Mustard Tuber Wastewater Research Articles

Impact of salinity and organic matter on the ammonia-oxidizing archaea and bacteria in treating hypersaline industrial wastewater: amoA gene abundance and ammonia removal contributions.

Studies publishedrecently proposed that ammonia-oxidizing archaea (AOA) may bebeneficial for hypersaline (salinity > 50g NaCl L-1) industrial wastewater treatment. However, knowledge of AOA activity in hypersaline bioreactors is limited. This study investigated the effects of salinity, organic matter, and practical pickled mustard tuber wastewater (PMTW) on AOA and ammonia-oxidizing bacteria (AOB) in two sequencing batch biofilm reactors (SBBRs). Results showed that despite observed salinity inhibition (p < 0.05), both AOA and AOB contributed to high ammonia removal efficiency at a salinity of 70 g NaCl L-1 in the two SBBRs. The ammonia removal efficiency of SBBR2 did not significantly differ from that of SBBR1 in the absence of organic matter (p > 0.05). Batch tests and quantitative real-time PCR (qPCR) reveal that salinity and organic matter inhibition resulted in a sharp decline in specific ammonia oxidation rates and amoA gene copy numbers of AOA and AOB (p < 0.05). AOA demonstrated higher abundance and more active ammonia oxidation activity in hypersaline and high organic matter environments. Salinity was positively correlated with the potential ammonia oxidation contribution of AOA (p < 0.05), resulting in a potential transition from AOB dominance to AOA dominance in SBBR1 as salinity levels rose. Moreover, autochthonous AOA in PMTW promoted the abundance and ammonia oxidation activities of AOA in SBBR2, further elevating the nitrification removal efficiency after feeding the practical PMTW. AOA demonstrates greater tolerance tothe challenging hypersaline environment, making it a valuable candidate for the treatment of practical industrial wastewater with high salinity and organic content.

Performance of simultaneous carbon and nitrogen removal of high-salinity wastewater in heterotrophic nitrification-aerobic denitrification mode

In this work, heterotrophic nitrification-aerobic denitrification (HN-AD) mode was successfully established after a 105-day acclimation in a sequencing batch reactor (SBR) system using mustard tuber wastewater (MTWW) as substrate. The performance of simultaneous carbon and nitrogen removal (SCNR) was investigated using manual wastewater within the salinity from 1% to 6%. Results indicate that high salinity caused little effect on carbon removal, while it brought a significant influence on nitrogen removal. At the salinity of 1% and 3%, the heterotrophic nitrification rates were 2.83 and 3.96-fold of those of the autotrophic nitrification, respectively. As the salinity was up to 6%, the autotrophic nitrification was significantly inhibited, while the anoxic denitrification was slightly affected and the aerobic denitrification became dominant. The analysis on microbial community structure of the acclimated wastewater sludge reveals that the genera with autotrophic nitrification were gradually eliminated with an increasing salinity during the acclimation. Paracoccus, Pseudomonas, Alcaligenes and Bacillus were the dominant genera related to HN-AD process. The optimal operation parameters for SCNR were investigated, including C/N ratio (25), DO concentration (6 mg/L) and temperature (35 °C). This work provides an insight into the migration of nitrogen removal pathway and the succession of HN-AD microbial community in the process of high-salt wastewater biotreatment.

Performance and Bacterial Characteristics of Aerobic Granular Sludge in Treatment of Ultra-Hypersaline Mustard Tuber Wastewater

