Search

Organic matter (OM) recovery from sewage sludge is critical for sustainable development. Extracellular organic substances (EOS) are the main organic components of sludge, and the release of EOS from sludge is usually the rate-limiting step for OM recovery. However, a poor understanding of the intrinsic characteristics of binding strength (BS) of EOS usually restricts the release of OM from sludge. To reveal the underlying mechanism that how the intrinsic characteristics of EOS limit its release, in this study, the BS of EOS in sludge was quantitatively characterised by 10 rounds of energy input (E in ) with the same magnitude per round; the corresponding changes in the main components, floc structures and rheological properties of sludge after different numbers of E in were also explored. Results showed that relationships between the release of EOS and the main multivalent metals, median diameters, fractal dimensions, elastic modulus and viscous modulus in the linear viscoelastic region of sludge versus the number of E in , highlighted that the power-law distribution of BS in EOS was responsible for the occurrence state of organic molecules, stability of floc structures and maintenance of rheological properties. The result of hierarchical cluster analysis (HCA) further revealed three BS levels of the EOS in sludge, indicating that the release or recovery of OM from sludge occurred in three stages. To the best of our knowledge, this is the first study that explores the release profiles of EOS in sludge by repeated E in for assessing the BS. Our findings may provide an important theoretical basis for the development target methods about the release and recovery of OM from sludge., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Reliable and accurate oxygen-input control, which is critical to maintaining efficient nitrogen removal performance for partial nitritation-anammox (PN-A) process, remains one of the main operational difficulties. In this study, a novel, yet simple system (a simple process for autotrophic nitrogen-removal, SPAN) with precise oxygen-input control was developed to treat ammonium-rich wastewater via PN-A process. SPAN brings oxygen to biomass by circulating water and creating water spray (shower) at the water-air interface, and effectively balances the activities of core functional microorganisms through precise oxygen-input control. The oxygen-input rate is decided by the water circulation rate and shower rate and is measurable and predictable. Therefore, the required amount of oxygen for ammonium oxidation can be precisely delivered to the biomass by adjusting the circulation rate and shower rate. The results of two parallel SPAN reactors demonstrated that during long-term operation, the required oxygen input was precisely and reliably controlled. More than 99% of NH 4 + -N and 81% - 85% of total nitrogen were stably removed, with anammox bacteria contributing to more than 96% of total nitrogen removal. Anammox bacteria were efficiently enriched to the highest level among the key nitrogen-converting microbial groups, both in terms of abundance (8.17%) and nitrogen-conversion capacity, while ammonium oxidizing bacteria were well controlled to provide sufficient ammonium-oxidizing capacity. Nitrite oxidizing bacteria were maintained stable (relative abundance of 1.08%-1.88%) and their activity was effectively suppressed. This study provided a novel technology, SPAN, to precisely control oxygen input in PN-A system, and proved that SPAN was effective and reliable in achieving long-term high-efficiency nitrogen removal., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The influence of temperature (30-45℃) and ammonia-nitrogen volume load on the nitrification function and microbial community of activated sludge in an aerobic tank of a sewage treatment plant were investigated under simulated high-temperature stress in the summer. Meanwhile, the bioaugmentation effectiveness of the middle-temperature-enriched nitrifying sludge (with or without acclimation) was evaluated in two biological treatment systems under high-temperature shock. The results showed that the ammonium-nitrogen (NH 4 + -N) removal efficiency and the nitrifying bacteria content of the aerobic activated sludge at 30-40℃ were above 90% and up to 4.55% and decreased to 40% and 1.97% at 45℃, respectively. To quickly recover the nitrification function of the biological system under high-temperature shock in the summer, the middle-temperature-enriched nitrifying sludge was acclimated at 40℃ for 61 d and achieved (60±5) mg·(L·h) -1 nitrification activity. Then, its bioaugmentation efficiency was compared with that of the middle-temperature-enriched nitrifying sludge. In the bioaugmentation test, 10% of NH 4 + -N was removed in the reactor inoculated with 5% (volume fraction) of the acclimated nitrifying sludge, while the reactor needed inoculate with 10% (volume fraction) of the middle-temperature-enriched sludge to achieve the same removal efficiency. The results suggested that middle-temperature-enriched nitrifying sludge, after acclimating at 40℃, has a better enhancement effect under a high-temperature shocking load.

