Treatment Of High-strength Wastewater Research Articles

Performance evaluation and organic mass balance for treatment of high strength wastewater by anaerobic hybrid membrane bioreactor

AbstractThe performance and chemical oxygen demand (COD) mass balance of a lab‐scale anaerobic hybrid membrane bioreactor (An‐HMBR), treating high strength wastewater, at mesophilic temperature, was investigated. Long‐term (275 days) operation was carried out at various hydraulic retention times (HRTs), namely, 3, 2, 1, and 0.5 days corresponding to organic loading rate (OLR) of 1.06, 1.6, 3.2, and 6.4 kg COD/m3d, respectively. An‐HMBR achieved, COD removal of 97–87% at HRT of 3–0.5 days, respectively. The study showed that polyurethane foam as attached growth media adsorbed mixed liquor suspended solids and thereby reduced the load on the membrane by 42%. During COD mass balance, an additional 4–5% of COD balance was achieved by consideration of COD conversion to biomass. The results suggest that unknown COD fraction varies between 33 and 37%, which was attributed to the loss of gaseous as well as oversaturation of dissolved methane. Consideration of oversaturation leads to a COD mass balance of over 95%.

Treatment of high-strength olive mill wastewater by combined Fenton-like oxidation and coagulation/flocculation

The efficiency of Fenton/Fenton-like processes on the oxidation of organic matter from real olive mill wastewater (OMW) is described. Tests were performed in lab-scale batch reactors and the influence of different operational parameters was evaluated, namely: type of iron salt, effect of pH readjustments during the reaction, reactants addition method and Fe/H2O2 mass ratio. For the Fenton-like system (Fe3+/H2O2) it was found that H2O2 consumption and consequently total organic carbon (TOC) degradation rate are significantly affected by the reagents addition method, especially in earlier stages of the reaction, although the overall extent of TOC removal is not. Results showed that the gradual addition of H2O2 along with pH readjustments during the process led to better chemical oxygen demand (COD) and total phenolic content (TPh) reduction. Operating at pH0 = 3.0, T0 = 25 °C, [Fe3+] = 1.0 g·L−1 and Fe/H2O2 = 0.04, 34.9% of TOC, 55.7% of COD and 81.4% of TPh were removed after 180 min. The same conditions were applied with the assistance of artificial radiation (photo-Fenton-like process) with slight organic matter degradation improvement (41.8% of TOC, 63.2% of COD and 83.8% of TPh removals). The catalyst’s (ferric chloride salt) ability to act as a coagulant/flocculant after the oxidative process was also checked, being reached a global reduction of 76.7% for COD and 96.4% for TPh after 1 h of sedimentation and no further pH adjustments. Moreover, the effluent’s biodegradability (BOD5:COD ratio) after the combined process improved from the initial value of 0.11 to 0.33, and toxicity against the bioluminescent Vibrio fischeri bacteria decreased from 53% to 4%, putting into evidence the possibility of coupling downstream a biological unit so that the final effluent meets legal discharge limits.

Treatment of real sodium saccharin wastewater using multistage contact oxidation reactor and microbial community analysis

In this study, multistage contact oxidation reactor (MCOR) with a novel carrier was used for treatment of high-strength sodium saccharin wastewater (SSW) under stepwise increasing salinities from 1.0% to 8.0%. The results revealed that MCOR could effectively remove the organic pollutants from SSW when influent salinity was no more than 4.5%; the chemical oxygen demand (COD) and NH4+-N removal efficiency under the optimal operating parameters ranged up to 91.5% and 92.7%, respectively. Microbial diversity analysis illustrated that the dominant microbes in SSW treatment system were substantially distinct at different salinities. Pseudomonas was predominant at salinity of 3.5%, while Marinobacterium (a species involved in COD removal) was enriched to a greater degree at salinity of 7.0%. CCA suggested that salinity was the main factor for dynamic evolutions of microbial community structures. This work demonstrated that MCOR is an appropriate method for the treatment of high-strength, high-salinity SSW.