Mustard tuber wastewater (MTW) is an ultra-hypersaline high-strength acid organic wastewater. Aerobic granular sludge (AGS) has been demonstrated to have high tolerance to high organic loading rate (OLR), high salinity, and broad pH ranges. However, most studies were conducted under single stress, and the performance of AGS under multiple stresses (high salinity, high OLR, and low pH) was still unclear. Herein, mature AGS was used to try to treat the real MTW at 9% salinity, pH of 4.1–6.7, and OLR of 1.8–7.2 kg COD/m3·d. The OLR was increased, and the results showed that the upper OLR boundary of AGS was 5.4 kg COD/m3·d (pH of 4.2) with relatively compact structure and high removal of TOC (~93.1%), NH4+-N (~88.2%), and TP (~50.6%). Under 7.2 kg COD/m3·d (pH of 4.1), most of the AGS was fragmented, primarily due to the multiple stresses. 16S rRNA sequencing indicated that Halomonas dominated the reactor during the whole process with the presence of unclassified-f-Flavobacteriaceae, Aequorivita, Paracoccus, Bradymonas, and Cryomorpha, which played key roles in the removal of TOC, nitrogen, and phosphorus. This study investigated the performance of AGS under multiple stresses, and also brought a new route for highly-efficient simultaneous nitrification–denitrifying phosphorus removal of real MTW.

Hypersaline Wastewater Produced from Pickled Mustard Tuber (Chinese Zhacai): Current Treatment Status and Prospects

Pickled mustard tuber, a worldwide condiment, is increasing at a fast growth rate. Its production generates a considerable amount of hypersaline wastewater containing NaCl of 7 wt.%, COD of 30,000 mg L−1, NH3-N of 400 mg L−1, and TP of 300 mg L−1. Pickled mustard tuber wastewater (PMTW) has severe effects on crops, deterioration of water quality, soil infertility and ecological systems. Due to the technic difficulties and insufficient support from the local governments; however, PMTW has not yet been widely investigated and well summarized. Therefore, this manuscript reviewed the relatively latest advances in PMTW. Physicochemical and biological hybrid processes mainly treat PMTW and the corresponding cost is 6.00 US dollars per ton. In the context of double carbon capture capacity in China and the development of the pickled mustard industry, PMTW sauce and sustainable reuse such as nutrient recovery, acid and alkaline regeneration and renewable energy may be bright prospects.

Assessment of High Salinity Wastewater Treatment with Dewatered Alum Sludge-Aerobic Membrane Reactor

Abstract The discharge of wastewater containing both high salinity and high organic content without prior treatment is detrimental to aquatic life and water hygiene. In order to integrate the advantages of membrane treatment and biological treatment, and exert the phosphorus removal efficiency of dewatered alum sludge, in this study, an aerobic membrane reactor based on dehydrated alum sludge was used to treat mustard tuber wastewater with salinity of 6.8-7.3 % under the conditions of 30 °C, 20 kPa trans-membrane pressure (TMP) and chemical oxygen demand (COD) of 3300-3900 mg/L. Three replicate reactors were applied to assess the operational performance under different organic loading rate (OLR). The results showed that all reactors were effective in removing COD, ammonia nitrogen (NH4 +-N) and soluble phosphate (SP) under the conditions of 30 °C and 20 kPa of TMP. Meanwhile, the effluent concentration of COD, NH4 +-N and SP all increased while OLR was changed from 1.0 to 3.0 kg COD/m3/day, and the effluent COD and NH4 +-N concentration except for SP could reach the B-level of Chinese “Wastewater quality standards for discharge to municipal sewers” when OLR was less than 3.0 kg COD/m3/day. This indicates that dewatered alum sludge-based aerobic membrane reactor is a promising bio-measure for treating high salinity wastewater.

