Full-scale application of focused-pulsed pre-treatment for improving biosolids digestion and conversion to methane

Abstract

We tested at full-scale the innovative Focused Pulsed (FP) technology for pre-treating waste sludge in order to improve methane gas production and biosolids reduction in sludge digestion, but without incurring problems of odors, toxicity, and high costs for chemical or energy consumption. FP pre-treatment of a mixture of primary and secondary sludge increased the soluble COD by 160% and DOC 120% over the control. FP pre-treatment of 63% of the input waste sludge increased biogas production by over 40% and reduced biosolids requiring disposal by 30% when compared to the plant baseline. FP pre-treatment also correlated with a shift of the bacterial and archaeal communities. The most significant change was that the acetate-cleaving Methanosaeta became the dominant methanogen. Full FP pre-treatment should increase biogas production and biosolids removal by 60% and 40%, respectively. Full FP pre-treatment should generate energy benefits of at least 2.7 times and as high as 18 times the FP energy input, depending on heat recovery from FP treatment. For a plant treating 76,000 m3/d of wastewater (380 m3-sludge/d), FP treatment should generate an annual economic benefit of approximately $540,000 net of electricity and other operating and maintenance costs. This represents a payback period of three years or less.

Syntrophic interactions among anode respiring bacteria (ARB) and Non‐ARB in a biofilm anode: electron balances

“…The anaerobic digested sludge used as the inoculum was characterized in an earlier work (Rittmann et al, 2008a) and consisted of acetoclastic and hydrogenotrophic methanogens, along with other anaerobic bacteria. We added 0.49 mL of ethanol to 320 mL of anode volume to give an electron mass of 100 meq (26 mM), placed an Ag/AgCl reference electrode in the anode compartment (BASI Electrochemistry, West Lafayette, IN, MF-2052) less than 1 cm apart from the working electrode to control the anode potential using a potentiostat (Princeton Applied Research, Model VMP3, Oak Ridge, TN), and poised the potential at À200 mV versus Ag/AgCl, which ensured that the ARB were not limited by anode potential .…”

Using pyrosequencing and quantitative PCR to analyze microbial communities

“…In the second example, it was investigated how the microbial ecology in a full-scale anaerobic digester was altered when the digester's methane production rate was significantly increased by Focused Pulsed (FP) pretreatment, which make complex biologic solids more bioavailable by exposing them to rapid pulses of a very strong electric field [20,21]. Using QPCR, a shift in methanogens to the acetate-cleaving Methanosaeta and away from the H 2 -oxidizing Methanoculleus is first observed.…”

Integrating High-Throughput Pyrosequencing and Quantitative Real-Time PCR to Analyze Complex Microbial Communities

“…In the second example, we investigated how the microbial ecology in full-scale anaerobic digester was altered when the digester's methane production rate was significantly increased by Focused Pulsed (FP) (OpenCEL ® ) Technology pre-treatment, which make complex biological solids more bioavailable by exposing them to rapid pulses of a very strong electric field (19,20). Using QPCR, we first observed a shift in methanogens to the acetate-cleaving Methanosaeta and away from the H 2 -oxidizing Methanoculleus.…”