Optimization of Heterotrophic Denitrification Using Glycerol as a Sustainable External Carbon Substrate (original) (raw)
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Brazilian Journal of Chemical Engineering, 2017
This work evaluated the feasibility of glycerol as the sole carbon source for nutrient biological removal in an intermittently aerated bioreactor. The reactor operation was divided into two phases: the first one aimed only at removing nitrogen; and the second one aimed at removing nitrogen and phosphorus. In the first operational phase, three C/N (Carbon / Nitrogen) ratios were tested: 1.2, 1.5 and 1.8. For a C/N ratio of 1.8, higher denitrification efficiency was achieved (91 ± 8%). During the second phase, the reactor was subjected to periods of aeration and non-aeration of 2 h and 4 h, respectively, for a C/P (Carbon / Phosphorus) ratio of 10. The biological phosphorus removal in this phase was not significant (12 ± 9%), indicating that there was no development of PAO (Phosphorus Accumulating Organisms), since phosphate release did not occur during the anaerobic phase. This can be explained by the lack of VFA (Volatile Fatty Acids), which should come from the anaerobic degradation of the remaining amount of glycerol after denitrification was completed. The optical microscopy analysis indicated the presence of filamentous bacteria similar to the genus Beggiatoa, which could also have consumed part of the substrates from the glycerol fermentation.
Bioresource Technology, 2017
Using organic wastes as an alternative to commercial carbon sources could be beneficial by reducing costs and environmental impacts. In this study, food waste-recycling wastewater (FRW) was evaluated as an alternative carbon source for biological denitrification over a period of seven months in a full-scale sewage wastewater treatment plant. The denitrification performance was stable with a mean nitrate removal efficiency of 97.2%. Propionate was initially the most persistent volatile fatty acid, but was completely utilized after 19 days. Eubacteriacea, Saprospiraceae, Rhodocyclaceae and Comamonadaceae were the major bacterial families during FRW treatment and were regarded as responsible for hydrolysis (former two) and nitrate removal (latter two) of FRW. These results demonstrate that FRW can be an effective external carbon source; process stabilization was linked to the acclimation and function of bacterial populations to the change of carbon source.
Wastewater from Biodiesel Production as a Carbon Source for Denitrification of Sludge Liquor in SBR
Chemical and Biochemical Engineering Quarterly, 2010
Sludge liquor from an anaerobic sludge digester with an average N–NH 4 concentration of 1185 mg L –1 was treated in a pilot-scale SBR (sequencing batch reactor) system. The returned activated sludge of a WWTP was used as inoculum. The average efficiency of N–NH 4 removal was over 90 %. Concentrations of N–NH 4 in the effluent were typically below 10 mg L –1 . The maximal achieved nitrification rate was r N 9.1 mg g –1 h –1 (relative to MLVSS). Wastewater of methyl ester wash arising during biodiesel production was used as an external carbon source for denitrification. A dosage of 3.5 – 4.5 g of COD per 1 g of nitrogen available for denitrification was found optimal. Typical effluent N–NO 3 concentration was about 25 mg L –1 and maximal achieved denitrification rate was r D 14.5 mg g –1 h –1 . Operation of the SBR was stable at a HRT of 4 – 5 days.
Environmental Research, 2020
A three-dimensional biofilm-electrode reactor (3D-BER) was constructed to facilitate the tertiary denitrification of the secondary effluent of wastewater treatment plants (SEWTP) under 12 mA and in the absence of a carbon source. The TN removal efficiency was 63.8%. The path of the formation and transformation of nitrogen, the relationship between the TN and COD removal rate and the relative concentration and composition of organic matter in the influent and effluent were analyzed to clarify the possible pathways of N and C transformation in the 3D-BER system. Under the action of an electric current, 4.4 mg NH 4 þ-N⋅L À 1 and 17.7 mg COD⋅L À 1 accumulated in the 3D-BER system, and the removal rates of TN and COD were strongly and positively correlated (R 2 ¼ 0.9353). The microorganisms in the 3D-BER system under the action of electric current secreted organic matter, some of which (humic acid and microbial metabolites) could be further electrolyzed by microorganisms into bioavailable organic matter for heterotrophic denitrification. Partially dissolved organic matter (DOM, tryptophan aromatic protein, humic acid and microbial metabolites) in the SEWTP could be hydrolyzed under the action of the electric current in the 3D-BER system and consisted of bioavailable organic matter for heterotrophic denitrification. The contribution of heterotrophic denitrification to TN removal was greater than 11.7%. Therefore, the 3D-BER system removed a portion of DOM through microbial electrohydrolysis and promoted the coupling of hydrogen autotrophic denitrification and heterotrophic denitrification to enhance the effectiveness of nitrogen removal in SEWTP. Overall, this technique is effective for enhancing tertiary denitrification in SEWTP.