Green environment and sustainable development: methods and applications

Abstract The discharge of wastewater containing both high salinity and high organic content without prior treatment is detrimental to aquatic life and water hygiene. In order to integrate the advantages of membrane treatment and biological treatment, and exert the phosphorus removal efficiency of dewatered alum sludge, in this study, an aerobic membrane reactor based on dehydrated alum sludge was used to treat mustard tuber wastewater with salinity of 6.8-7.3 % under the conditions of 30 °C, 20 kPa trans-membrane pressure (TMP) and chemical oxygen demand (COD) of 3300-3900 mg/L. Three replicate reactors were applied to assess the operational performance under different organic loading rate (OLR). The results showed that all reactors were effective in removing COD, ammonia nitrogen (NH4 +-N) and soluble phosphate (SP) under the conditions of 30 °C and 20 kPa of TMP. Meanwhile, the effluent concentration of COD, NH4 +-N and SP all increased while OLR was changed from 1.0 to 3.0 kg COD/m3/day, and the effluent COD and NH4 +-N concentration except for SP could reach the B-level of Chinese “Wastewater quality standards for discharge to municipal sewers” when OLR was less than 3.0 kg COD/m3/day. This indicates that dewatered alum sludge-based aerobic membrane reactor is a promising bio-measure for treating high salinity wastewater.

Packed cage rotating biological contactor for mustard tuber wastewater treatment: Performance and microbiome along the axial direction

Due to the alternate exposure of the biofilm to wastewater and air, the rotating biological contactors (RBCs) provide a changing biofilm external environment for microbiome growth. In this study, a novel packed cage rotating biological contactor (PCRBC) system, with more artificially intensified biofilm and higher oxygen mass transfer efficiency, was applied to treating mustard tuber wastewater (MTWW). The capacity and kinetics of pollutants removal was evaluated based on Monod Equation and Illumina MiSeq techniques were used to detect the spatial distribution of microorganism community along the flow pathway. The results illustrated that the PCRBC has a good performance on COD, NH4+-N and TN with removal efficiencies over 90.49%, 99.12% and 70.82%, respectively. The bacterium community populations at the middle and distal end of the PCRBC train were completely different from those at the beginning of the PCRBC. However, the strong ecological associations were observed among different bacteria. Except for conventional denitrification pathway, the heterotrophic nitrification-aerobic denitrifying (HN-AD) combined with short-cut denitrification was inferred as the main denitrification pathways, especially at the middle and end of the PCRBC. This study presents a novel perspective to interpret the resilience of the PCRBC through the deeper analysis of the bacterium community dynamics which was supposed to help guiding optimization strategies for more effective pollutant removal.

Treatment of mustard tuber wastewater (MTWW) using a pilot-scale packed cage rotating biological contactor system: process modeling and optimization.

The water quality range for wastewater treatment projects in the food processing industry changes constantly. To fully understand the threshold for pollutant removal with the lowest possible energy consumption, the relationship between pollutant removal and wastewater treatment conditions was established using response surface methodology (RSM). The optimum conditions for total COD, TN, and NH3-N removal from saline mustard tuber wastewater (MTWW) with a packed cage rotating biological contactor (RBC) system were investigated by experiments based on a Box-Behnken design (BBD). The independent variables were organic load (ORL), rotational disk velocity (RDV), and immersion rate (IR). Parameters of COD, TN, and NH3-N removal efficiency were selected as responses. The optimal conditions for the best COD, TN, and NH3-N removal efficiency with the lowest energy consumption were found to be at an ORL of 26.71 kg/day, a RDV of 1.62 rpm (7.62 m/s), and an IR of 46%. After the optimization, the energy cost was evaluated by coupling energy performance indicators with organic pollution efficiencies to be the highest class of performance. This research demonstrates that the suggested models have a good predicting and fitting ability in interrelations between the pollutant removal and process parameters of the packed cage RBC system treating saline MTWW.