Robustness of anammox granular sludge treating low-strength sewage under various shock loadings: Microbial mechanism and little N2O emission

With the increasing application of anammox for the treatment of high-strength industrial wastewater, application of anammox in municipal sewage has been gaining more attention. Sludge granulation in particular enhances the enrichment and retention of anammox bacteria in municipal sewage treatment systems. However, the performance of granular sludge under continuous and varying hydraulic loading shock remains little understood. In this study, the robustness of anammox granular sludge in treating low-strength municipal sewage under various shock loadings was investigated. Results showed that an upflow anaerobic sludge blanket (UASB) reactor with anammox granules performed well, with anammox specific activity up to 0.28 kg N/kg VSS/day and anti-loading shock capability up to 187.2 L/day during the 8-month testing period. The accumulation rate of N2O (<0.01 kg N/kg VSS/day) in the liquid phase was seven times higher than that of the gas phase, which could be mainly attributed to the incomplete denitrification and insufficient carbon source. However, only a small part of the produced N2O escaped into the atmosphere. High-throughput sequencing and molecular ecological network analyses also identified the bacterial diversity and community structure, indicating the potential resistance against loading shock. The composition and structural analyses showed that polysaccharides were an important functional component in the tightly bound extracellular polymeric substances (TB-EPS), which was the major EPS layer of anammox granules. Scanning electron microscopy (SEM) also showed that the gaps in between the anammox-clusters in the granules inhibit the flotation of the sludge and ensure efficient settling and retention of anammox granules.

Treatment of high strength industrial wastewater with membrane bioreactors for water reuse: Effect of pre-treatment with aerobic granular sludge on system performance and fouling tendency

In this study, the treatment of citrus wastewater with membrane bioreactors (MBRs) under different configurations was investigated for water reuse. In particular, one MBR and one aerobic granular sludge MBR (AGS + MBR) bench scale plants were operated for 60 days. The experimental campaign was divided into two periods. In Phase I, a conventional hollow fiber MBR was employed for the treatment of the raw high strength wastewater, whereas in Phase II a combination of in-series reactors (AGS + MBR) was adopted for the treatment of the high strength citrus wastewaterThe results demonstrated that both plant configurations enabled very high COD removal, with average values close to 99%. Respirometric batch tests revealed a considerable high metabolic activity of the biomass in both plant configurations, with higher values in the AGS + MBR. It was speculated that the MBR reactor was enriched in active biomass deriving from the erosion of the external granule layers in the upstream reactor. In terms of fouling tendency, higher resistance to filtration was observed in the AGS + MBR plant, also characterized by higher irremovable resistance increase compared to the MBR plant, that might severely affect the membrane service life.

Electricity production and treatment of high-strength dairy wastewater in a microbial fuel cell using acclimated electrogenic consortium

Microbial fuel cells are innovative technologies that can efficiently remove chemical oxygen demand and biochemical oxygen demand, while simultaneously generating electricity, with a minimal environmental footprint. High efficiencies have recently been achieved for the treatment of low-strength wastewater. However, in treatment of a real high-strength wastewater, such as dairy effluent, the efficiency decreases drastically due to operational instability associated with environmental fluctuations, difficulty of maintaining the run for long periods, and fouling. In order to overcome these issues, a new initialization method was developed, with a start-up phase employing an inoculum composed of a consortium of fermenting and metal-reducing bacteria, followed by acclimation and treatment phases. The protocol employed enabled removal of 90% of total biochemical oxygen demand, 62% of total chemical oxygen demand, 72% of total Kjeldahl nitrogen, 71% of sodium, and 65% of ultraviolet absorbing substances from dairy wastewater. Furthermore, the microbial fuel cell produced maximum power densities of 1.45 W/m3 in the acclimation phase and 1.32 W/m3 in the treatment phase. The findings demonstrated that microbial fuel cells powered by real high-strength dairy wastewater can achieve high efficiencies.