Water Science & Technology
Glycerol is commonly employed for denitrification purposes in full-scale wastewater treatment. In non-acclimatized biomass, the glycerol is very inefficient resulting in a high C/N ratio and low-standard denitrification rates. The acclimatization is driven by the microbial enrichment of Saccharimonadales and Propionibacteriales as found in different sampled municipal sludges flanking the dominant presence of Burkholderiales. The selective strategy is based on a very efficient process in terms of C/N ratios and standard denitrification rates, but it leads to nitrite accumulation. As a result, severe and unexpected nitrous oxide emissions were found in full-scale with emission factors up to 2.5% kgN2O (kgKJNremoved)−1. Simultaneous dosage of isobutirate in a full-scale experiment could counter the nitrous oxide emissions. As nitrous oxide emissions were found proportional to the dosed glycerol-based COD, the authors suggest that, in case of acclimatization of biomass to glycerol, an e...
Combined biodegradation of carbon, nitrogen and phosphorus from wastewaters
Journal of Molecular Catalysis B: Enzymatic, 1998
The objective of this study was to develop an integrated system for simultaneous removal of carbon, nitrogen and phosphorus from industrial wastewaters. The system consisted a two step anaerobic digestion reactor for carbon removal Ž . coupled with a sequencing batch reactor SBR for nutrient removal. In the proposed system, carbon is converted into biogaz Ž . by methanogenic activities. The volatile fatty acids VFA produced during the first step of anaerobic digestion were used as electron donors for biological dephosphatation in the SBR in which anaerobic and aerobic phases were cyclically applied. It was shown that nitrification of ammonia took place in the SBR reactor, during the aerobic phase. Furthermore, denitrification and VFA production were achieved together in the acidogenic reactor, when the efflux of nitrate from the SBR is added to the acidogenic influx. The proposed process was fed with a synthetic wastewater with composition Ž . y1 Ž . y1 characteristics: Total Organic Carbon TOC s 2200 mg l ; Total Kjedahl Nitrogen TKN s 86 mg l ; Phosphorus under Ž .
Chemical Engineering & Process Techniques Co-Digestion of Glycerol with Municipal Wastewater
The production of biodiesel, an environmentally friendly alternative to fossil based fuel sources, is creating a surplus of crude glycerol (CG). As CG is a highly regulated waste stream, new and effective methodologies to process CG into useful products are needed to cover the costs associated with its disposal. In this paper we present the results of a study that used a demonstration-scale low-energy high-rate anaerobic aerobic digestion (HRAAD) system to evaluate the potential of co-digesting CG with sewage wastewater (primary clarifier effluent, PCE). The HRAAD system consisted of an initial anaerobic packed bed (AnPB) reactorfed a PCE-glycerol mixture possessing a chemical oxygen demand (COD) of 3.07 g l-1 at a hydraulic residence time (HRT) of 2 days (organic loading rate (OLR) of 1.53 kg m-3 d-1) and achieved a COD reduction of approximately 65%. The biogas produced possessed 65% methane (CH 4) at a yield of 0.20 m 3 CH 4 per kg COD red at standard temperature and pressure (STP).The effluent from the AnPB (COD: 1.083 g l-1 , OLR: 1.28 kg COD m-3 d-1) was fed to the second downstream aerobic trickling filter (TF) reactor that produced an effluent COD of 0.809 g l-1 achieving an overall HRAAD system COD reduction of 74% (i.e. across both AnPB and TF reactors). Ammonia reduction across the AnPB reactor was 68% with a total system reduction of 91%. Nitrites and nitrates in both reactor effluents were completely absent. In total, these results support that the co-digestion of high strength acidic CG (COD: ~1.5 kg l-1 and pH: 4) with sewage wastewater is an attractive solution to process excess CG.
Biodiesel waste as source of organic carbon for municipal WWTP denitrification
Bioresource Technology, 2009
This paper presents the results of experiments to test biodiesel waste (glycerine -g-phase) as an organic carbon source for the removal of nitrate in a WWTP denitrification process. Investigation of g-phase was first centered on g-phase utilization as an external source for denitrification under laboratory conditions and consequently, after positive results from the laboratory investigation, g-phase was applied in the denitrification process in the WWTP Vrútky (35,000 PE). This WWTP had insufficient nitrogen removal via denitrification. Denitrification was insufficient due to an influent with a low BOD 5 /N ratio (1.7:1) entering into the activated sludge tank. Laboratory experiments and calculations showed that, to reach N total concentration under 10 mg l À1 in effluent, a biodiesel waste dose of 500 kg COD d À1 was necessary. Glycerol phase (g-phase) dosing into the denitrification tank increased denitrification efficiency by 2:0 À 5:0 mg NO 3 -N l À1 per 100 l of g-phase dose into the denitrification tank.