Simultaneous electricity generation and nitrogen and carbon removal in single-chamber microbial fuel cell for high-salinity wastewater treatment

Simultaneous power generation and nitrogen and carbon removal were achieved in a single-chamber microbial fuel cell for high-salinity mustard tuber wastewater treatment. The results showed that mustard tuber wastewater, which was a self-buffered electrolyte, could be used as a suitable fuel for providing a maximum power density of 8.3 ± 0.2 W/m3 at a C/N ratio of 7. Furthermore, the removal efficiencies of chemical oxygen demand, ammonia, and total nitrogen were 86.09%, 96.55%, and 96.17%, respectively, at a C/N ratio of 4. Batch experiments showed that simultaneous nitrification and denitrification occurred in the single-chamber microbial fuel cell. A microbial community analysis revealed that heterotrophic nitrifiers (including Thauera, Paracoccus, Arcobacter, and Flavobacterium), heterotrophic denitrifiers (including Thauera, Vitellibacter, Caldithrix, Candidatus_Competibacter, Castellaniella, and Rheinheimera), and sulfur autotrophic denitrifiers (including Sedimenticola, Stappia, Sulfurovum, and Thioalbus) were enriched for nitrogen removal. Moreover, sulfate reduction considerably promoted carbon removal but lowered the nitrogen removal efficiency. These findings will aid in developing methods for mustard tuber wastewater efficient treatment.

Long-term stable and energy-neutral mixed biofilm electrode for complete nitrogen removal from high-salinity wastewater: Mechanism and microbial community

The steady mixed biofilm electrode (MBE) was investigated for the removal of nitrogen from mustard tuber wastewater. Results showed that complete nitrogen removal occurred over a wide initial chemical oxygen demand (COD)/total nitrogen (TN) ratio ranging from 2.8 to 9.8 using MBE. MBE revealed broad-spectrum applicability for the treatment of high-salinity wastewater containing different forms of nitrogen. Bio-electrochemical process, in-situ heterotrophic nitrogen reduction, ammonia stripping, nitrogen assimilation, and endogenous denitrification coexisted for the removal of nitrogen. Batch activity tests and functional microorganism analysis confirmed that autotrophic/heterotrophic nitrification, anoxic/aerobic denitrification, and nitrogen bio-electrochemical reduction cooperated to achieve efficient nitrogen conversion. More importantly, the analysis of the preliminary energy balance demonstrated that MBE was self-sustaining. The long-term operation stability of MBE was of great importance for its practical application. The results provided herein offer new insights into bioelectrochemical nitrogen removal and resource treatment of high-salinity wastewater.

Efficient nitrogen removal in a modified sequencing batch biofilm reactor treating hypersaline mustard tuber wastewater: The potential multiple pathways and key microorganisms

This study first compared the efficiencies and mechanisms of the nitrogen removal in an aerobic sequencing batch biofilm reactor (SBBR) treating mustard tuber wastewater from high salt (30 gNaCl L−1) to ultra-high salt (70 gNaCl L−1). High-efficiency maintaining of nitrification was observed. Despite of high BOD5/TN (5.5–9), distinct denitrification decline for lack of carbon in response to salt stress was observed. Considering the high concentrations of sulfate in mustard wastewater, and the existence of sulfur-reducing bacteria (SRB) and sulfur-driven denitrifiers (DNSOB) in the aerobic SBBR, sulfate reduction-sulfur autotrophic denitrification process is a feasible idea to solve this problem. By modified to intermittent aeration mode, sulfur cycle was developed in SBBR. The average removal efficiency of COD, TN reached 85.20% and 98.56%, respectively. By batch activity tests and microbial community analysis, ammonia oxidation activity by ammonia-oxidizing archaea (AOA) was observed, and high abundance of AOA (Arch-amoA/AOB amoA: 2.38 × 102) together with ammonia-oxidizing bacteria (AOB) of Nitrosomonas_halophila (1.23%) ensured the high efficient nitrification. After running mode change, specific sulfur-driven NO3−-N reduction rate increased and the abundance of dominant SRB and DNSOB rose from 3.95% to 10.79% and 2.22% to 9.95%, respectively. The sulfate-reducing process during anaerobic phase provided electron donors for subsequent autotrophic denitrification, making outlet NO3−-N concentrations reduced from 18.26 mg L−1 to 1.93 mg L−1. The sulfur activity batch test showed that 73.80%∼80.92% of sulfate were circulation utilized, and rest of them conversed to the gaseous H2S and S0. In addition to DNSOB, anoxic denitrifier of Halomonas (22.91%), aerobic denitrifier of Phaeodactylibacter (2.75%) and endogenous denitrifier of Defluviicoccus (3.18%) were also dominant heterotrophic bacteria (all halophilic or halotolerant) in the intermittent aeration SBBR. Batch activity tests and periodic laws have also verified the existence of corresponding denitrification pathways. This study shows that the enrichment of special halophilic functional bacteria with multiple nitrogen removal pathways is a good idea for the efficient treatment of high-concentrated hypersaline industrial wastewater.

