due to an opening of ...


    By Cambi Group AS

  • High dry solids digestion

    Abstract Digestion of sewage sludge normally takes place at pH values between 7,0 and 7,5. Control methods of the process stability are based on practical experience such as the ratio of volatile fatty acids (VFA) and total alkalinity (TA). Thermal sludge disintegration for an enhanced digestion process allows a digester feed with higher dry solids concentrations. This is due to an ...


    By Cambi Group AS

  • Improved methane production from waste activated sludge with low organic content by alkaline pretreatment at pH 10

    Sludge with low organic content always results in an unsatisfactory performance, even failure of anaerobic digestion. The alkaline pretreatment effect on anaerobic digestion of sludge with low organic content has seldom been studied although it gives many benefits for sludge with high organic content. In this study the influence of alkaline pretreatment (pH 10, an effective alkaline pH) on the ...


    By IWA Publishing

  • Biosolids Minimization using Integrated Alkaline Sludge Hydrolysis and Biological Nutrient Removal Process

     ABSTRACT This paper presents a pilot-scale evaluation of an integrated approach to sludge management utilizing a combination of biological nutrient removal and biosolids alkaline hydrolysis, as well as attempts to explore the impact of recycled alkaline hydrolysates on sludge yield and anaerobic digestion. The novel concept of converting an existing conventional activated sludge (CAS) ...

  • Prediction of Strutive Formation Potential in EBPR Digested Sludges

    ABSTRACTLow operating costs and less sludge generation associated with EBPR (Enhanced Biological Phosphorus Removal) have led existing wastewater treatment plants to retrofit their phosphorus removal systems and have encouraged new plants to incorporate EBPR into their design. However, in plants that use anaerobic digestion, the introduction of EBPR may result in the formation of scales of the ...

  • Maize mono-digestion efficiency: results from laboratory tests

    A laboratory experimental campaign was carried out in order to assess the optimal configuration for the anaerobic digestion of a mixture of sweet corn and ensiled maize. Batch hydrolysis tests were conducted at 35 and 55 °C and at four different particle sizes (2, 5, 20 and 50 mm) obtained by manual chopping and sieving. Chemical pre-treatment by 24 h incubation at various acid and alkaline pH ...


    By IWA Publishing

  • 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

  • Comparison of sidestream treatment technologies: post aerobic digestion and Anammox

    Post aerobic digestion (PAD) and anaerobic ammonium oxidation (Anammox) are sidestream treatment technologies which are both excellent options for the reduction of nitrogen recycled back to the liquid stream without the need for supplemental carbon or alkalinity. However, the achievement of this goal is where the similarities between the two technologies end. PAD is an advanced digestion ...


    By IWA Publishing

  • 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

  • Development and Application of Biological H2S Scrubbers for Treatment of Digester Gas

    ABSTRACTAs part of the California Energy Group (Former California Energy Commission) Public Interest Energy Research (PIER) Program, biological hydrogen sulfide (H2S) biogas cleaning was evaluated. The biological H2S scrubber uses bacteria to oxidize the sulfide to produce both elementary sulfur and sulfuric acid. This system was tested at the Inland Empire Utilities Agency’s Regional Plant 1 ...

  • A review: factors affecting excess sludge anaerobic digestion for volatile fatty acids production

    This paper presents a review of methods that improve the production of volatile fatty acids (VFA) from excess sludge during the anaerobic digestion process. These methods are mainly divided into two approaches. The first approach is located in the pre-treatment methods, which change the properties of the substrates, such as thermal pre-treatment, alkaline pre-treatment, microwave pre-treatment ...


    By IWA Publishing

  • Struvite precipitation in raw and co-digested swine slurries for nutrients recovery in batch reactors

    The release of nitrogen (N) and phosphorus (P) from agro-industrial sources is a major environmental concern. Furthermore, the scarcity of mineable P and the growing demand for food worldwide necessitate that we find an alternative P source. This study applied struvite precipitation for N-P recovery to slurries with high levels of organics and ammonia to achieve environmental protection from ...


    By IWA Publishing

  • Modified ADM1 for high-rate anaerobic co-digestion of thermally pre-treated brewery surplus yeast wastewater

    Co-digestion of surplus yeast with brewery wastewater is a potentially economical method for recovering energy, in the form of biogas, from this difficult to dispose of by-product. In this work a modified version of the ADM1 (Anaerobic Digestion Model No. 1) was calibrated for an anaerobic digester fed with thermally pre-treated brewery yeast surplus wastewater. The model could predict changes ...


    By IWA Publishing

  • The use of microalgae and their culture medium for biogas production in an integrated cycle

    Vinasse is a residue produced in large quantities as a sub-product of ethanol production. Anaerobic digestion of vinasse can yield large amounts of biogas, but often difficulties arise in maintaining stable operation, due to the acidity of the material (which has a pH between 3.5 and 5) and a strong tendency to further acidification. Anaerobically digested vinasse can be used as part of a ...


    By IWA Publishing

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