Wastewater as a resource: a unique approach to achieving energy sustainability

Abstract

A wastewater-treatment flowsheet was developed to integrate uniquely designed biological processes with physical-chemical unit processes, allowing conversion of the organic carbon in the wastewater to methane, the removal and recovery of phosphorus and nitrogen from the wastewater, and the production of water suitable for reuse. In the flowsheet, energy is derived from the wastewater by first shunting a large fraction of the organic carbon in the wastewater to a solids slurry which is treated via anaerobic digestion. The anaerobic digestion system consists of focused pulsed (FP) pretreatment coupled to anaerobic membrane bioreactors (MBRs). Computer modelling and simulation results are used to optimize design of the system. Energy generation from the system is maximized and costs are reduced by using modest levels of recycle flow from the anaerobic MBRS to the FP pretreatment step.

Membrane fouling control using a rotary disk in a submerged anaerobic membrane sponge bioreactor

“…The anaerobic wastewater process is an economically attractive alternative to aerobic treatment methods because the electricity, capital, maintenance, and operating costs may be offset by methane production (Sutton et al, 2011). Anaerobic processes do not require an aeration unit, which can account for nearly one-half of the total energy input for biological wastewater treatment (Park and Craggs, 2007).…”

Treating municipal wastewater with the goal of resource recovery

“…The tubular membrane system was designed assuming an average flux of 51 l/m 2 /h. On the basis of achieving 85 percent conversion of the COD in the thickened feed solids to methane, model results indicate the optimal anaerobic digestion system (Sutton et al 2010) consists of anaerobic MBRs designed at an SRT of 43 days and a mixed-liquor TSS concentration of approximately 40 g/l. The resulting reactor HRT is 15.0 days.…”

“…In the new flowsheet depicted in Figure 1, thickened waste solids from the aerobic MBR are routed to an anaerobic digestion system operated at mesophilic temperature conditions and consisting of a solids pre-treatment step coupled to an anaerobic MBR. This reactor configuration provides numerous benefits in this application (Sutton et al 2010). The anaerobic MBR is designed around the use of tubular, ultrafiltration membranes.…”

“…The FP technology uses high voltage electrical micropulses to disrupt the biomass cell wall and membranes, releasing organic material that is more readily bioavailable for methane digestion. Information concerning design and optimization of the anaerobic digestion system is provided elsewhere (Sutton et al 2010).…”

Integrating anaerobic processes into wastewater treatment

“…In countries with moderate climates, a more holistic approach to the wastewater flowsheet has been developed (Sato et al 2006) by integrating anaerobic pretreatment of the settled wastewater prior to aerobic biological treatment. Advantages of this flowsheet include additional production of biogas from solubilised organics, a reduction in aeration energy demand facilitated by the reduction in organic load and lower biological sludge yields (Lester et al 2009;Sutton et al 2009Sutton et al , 2010. However, the low organic substrate concentration within combined sewers and low domestic wastewater temperatures have been perceived as constraints for widespread implementation of anaerobic wastewater treatment.…”