Proceso de granulación y mecanismo de lodo granular aeróbico bajo estrés salino en un reactor de secuenciación por lotes

The formation and characteristics of aerobic granular sludge (AGS) under different operational conditions in a sequencing batch reactor (SBR), designed to treat Mustard tuber wastewater (MTW, characterized as saline wastewater), had been investigated in this study. Morphology and structure during granulation were determined using a microscope with digital camera and scanning electron microscope (SEM). Granules formed in the reactors could be classified as zoogloea granules with a clear boundary outline and filamentous granules with mycelia bestrewing boundary. Zoogloea granules, cultivated in reactor R1 and R2, were with higher density than filamentous granules, cultivated in reactor R3, and consequently had a higher settling velocity. Results showed that divalent metal ions such as Ca2+ and Mg2+ with phosphate in inflow could transform into precipitates, serving as crystal nucleus and carriers for granulation. Moreover, appropriate organic loading, hydrodynamic

High-efficiency salt, sulfate and nitrogen removal and microbial community in biocathode microbial desalination cell for mustard tuber wastewater treatment

Considering there is no study involving simultaneous salt, sulfate and nitrogen removal from high-salinity mustard tuber wastewater (MTWW), biocathode microbial desalination cell (BMDC) was first constructed and used to treat MTWW. The results showed that 97.4% of salt, 99.7% of sulfate and 99.8% of nitrogen could be removed from MTWW. The relative abundances of electrgenic bacteria in anode and cathode were 15.95% and 15.10%, respectively, which greatly promoted the electricity generation and desalination. The bacteria involved in sulfate reduction in anode were the dominant population, with relative abundance of 13.94%. Microbial community analysis of cathode biofilm indicated that autotrophic nitrification-anaerobic denitrification, electrochemical reduction and anaerobic ammonium oxidation might coexist for high-efficiency nitrogen removal. Besides, the BMDC showed stable power output for 150 days. These findings provide a promising approach for efficient treatment of MTWW.

Electricity generation, salinity, COD removal and anodic biofilm microbial community vary with different anode CODs in a microbial desalination cell for high-salinity mustard tuber wastewater treatment.

A three-chamber microbial desalination cell (MDC) was constructed for high-salinity mustard tuber wastewater (MTWW) treatment. The effect of anode COD on electricity generation, salinity, COD removal and the anodic biofilm microbial community in MDC for the MTWW treatment was investigated. The results showed that electricity generation was better when the anode COD was 900 mg L−1versus when it was 400 or 1400 mg L−1. The ionic strength and conductivity of the anolyte were higher than those at 400 mg L−1; thus, the ohmic internal resistance was lower. In addition, the mass transfer internal resistance was lower than that at 1400 mg L−1, which made the system internal resistance the lowest; consequently, the voltage and power density were the highest. The output voltage, power density and coulombic efficiency of the 1000 Ω external resistors were 555 mV, 3.03 W m−3 and 26.5% ± 0.4%, respectively. Desalination was the highest when the anode COD was 400 mg L−1. The lowest ionic strength and osmotic pressure of the anolyte resulted in the strongest osmosis, thereby producing the highest desalination rate; the desalination rate was 5.33 mg h−1. When MDC was coupled with the dual-chamber microbial fuel cell (MFC), the desalinated MTWW could be used as the anode substrate of the MFC; its high COD could be removed continuously, and the COD removal values were 86.2% ± 2.5%, 83.0% ± 2.0% and 84.3% ± 2.4%. High-throughput sequencing analysis indicated that hydrolytic and fermentative bacteria were the core anode bacteria of MDC. The abundances of electrochemically active bacteria in the anode biofilms of the three groups were 11.78% (400 mg L−1 COD), 14.06% (900 mg L−1 COD) and 13.68% (1400 mg L−1 COD). Therefore, the differences in anode CODs impacted the abundance of electrochemically active bacteria, which led to differences in electricity generation performances.

