Feasibility of Focused‐Pulsed Treated Waste Activated Sludge as a Supplemental Electron Donor for Denitrification

Abstract

We evaluated the feasibility of using waste activated sludge (WAS) from a wastewater treatment plant as an internal electron donor to fuel denitrification, by increasing its bioavailability with Focused-Pulsed (FP) technology. The focused-pulsed treatment of WAS (producing FP-WAS) increased the semi-soluble chemical oxygen demand (SSCOD) by 26 times compared with the control WAS. The maximum denitrification rate of FP-WAS (0.25 g nitrate-nitrogen [NO 3 2 -N]/g volatile suspended solids [VSS]?d) was greater than for untreated WAS (0.05 g NO 3 2 -N/g VSS?d) and methanol (0.15 NO 3 2 -N/g VSS?d).Centrifuging out the larger suspended solids created FP-centrate, which had a rate (0.14 g NO 3 2 -N/g VSS?d) comparable with that of methanol. Thus, FP treatment of WAS created SSCOD, which was an internal electron donor that was able to drive denitrification at a rate similar to or greater than methanol. One trade-off of using FP-WAS for denitrification is an increase in total Kjeldahl nitrogen (TKN) loading. While FP-WAS achieved the lowest total nitrogen and NO 3 2 -N concentrations in the batch denitrification test, its final ammonia-nitrogen (NH 3 -N) concentration was the highest, as a result of the release of organic nitrogen from the FPtreated biomass; FP-centrate had less release of total soluble nitrogen. While the return of total nitrogen (TN) is small compared with the SSCOD, the effects of the added nitrogen loading need to be considered. Water Environ. Res., 82, 2316Res., 82, (2010.

Application of Internal Carbon Source from Sewage Sludge: A Vital Measure to Improve Nitrogen Removal Efficiency of Low C/N Wastewater

“…Numerous sludge treatment technologies to increase VFAs have been developed, mainly including physical processes (such as mechanical treatment, focused-pulsed, and ultrasound) [59][60][61], fermentation processes (alkaline and acid fermentation) [61][62][63][64][65], and their combination [66,67]. These techniques are used to break sludge floc into a small fraction of soluble COD (SCOD, such as VFAs) [59], or translate long and non-degradable organic substances into short and biodegradable COD [68].…”

“…The result showed that denitrification rates improved after the addition of disintegrated sludge (36.7 mg NO 3 -N g −1 /VSS h −1 ) compared with the control (30.2 mg NO 3 -N g −1 /VSS h −1 ) and were even higher than acetate as an additional source (34.7 mg NO 3 -N g −1 /VSS h −1 ). Lee et al [61] evaluated the feasibility of focused-pulsed, and the result showed that VFAs increased 5.1-fold relative to untreated WAS. The batch-test denitrification rate of focused-pulsed-WAS (0.25 gNO 3 -N/g VSS d) was higher than that of untreated WAS (0.05 g NO 3 -N/g VSS d) and methanol (0.15 gNO 3 -N/g VSS d).…”

Application of Pulsed Electric Energy for Lignocellulosic Biorefinery

“…Microbiological analysis of sludge revealed significant increases of organics in the presence of several methanogenic microbiological species. Bench-scale of FP pretreatment applied to secondary sludge had showed rapid denitrification kinetics because of the electron donor having high SCOD and ammonia concentrations (Lee et al 2010). At a treatment intensity of 16 kWh/m 3 the semisoluble chemical oxygen demand (COD) had increased by 16 times.…”

An Experimental 13.56 MHZ Radio Frequency Heating System for Efficient Thermal Pretreatment of Wastewater Sludge

“…The pre-treatment process breaks down floc to increase the availability of intracellular organic material that is solubilized in the liquid. Different pre-treatment methods can be used including chemical [4], biological [5][6][7], mechanical [8,9], thermal [4,8,[10][11][12][13] and non-thermal pulse powered processes [14][15][16]. Of these methods, thermal pre-treatment processes have been shown to be highly effective, and the design of efficient heating methods to pre-treatment wastewater sludge has motivated this research work.…”