Nitrogen Removal by Heterotrophic Nitrifying Bacterium Pseudomonas putida YH and Its Kinetic Characteristics

Due to the low nitrogen removal efficiency, lengthy procedure, and vulnerability to high loads of ammonium of the traditional sewage treatment process, the physiological characteristics, nitrogen removal characteristics, influencing factors, and kinetic analysis were systematically studied for the heterotrophic nitrifier Pseudomonas putida YH, which has efficient nitrogen removal ability. The results showed that strain YH exhibited efficient heterotrophic nitrification ability with a low accumulation of nitrification products. The maximum ammonium removal rate was 99.1%, and nearly 53% of the removed TN was converted to intracellular nitrogen. In addition, nitrite and nitrate could also be metabolized by strain YH under aerobic conditions, with a maximum removal rate of 99.8% and 99.5%, respectively. Additionally, the successful PCR amplification of the napA and nirK genes further improved the aerobic denitrification characteristics of strain YH. The bacterial growth process of strain YH matched the Logistic model (R2>0.99), and the nitrogen degradation conformed to the Compertz model (R2>0.99). The order of the maximum conversion rates of nitrogen (Rm) was ammonia > nitrate > nitrite, and that of the lag time (t0) was nitrate > nitrite > ammonia. The optimal conditions for heterotrophic ammonium oxidation with strain YH were succinate as the carbon source, C/N=10, T=30℃, r=160-200 r·min-1, and pH=7.0. Under the optimal conditions, the average ammonia oxidation rate and Rm were 8.35 and 16.71 mg·(L·h)-1, respectively. Strain YH could adapt to a broad range of ammonium loads. A high ammonium removal rate was observed under high ammonium concentrations (1000 mg·L-1), indicating the high potential of strain YH for application in high-strength ammonium wastewater treatment.

Developing a multi-criteria decision support system based on fuzzy analytical hierarchical process (AHP) method for selection of appropriate high-strength wastewater treatment plant

The selection of an optimum treatment process for high-strength wastewater is complicated. Familiarity with wastewater treatment methods is not enough to design a plant and requires a multidisciplinary knowledge base. In this research, five alternative wastewater treatment methods for high-strength wastewater were investigated and ranked based on the analytic hierarchy process (AHP) fuzzy method: upflow anaerobic sludge blanket (UASB) + membrane bioreactor (MBR), UASB + extended aeration (EA), anaerobic baffled reactor (ABR), anaerobic lagoon (ANL) + aerated lagoon (AL), and sequencing batch reactor (SBR) + ABR. These treatment methods were ranked based on five criteria, namely energy consumption, effluent total suspended solids (TSS), effluent chemical oxygen demand (COD), cost, and level of technology. The different options of the wastewater treatment plant were rated by expert decision-makers in this field. The results show that for typical high-strength wastewater, the use of an UASB reactor followed by a MBR is the most appropriate alternative for treating the wastewater.

Sources of anammox granular sludge and their sustainability in treating low-strength wastewater

Anaerobic ammonium oxidation (anammox) has been widely applied in the treatment of high-strength nitrogen wastewaters. However, few engineering practices were reported to treat low-strength nitrogen wastewaters. In this study, three types of anammox granular sludge (GS) were separately collected from the expanded granular sludge bed (EGSB) reactors treating nitrogen wastewaters at high (H-), moderate (M-) and low (L-) nitrogen loading rates (NLRs), and employed for the treatment of low-strength nitrogen wastewater in sequencing batch advanced nitrogen removal (ANR) systems. The ANR system with M-GS (namely M-ANR system) was most useful. At the initial biomass concentration of 2.43 g-VSS·L−1, cycle length of 8 h and influent total nitrogen (TN) concentration of less than 15 mg·L−1, the performance data were as follows: effluent TN of less than 1 mg·L−1, TN removal efficiency of more than 92.8%, the nitrogen removal rate (NRR) of 0.039 kg-N·m−3·d−1. The efficient performance lasted as long as 46 cycles, indicating the sustainability of the M-ANR system. The advanced microscopic analysis and metagenomic analysis were applied to reveal the successful but non-permanent treatment by the M-ANR system. The long-time lag between biomass decay and sludge activity decay provided a window period for the good performance of M-ANR system. However, the weak support of oligotrophic habitat for anaerobic ammonium oxidizing bacteria community was doomed to the degradation of anammox GS, resulting in gradual loss of their activities. A periodic addition of fresh M-GS or a periodic rejuvenation cultivation in the eutrophic habitat is necessary to achieve a permanent performance.

Energy efficient COD and N-removal from high-strength wastewater by a passively aerated GAO dominated biofilm

Conventional aerobic treatment of high-strength wastewater is not economical due to excessively high energy requirement for compressed air supply. The use of passive aeration avoids the use of compressed air and enables energy efficient oxygen supply directly from the air. This study evaluates a passively aerated simultaneous nitrification and denitrification performing biofilm to treat concentrated wastewater. The biofilm reactor was operated > 5-months under alternating anaerobic/aerobic conditions. For 4-times concentrated wastewater, > 80% COD (2307 mg L−1 h−1) and > 60% N (60 mg L−1 h−1) was removed at a hydraulic retention time (HRT) of 7 h. A double application in the same reactor enabled > 95% COD and 85% N-removal, at an overall HRT of 14 h which is substantially shorter than what traditional activated sludge-based systems would require for the treatment of such concentrated feeds. Microbial community analysis showed Candidatus competibacter (27%) and nitrifying bacteria (Nitrosomonas, and Nitrospira) as key microbes involved in COD and N-removal, respectively.

AnMBR Treatment of High-Strength Starch-Based Wastewater: Impact of Cleaning Process and CEBs on Membrane Fouling

AbstractAn anaerobic continuously stirred tank reactor (CSTR) integrated with an external tubular nanofiltration membrane module was operated for 466 days. Studies were conducted to compare the eff...

A modified upflow anaerobic sludge blanket reactor as an alternative for decentralized domestic wastewater treatment in developing countries

AbstractThe aim of this paper was to evaluate the performance of two modified upflow anaerobic reactor (RAns) as a decentralized technology for the treatment of high-strength domestic wastewater. Two full-scale anaerobic reactors (Ran1 and Ran2) with the same configuration and total volume of 14.6 m³, total height of 2.57 m, and constructed from fibreglass reinforced plastics were operated with a 16-hour hydraulic retention time and submitted to a volumetric organic load less than 2.7 kg chemical oxygen demand (COD)·m−3·d−1. The RAns were monitored for 10 consecutive months and showed the capability to support the fluctuations of organic loading and volumetric rates. The compact anaerobic reactors proved to be effective in removing organic matter (biological oxygen demand removal efficiencies greater than 70% and the average soluble COD removal efficiencies greater than 57.4%). The solids profile in the reactor ranged from very dense particles with good settleability close to the bottom (sludge bed) to a more dispersed and light sludge close to the top of the reactor (sludge blanket), similar to conventional UASB reactors.

Nitrogen removal from iron oxide red wastewater via partial nitritation-Anammox based on two-stage zeolite biological aerated filter

Partial nitritation-anaerobic ammonium oxidation (PN-Anammox) was successfully applied for high-strength ammonium iron oxide red wastewater (IORW) treatment based on stable PN performance of zeolite-biological aerated filter (ZBAF). By separating Na2CO3 dosage avoid the high free ammonia (FA) inhibited nitritation, two-stage ZBAF was applied for achieving efficient PN with Na2CO3 as the alkalinity donor and saving about 40.0% of the alkalinity cost compared to NaHCO3. Moreover, Anammox was used for further nitrogen removal from IORW and stable total nitrogen (TN) removal was obtained at the influent NH4+-N concentration of 567 mg/L and TN removal efficiency kept above 70.0% after 100 days operation. High throughput sequencing-based approaches showed that Nitrosomoadaceae (AOB) and Kuenenia was dominance in two-stage ZBAF and Anammox samples respectively, while Nitrospire and Nitrobacter (NOB) undetected. The combined process should have advantages for similar high-strength ammonium wastewater treatment.

Conversion of organic compounds into biogas on a full scale brewery WWTP using IC reactor

Wastewater from breweries usually contains high levels of organic components, which are generally easily biodegradable. Ideally, the mainstream method of brewery wastewater treatment is based on biological transformation, which have been reported to be effective in efficiently reducing COD concentration. Anaerobic digestion technology plays an important role in the treatment of high strength wastewater [1]. The benefit of the process is biogas production and recovering the energy. The main goal of the paper is to present the results of a full-scale research performed in a brewery WWTP in 2016. Wastewater from brewery containing COD, a priority pollutant of organic components, is treated in IC reactor. The biogas produced during the anaerobic digestion is transformed into heat. Total COD and soluble COD were measured 5 days a week in wastewater before and after anaerobic reactor. In raw wastewater, average total COD was 5226 mg/L with the percentage share of soluble COD 89.4%. As a result of anaerobic treatment 83,7% reduction of total COD and 92.9% reduction of soluble COD were obtained. The average daily biogas production was 4089 m3/d.

Coupling Granular Activated Carbon Adsorption with Membrane Filtration for Chemical Oxygen Demand Removal from High Strength Wastewater

Combined granular activated carbon adsorption with membrane filtration for high strength wastewater treatment have been carried out. Raw oleo-chemical wastewater and leachate were used as sample. Ultrafiltration is also relatively low cost, easy to backwash and operates up to 3 barg. Experiment was carried out by passing through the sample to an adsorption column for 10 minutes followed by membrane filtration at different transmembrane pressure of 1, 2 and 3 barg. Oleo-chemical samples were analysed for chemical oxygen demand, turbidity, suspended solid and leachate samples were analysed for chemical oxygen demand and ammonia nitrogen according to APHA method. Results showed that the best chemical oxygen demand, suspended solids and turbidity removal for oleo-chemical samples achieved at 2 bar with 64%, 93% and 97%, respectively. Leachate showed the best removal of chemical oxygen demand and ammonia nitrogen achieved at 3 bar, with 76% and 87%, respectively. The adsorption process combined with membrane filtration is feasible as an alternative for conventional biological treatment for high strength wastewater. However, GAC exhaustive breakthrough point requires monitoring.

Treatment of high-strength sulfate wastewater with EGSB reactor

Treatment of high-strength sulfate wastewater with EGSB reactor

Performance of Two-Stage A/O Process on High-Strength Ammonia Nitrogen Wastewater

In order to understand the two-stage A/O process which contained two independent A/O (Anoxic/Oxic) subsystems when applied to treat high-strength ammonia nitrogen wastewater, connection mode of the two A/O subsystems and DO concentration of oxic phase were selected as the influencing factors in this paper. The connection modes of the two independent A/O subsystems were parallel-connected and tandem-connected. Initially, the performance of two-stage A/O process in different connection modes were investigated by comparing the ability to remove COD, NH4+-N and TN. It was observed that tandem-connected two-stage A/O system was suitable for the treatment of high-strength ammonia nitrogen wastewater, and two-stage A/O system which was operated in parallel-connected mode failed to meet the direct emission standard of Discharge Standard of Water Pollutants for Ammonia Industry in China (GB13458-2013) with remanent COD, NH4+-N and final effluent TN concentration of 234.2mg/L, 25mg/L and 74.2mg/L, respectively. Following the above observation, five different levels of DO concentration (2, 3, 4, 5 and 6 mg/L) of stage-one and stage-two were varied to figure out the optimal DO concentration in tandem-connected two-stage A/O system. Examination of effluent quality indicated that 5.0mg/L was determined to be the optimal DO concentration for Stage-one and 2.0mg/L for Stage-two. In this case, the quality of effluent was perfectly satisfied the direct emission standard.

Synergy of N-(3-oxohexanoyl)-L-homoserine lactone and tryptophan-like outer extracellular substances in granular sludge dominated by aerobic ammonia-oxidizing bacteria.