Electricity generation and microbial community in long-running microbial fuel cell for high-salinity mustard tuber wastewater treatment

High-salinity mustard tuber wastewater (MTWW) was utilized to obtain effluent treatment and recover bio-energy simultaneously in a microbial fuel cell (MFC). Since the long-term performance of MFCs in MTWW remains unclear, this study examined electricity generation and the microbial community that developed over a 195-day test. The MFC produced electricity over the entire testing period, with stable power output obtained on days 32–120. In the stable phase, a maximum power density of 12.43 W·m−3 was observed, and the internal resistance, open circuit voltage, and columbic efficiency (CE) were 148 Ω, 756 mV and 36.7 ± 1.2%, respectively. Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) removal continuously increased to 89.0 ± 1.5% and 98.6 ± 2.0%, respectively, the maximum rates that were obtained at the end of the experiment, respectively. In addition, 16S rRNA gene sequencing analysis showed that hydrolytic/fermentative bacteria could be considered as the bioanode core microbiome, constituting 36.90% of the microbiome. Sulfate-reducing bacteria (SRB), including Dethiosulfovibrio, Thermovirga, Desulfovibrio, and Desulfuromonas, eventually outcompeted the exoelectrogens completely, causing an irreversible loss in CE. This study provides more ideas for treatment and utilization of high-salinity MTWW.

Simultaneous nutrient and carbon removal and electricity generation in self-buffered biocathode microbial fuel cell for high-salinity mustard tuber wastewater treatment

Mustard tuber wastewater (MTWW) was used as both anolyte and catholyte in biocathode microbial fuel cell (BMFC). The results showed simultaneous nutrient and carbon removal and electricity generation were realized in BMFC. Excellent Chemical Oxygen Demand (COD) removal occurred in both anode (>90%) and cathode (>91%). Concerning nutrient removal, it was mainly removed in cathode. The maximum total phosphorus (TP) removal could reach 80.8 ± 1.0% by biological action. Simultaneous nitrification and denitrification (SND) was realized in cathode. The bacteria involved in nitrification were Nitrosomonas and SM1A02. Oceanimonas and Saprospiraceae_uncultured (anaerobic denitrifier), Thauera, Stenotrophomonas, Flavobacterium and Marinobacter (aerobic denitrifier), and Thioalkalispira (autotrophic denitrifier) were responsible for denitrification. Considering slight variation of anode and cathode pH, it could be concluded that MTWW was adequately self-buffered when used as electrolyte. Furthermore, electricity generation decreased with cathodic dissolved oxygen (DO) declining. These findings provide a novel method for MTWW resourceful treatment.

Enhancement of Organic Matter Removal in an Integrated Biofilm-Membrane Bioreactor Treating High-Salinity Wastewater.

High salinity can strongly inhibit microbial activity and decrease the sedimentation ability of activated sludge. The combination of biofilm and membrane bioreactor is a practical approach towards effective removal of pollutants and low fouling rate. An integrated biofilm-membrane bioreactor (BMBR) treating mustard tuber wastewater was investigated. An average COD removal efficiency of 94.81% and ammonium removal efficiency of 96.84% were achieved at an organic load of 0.5 kg COD/(m3·d). However, the reactor showed a relatively low efficiency in total nitrogen and soluble phosphorus removal due to the lack of anaerobic environment. The increase of influent organic load resulted in a performance degradation because a balance between the degradation ability and pollution has been reached. Images of scanning electron microscopy revealed that halophilic bacteria were the dominant microbe in the system that leads to a loose sludge structure and declined settling properties. It was found that membrane fouling was the consequence of the interaction of microbial activities and NaCl crystallization.