This study investigated the performance and microbial community dynamics of a start-up method for the partial nitritation-anammox (PN-A) process: start-up from return sludge in an intermittently aerated sequencing batch reactor (IASBR). The robustness of this PN-A IASBR system in achieving long-term efficient nitrogen removal was also investigated. Stable partial nitritation with nitrite accumulation ratio of about 80% was firstly achieved in the IASBR. Then, PN-A process with total nitrogen removal of up to 81.5% was established due to the thriving of anammox bacteria Candidatus Kuenenia resulting from the reduction of the aeration rate. Molecular analysis showed that both bacterial and archaeal communities shifted greatly throughout the start-up stage and the PN-A stage. Besides bacterial genus Nitrosomonas, ammonium-oxidizing archaea (AOA) Candidatus Nitrososphaera with a high abundance of 3.44% also contributed to partial nitritation. Nitrospira was effectively restrained (abundance <1.6%) while methanogens co-existed with the aerobic and anaerobic nitrogen-conversion microorganisms. This study showed that IASBR configuration was efficient in starting up the PN-A process from return sludge, maintaining long-term efficient nitrogen removal and triggering the thrive of AOA., (Copyright © 2018. Published by Elsevier B.V.)

Wastewater treatment plants (WWTPs) have been regarded as important point-sources of antibiotic resistance genes (ARGs) in aquatic environments. To investigate the distribution and removal of ARGs in WWTPs, a pharmaceutical wastewater treatment plant (PWWTP) and an integrated wastewater treatment plant (IWWTP) in a fine-chemical industrial park were chosen, and polymerase chain reaction (PCR) and real-time PCR techniques were used to determine the occurrence and abundances of ARGs along the treatment processes. Ten and fifteen ARGs were detected initially in the influents of PWWTP and IWWTP respectively, in which tetracycline and sulfonamide resistance genes were frequently reported, while dfrA13 was first reported in WWTPs. The most abundant ARGs in the influents were sul Ⅰ and sul Ⅱ , followed by dfrA13 , tetQ , floR , tetO , and tetW . The total ARGs increased by 0.21 log after the treatment by PWWTP, whose effluent contributed 0.87% to the inflow yet 5.05% to the total ARGs of IWWTP. Finally the total ARGs removed by IWWTP was 1.03 log, with the remaining ARGs then transported within the final effluent to the nearby coastal area. The authors concluded that the environmental and other impacts from the spread of ARGs on the microbial communities of the coastal environment needed further study.

A bio-electrochemical reactor (BER) operating at different cathode potentials ranging from -300 to -1000 mV (vs standard hydrogen electrode, SHE) was used to reduce adsorbable organic halogens (AOX) in pharmaceutical wastewater. Cathode polarization enriched the electron donor of the biological system. Thus, the AOX removal efficiency in the BER improved from 59.9% to 70.2%, and the AOX removal rate increased from 0.87 to 1.17 mg AOX/h when the cathode potential was reduced from -300 to -1000 mV with the addition of methyl viologen, a known redox mediator. The decrease of the cathode potential was also beneficial for methane production, and the inhibition of the methanogenic process enhanced the AOX removal. Additionally, cathode coulombic efficiency analysis demonstrated that the proportion of electrons used for AOX reduction decreases with decreasing potential, from 37.6% at -300 mV to 17.3% at -1000 mV, although the AOX removal efficiency improves., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Nitrifying activated sludge (NAS) was enriched in a membrane bioreactor (MBR) with pre-treated municipal wastewater and additional ammonium sulfate as the culture medium. The influences of temperature, dissolved oxygen (DO), ammonia nitrogen volumetric load, free ammonia (FA), and free nitrite (FNA) on the enrichment of NAS were investigated, the cost of the process was evaluated, and then NAS's application in enhancing a wastewater biological treatment system against ammonia shocking loads was attempted. The results showed that after 182 days of cultivation in an MBR, NAS had a nitrification activity of 98.41 mg·(L·h) -1 , which was 30-times higher than that of the seeding sludge. The yield of NAS was 14.96 mg·(L·d) -1 , costing 3.52 Yuan for 1 kg. Temperature was found to be a key factor affecting the sludge nitrification activity. The sludge nitrification activity was decreased to 1/3 of the maximum value at temperatures below 15.0℃, while lowering the ammonium volumetric load retarded the decrease in the sludge nitrification activity to some extent. In addition, dissolved oxygen deficiency resulted in nitrite accumulation, and thereby slowed down the NAS enrichment rate. The enriched NAS was then applied to a wastewater biological treatment pilot equipment, which had just been exposed to an ammonium shocking load. The removal rate of ammonia nitrogen in the biological system increased from 29.4% to 88.4% after 2.0% of NAS was inoculated. The enhanced biological system retained ammonia removal rates of as high as 99.0%, even as the temperature dropped to 13.3℃±1.6℃ afterwards. The above pilot-experiment results suggested that enriched nitrifying sludge is suitable for quickly increasing the start-up or recovery rates of the nitrifying function in a biological system.

A lab-scale intermittently aerated sequencing batch reactor (IASBR) was applied to treat anaerobically digested swine wastewater (ADSW) to explore the removal characteristics of veterinary antibiotics. The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand (COD) volumetric loadings, solid retention times (SRT) and ratios of COD to total nitrogen (TN) or COD/TN. Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics. Mass balance analysis revealed that greater than 60% of antibiotics in the influent were biodegraded in the IASBR, whereas averagely 24% were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium. Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand (COD) volumetric loadings, which could achieve up to 85.1%±1.4% at 0.17±0.041kgCOD/m -3 /day, while dropped to 75.9%±1.3% and 49.3%±12.1% when COD volumetric loading increased to 0.65±0.032 and 1.07±0.073kgCOD/m -3 /day, respectively. Tetracyclines, the dominant antibiotics in ADSW, were removed by 87.9% in total at the lowest COD loading, of which 30.4% were contributed by sludge sorption and 57.5% by biodegradation, respectively. In contrast, sulfonamides were removed about 96.2%, almost by biodegradation. Long SRT seemed to have little obvious impact on antibiotics removal, while a shorter SRT of 30-40day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge. Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work., (Copyright © 2017. Published by Elsevier B.V.)

A membrane bioreactor (MBR) was used to treat ciprofloxacin (CIP)-contaminated artificial wastewater. The pollutant removal performance and the microbial community structure of the MBR were studied at three different CIP dosages (0 mg·L -1 , 5 mg·L -1 , and 10 mg·L -1 ). The results showed that the sludge concentration in the reactor decreased and then levelled off as the dosage of CIP was increased from 0 mg·L -1 to 5 mg·L -1 and further to 10 mg·L -1 . The mean removal of TOC and COD decreased from 98.40% and 97.80% to 84.20% and 94.10%, respectively, indicating that the CIP negatively influenced the organic removal but the effect was minor. In contrast, the ammonium removal was greatly influenced by the dosage of CIP. When the CIP dosage increased from 0 mg·L -1 to 5 mg·L -1 and further to 10 mg·L -1 , the ammonium removal efficiency decreased from 96.91% to 84.14% and then to 77.80%, and the activity of Nitrosomonas , Alcaligenes , Nitrospira , and Nitrobacter were greatly inhibited. The CIP removal initially increased and then decreased. The mass balance revealed that the removal of CIP in the MBR was principally attributed to biodegradation and sludge adsorption, which accounted for 30.13% and 0.25%, respectively, at a CIP dosage of 5 mg·L -1 and 7.55% and 1.81% at a CIP dosage of 10 mg·L -1 .

In this study, nitrifying bacteria were enriched in a membrane bioreactor (MBR, R1) and their bioaugmentation effectiveness was evaluated in another two MBRs (R2 and R3). Nitrifying activated sludge (NAS) with high nitrification activity of up to 3,000 mg-N/(L·d) -1 was successfully enriched in R1. The results showed that chemical oxygen demand concentration of 100-200 mg/L had no negative effect on NAS enrichment but reduced the ratio of bacterial nitrifiers. Moreover, the cell concentration of nitrifying bacteria in NAS, which was 3.1 × 10 11 cells/L, was similar to that of the commercial bacterium agent. For the bioaugmentation test, the reactor inoculated with 14% NAS achieved a 23% higher NH 4 + -N removal efficiency than that of the uninoculated reactor. Along with the improvement of nitrification performance, the bacterial nitrifiers abundance and microbial richness remarkably increased after bioaugmentation. These results suggested that the MBR system could efficiently enrich nitrifying bacteria using organic carbon containing culture medium, and potentially act as a side-stream reactor to enhance the nitrification function of the wastewater treatment plant.

Digested piggery wastewater(DPW) contains high concentrations of nitrogen and phosphorus which could be used as a cost-effective culture medium for Spirulina platensis . However, Spirulina platensis would be limited by many factors in the complex composition of DPW, especially the high concentration of ammonium. In this paper, a traditional sequencing batch reactor(SBR) was used to remove these inhibitors in DPW. The retention of nitrate and nitrite in the effluent, which was used as nitrogen source for cultivating Spirulina platensis , was studied at different ratios of chemical oxygen demand(COD) to total nitrogen(TN) in the influent. By comparing the growth of Spirulina platensis in the related effluents, the operation condition of SBR was optimized. The lab-scale cultivation results showed that Spirulina platensis possessed a high biomass yield of 0.084 g·(L·d) -1 in the effluent when the COD/TN ratio of SBR influent was 3.0. In particular, the concentrations of ammonium, nitrate and nitrite in the effluent were 51.2 mg·L -1 , 91.6 mg·L -1 and 213.1 mg·L -1 , respectively. Furthermore, the aforementioned effluent was also used to culture Spirulina platensis in a 120 L outdoor raceway pond, and the growth rate of Spirulina platensis reached(0.075±0.003)g·(L·d) -1 after 10-day culture. The protein content of Spirulina platensis was approximately 60% and the removal efficiency of ammonium was 99%. This study provides an alternative method for the utilization of DPW.

In this study, a lab-scale biological anaerobic/anaerobic/anoxic/membrane bioreactor (A 3 -MBR) was designed to treat wastewater from the ethanol fermentation of food waste, a promising way for the disposal of food waste and reclamation of resources. The 454 pyrosequencing technique was used to investigate the composition of the microbial community in the treatment system. The system yielded a stable effluent concentration of chemical oxygen demand (202±23mg/L), total nitrogen (62.1±7.1mg/L), ammonia (0.3±0.13mg/L) and total phosphorus (8.3±0.9mg/L), and the reactors played different roles in specific pollutant removal. The exploration of the microbial community in the system revealed that: (1) the microbial diversity of anaerobic reactors A 1 and A 2 , in which organic pollutants were massively degraded, was much higher than that in anoxic A 3 and aerobic MBR; (2) although the community composition in each reactor was quite different, bacteria assigned to the classes Clostridia, Bacteroidia, and Synergistia were important and common microorganisms for organic pollutant degradation in the anaerobic units, and bacteria from Alphaproteobacteria and Betaproteobacteria were the dominant microbial population in A 3 and MBR; (3) the taxon identification indicated that Arcobacter in the anaerobic reactors and Thauera in the anoxic reactor were two representative genera in the biological process. Our results proved that the biological A 3 -MBR process is an alternative technique for treating wastewater from food waste., (Copyright © 2016. Published by Elsevier B.V.)

An intermittently aerated sequencing batch reactor (IASBR) and a traditional sequencing batch reactor (SBR) were respectively used for treating digested piggery wastewater, and the pollutant removal performance was studied at different ratios of chemical oxygen demand (COD) to total nitrogen (TN) in the influent and different loading rates. The results showed that the pollutant removal rates in the IASBR were much higher than those in the SBR. Under influent COD/TN of about 2.2 and NH 4 + -N loading of (0.12±0.04) kg·(m 3 ·d) -1 , the removal rates of NH 4 + -N, TN and TOC in the IASBR were 97.2%±4.4%, 81.5%±7.5% and 88.5%±2.4%, respectively, higher than the corresponding rates of 78.3%±19.6%, 79.8%±4.9% and 86.6%±3.2% in the SBR. As the NH 4 + -N loading was increased to (0.18±0.02) kg·(m 3 ·d) -1 , the removal rates of NH 4 + -N, TN and TOC in the IASBR were slightly decreased to 92.4%±7.3%, 77.5%±5.3% and 86.4%±2.2%, but still higher than the corresponding values of 78.1%±15.4%, 61.8%±11.2% and 81.8%±5.6% in the SBR. As the NH 4 + -N loading was remained at (0.20±0.01) kg·(m 3 ·d) -1 , but the influent COD/TN ratio was increased to about 3.0, the pollutant removal rates in both IASBR and SBR were increased, compared to those at influent COD/TN ratio of 2.2.The removal rates of NH 4 + -N, TN and TOC in the IASBR were 99.6%±0.2%, 91.5%±2.9% and 92.0%±0.9%, respectively, higher than the corresponding rates of 90.2%±1.4%, 83.0%±1.9% and 90.2%±0.5% in the SBR. Based on the above, the IASBR was more efficient in TN and ammonium removal and more shocking load resistant, and therefore was more feasible than SBR for treating low COD/TN ratio wastewaters such as the digested piggery wastewater.

Removal of conventional pollutants as well as genotoxicity was studied along a multistage A/O process, which was based on the monitoring data in a Municipal Wastewater Treatment Plant (MWWTP) of Yixing City. The results showed that the multistage A/O process removed (67.3±7.0)% of COD, (93.7±1.5)% of NH 4 + -N, (65.3±7.9)% of TN and (60.0±18.7)% of TP, respectively, which played a dominant role in the removal performance of the whole wastewater treatment process. The multistage A/O process showed significant ability to reduce alkanes, halogenated hydrocarbons and alcohols in the municipal wastewater, while it failed to remove the aromatic proteins which were the main fluorescent substances of this wastewater. Furthermore, the process removed 82.8% genotoxicity from its influent. Low organic load, single-phase influent and undesirable carbon source feeding pattern, which caused the downstream A/O stages being not fully utilized, were considered as the predominant reasons for the relatively low performance of the multistage A/O process. Multi-phase feeding and adjusting carbon source feeding pattern were thereby proposed. The results were considered to be helpful for improving the operational performance of the MWWTP and useful for performance evaluation of MWWTPs with similar process.

This study aimed to remove AOX (adsorbable organic halogens) with Fenton oxidation from activated sludge in a chemical pharmaceutical industry. The influences of H 2 O 2 dosage, Fe 2+ dosage and reaction time were investigated, based on which the reaction conditions for AOX removal were optimized, and the reaction mechanism was discussed. The optimized reaction conditions were as follows:0.90 mol·L -1 of H 2 O 2 , 0.045 mol·L -1 of Fe 2+ [ n (Fe 2+ ): n (H 2 O 2 ) of 1:20] and reaction time of 2 h. Under the optimized conditions, 70.7% of AOX in the sludge and 78.5% of AOX in the supernatant were removed. GC-MS analysis revealed that eleven organic halides were detectable in the original sludge. After Fenton reaction, only three organic halides were detectable, and their peak areas were reduced by 40%-50%. Toxic and hazardous non-AOX organic matters such as xylene, diisobutyl phthalate were also effectively removed.

Stability of short-cut nitrification nitrogen removal performance was studied in a step-feeding, intermittently aerated sequencing batch reactor (IASBR) at 30°C to treat digested piggery wastewater. Results showed that the nitrogen removal was greatly influenced by the ratio of chemical oxygen demand (COD) to total nitrogen (TN) in the influent. Nitrite nitrogen kept accumulating up to 800 mg · L⁻1 when the influent COD/TN ratio was 0.8 ± 0.2, and the removal rates of TN, ammonium nitrogen and total organic carbon (TOC) were only 18.3% ± 12.2%, 84.2% ± 10.3% and 60.7% ± 10.7%, respectively. By contrast, as the influent COD/ TN ratio was increased to 2.4 ± 0.5, the accumulated concentration of nitrite nitrogen sharply decreased from 800 mg · L⁻¹ to below 10 mg-L⁻¹, and the removal rates of TN, ammonium nitrogen and TOC were increased to over 90%, 95% and 85%, respectively. