To investigate the distribution and dynamics of microbial community in anaerobic digestion at agitated and non-agitated condition, 454 pyrosequencing of 16s rRNA was conducted. It revealed the distinct community compositions between the two digesters and their progressive shifting over time. Methanogens and syntrophic bacteria were found much less abundant in the agitated digester, which was ma...

the start up dynamics of a one-million and two-hundred-thousand liter anaerobic digester of municipal waste treatment sludge was studied. in the digester, mixing was accomplished by circulation of the produced biogas at a rate of 0.13 m3 per hour of the digester volume per hour. during the nine-month study, no serious phenomena of foaming, getting sour, temperature fall, etc. were observed desp...

In this study, a wrapper approach was applied to objectively select the most important variables related to two different anaerobic digestion imbalances, acidogenic states and foaming. This feature selection method, implemented in artificial neural networks (ANN), was performed using input and output data from a fully instrumented pilot plant (1 m3 upflow fixed bed digester). Results for acidog...

Sewage sludge management is an energy intensive process. Anaerobic digestion contributes to energy efficiency improvement but is limited by the biological process. A review has been conducted prior to experimentation in order to evaluate the mass and energy balances on anaerobic digestion followed by gasification of digested sludge. The purpose was to improve energy recovery and reuse. Calculat...

Computational Fluid Dynamics (CFD) was used to simulate the mixing characteristics of four different circular anaerobic digester tanks (diameters of 13.7, 21.3, 30.5, and 33.5m) equipped with single and multiple draft impeller tube mixers. Rates of mixing of step and slug injection of tracers were calculated from which digester volume turnover time (DVTT), mixture diffusion time (MDT), and hydr...

Credit: Cornerstone Environmental Group Anaerobic digesters are a mature, proven technology. They take sludge, manure, and other organic waste materials and produce methane (natural gas) fuel. Nobody questions their technological capabilities. However, the question remains as to their economic benefits. In terms of dollars and cents, how much economic sense do anaerobic digesters make? What are...

The aim of this study was to examine sludge granulation during the anaerobic treatment of pre-hydrolysed municipal wastewater. The pretreated wastewater had a total chemical oxygen demand (CODt) of 432 ± 20 mg/l, a soluble COD (CODs) of 259 ± 8 mg/l, volatile fatty acids (VFA) of 101 ± 9 mg/l and suspended solids (SS) of 94 ± 12 mg/l. Prior to entering the digester, the influent was supplemente...

Wastewater is increasingly viewed as a resource, with anaerobic digester technology being routinely implemented for biogas production. Characterising the microbial communities involved in wastewater treatment facilities and their anaerobic digesters is considered key to their optimal design and operation. Amplicon sequencing of the 16S rRNA gene allows high-throughput monitoring of these system...

An anaerobic digester receiving food waste collected mainly from domestic kitchens was monitored over a period of 426 days. During this time information was gathered on the waste input material, the biogas production, and the digestate characteristics. A mass balance accounted for over 90% of the material entering the plant leaving as gaseous or digestate products. A comprehensive energy balanc...