Bacterial community structure in simultaneous nitrification, denitrification and organic matter removal process treating saline mustard tuber wastewater as revealed by 16S rRNA sequencing

A simultaneous nitrification, denitrification and organic matter removal (SNDOR) process in sequencing batch biofilm reactor (SBBR) was established to treat saline mustard tuber wastewater (MTWW) in this study. An average COD removal efficiency of 86.48% and total nitrogen removal efficiency of 86.48% were achieved at 30gNaClL−1 during 100days’ operation. The underlying mechanisms were investigated by PacBio SMRT DNA sequencing (V1–V9) to analyze the microbial community structures and its variation from low salinity at 10gNaClL−1 to high salinity at 30gNaClL−1. Results showed elevated salinity did not affect biological performance but reduced microbial diversity in SBBR, and halophilic bacteria gradually predominated by succession. Despite of high C/N, autotrophic ammonia-oxidizing bacteria (AOB) Nitrosomonas and ammonia-oxidizing archaea (AOA) Candidatus Nitrososphaera both contributed to ammonium oxidation. As salinity increasing, nitrite-oxidizing bacteria (NOB) were significantly inhibited, partial nitrification and denitrification (PND) process gradually contributed to nitrogen removal.

Optimization of membrane fouling process for mustard tuber wastewater treatment in an anoxic-oxic biofilm-membrane bioreactor

Membrane bioreactor (MBR) technology has previously been used by water industry to treat high salinity wastewater. In this study, an anoxic-oxic biofilm-membrane bioreactor (AOB-MBR) system has been developed to treat mustard tuber wastewater of 10% salinity (calculated as NaCl). To figure out the effects of operating conditions of the AOB-MBR on membrane fouling rate (KV), response surface methodology was used to evaluate the interaction effect of the three key operational parameters, namely time interval for pump (t), aeration intensity (UGr) and transmembrane pressure (TMP). The optimal condition for lowest membrane fouling rate (KV) was obtained: time interval was 4.0 min, aeration intensity was 14.6 m3/(m2￥h) and transmembrane pressure was 19.0 kPa. And under this condition, the treatment efficiency with different influent loads, i.e. 1.0, 1.9 and 3.3 kg COD m-3d-1 was researched. When the reactor influent load was less than 1.9 kg COD m-3d-1, the effluent could meet the third discharge standard of “Integrated Wastewater Discharge Standard”. This study suggests that the model fitted by response surface methodology can predict accurately membrane fouling rate within the specified design space. And it is feasible to apply the AOB-MBR in the pickled mustard tuber factory, achieving satisfying effluent quality.

Influence of organic loading rate on integrated bioreactor treating hypersaline mustard wastewater.

Mustard tuber wastewater is characterized by high salinity and high organic content that is potentially detrimental to the biological treatment system and affects the treatment efficiency accordingly. The experiment used the integrated bioreactor to reduce much of the organics in mustard tuber wastewater, and found the influence of organic loading rate on effluent chemical oxygen demand (COD) and phosphate (PO4 (3-) -P). Results showed that under the condition of 10-15°C, 6mg/L of dissolved oxygen, the reduction value of COD removal rate in anaerobic and aerobic area was 14.5% and 31.7% when the organic loading rate increased from 2.0 to 4.0kg COD/m(3) /day. Therefore, an integrated bioreactor should take 2.0kg COD/m(3) /day organic loading rate in mustard wastewater treatment if the effluent is expected to meet the third level of "Integrated Wastewater Discharge Standard" (GB 8978-1996).