Nitrogen removal via nitrite is an energy-saving method for high-strength ammonia wastewater treatment. A better understanding of the formation of granular sludge dominated by aerobic ammonia-oxidizing bacteria (AerAOB) could facilitate the improved use of rapid sludge granulation for nitritation. In this study, AerAOB-dominated activated sludge (NAS) and granular sludge (NGS) produced different N-scyl-homoserine lactones (AHLs). N-(3-oxohexanoyl)-L-homoserinelactone (OHHL), only released from NGS, was shown to accelerate sludge aggregation by increasing the biomass growth rate, microbial activity, extracellular protein, and AerAOB biomass. For both NAS and NGS, sludge cells were glued together by inner extracellular polymeric substances (EPSs) with similar components to form microcolony. Different from the characterized negative effect of NAS's outer-EPS on cell adhesion, the outer-EPS of NGS played a positive role in the attached growth of AerAOB-dominated sludge and contained more tryptophan-like substances. More interesting, OHHL enhanced the yields of tryptophan-like substances after mixing with the outer-EPS of NGS, enhancing cell adhesion. In a word, OHHL and more tryptophan-like substances were produced in the process of granulation under the selective sludge discharge condition, which was proved to be able to accelerate NAS granulation. Therefore, the sludge granulation process for nitritation can be improved by increasing the levels of OHHL and tryptophan in the initial startup stage. The appropriate engineering strategy should be further studied to facilitate the actual application of granular sludge for nitrogen removal on a large scale.

Optimization of organics to nutrients (COD:N:P) ratio for aerobic granular sludge treating high-strength organic wastewater

The present study attempted to optimize the nutrients required for biological growth and biomass synthesis in the treatment of high-strength organics wastewater using aerobic granular sludge (AGS). Three identical sequencing batch reactors (SBRs) were used to cultivate aerobic granules at COD concentration of ~5000 mg/L at COD:N:P ratios of 100:2.8:0.4, 100:4.4:0.5, and 100:5:0.7. Results indicated that the amount of nutrients needed for biomass growth does not follow the conventional organics to nutrients ratio (COD:N:P) of 100:5:1 when dealing with high-strength organics wastewater. The highest removal efficiency was achieved at COD:N:P ratio of 100:2.8:0.4, where COD, TN, and P removal was 98.8 ± 0.3%, 100.0 ± 0.0%, and 99.3 ± 1.0%, respectively. Moreover, the presence of high amounts of organics led to the dominance of the fast-growing heterotrophs in all SBRs, with the genus Thauera identified as the most abundant genera (23-40%), while autotrophic nitrifiers disappeared. The observed biomass yield at COD:N ratio of 100:2.8 suggested that heterotrophic nitrification may have occurred, while at COD:N ratios of 100:4.4 and 100:5, all the nitrogen was used for biomass synthesis. Moreover, at COD:N ratio of 100:5, almost 1/5 of the organics were utilized by the biomass cells to produce EPS as defensive action against the effects of free ammonia. Batch optimization experiments showed that the fastest rate of removal occurred at COD:N:P ratio of 100:1.1:0.4. After 4 h, the COD, TN, and P removal efficiencies were 95%, 99%, and 96%, achieving overall removal efficiencies of 98%, 100%, and 97% respectively, at HRT of 8 h. The bacterial behavior in consuming the organics was altered under nutrient-deficient conditions, where faster degradation rates were observed as the amounts of nutrients decreased, with higher relative abundance of heterotrophs and diazotrophic bacterial populations.

Greenhouse gas emission reduction and carbon credit revenue in a waste leachate treatment plant

As the largest emitter, China faces great challenges of controlling greenhouse gas (GHG) emissions, including those from wastewater treatment plant. In recent years, however, emission trading is becoming an attractive approach to help the plant owners implement cleaner treatment technologies to reduce their GHG emissions. Among these, the advanced anaerobic process such as up-flow anaerobic sludge semi-fixed filter (UASSF) is competent in high strength wastewater treatment, and renders much more carbon credits than other conventional anaerobic systems. This paper presents a study on emission reduction based on the UASSF system in a waste leachate treatment plant (WLTP). The calculation results show that the total GHG emission reductions can achieve 16217.9 metric tons of carbon dioxide equivalents (tCO2e) per year. Owing to the emission trading and energy recovery, the running cost of the project is reduced from 4.12 to 1.69 € per ton leachate. Also, the good social and ecological benefits can be achieved due to the significant reductions of anthropogenic emission.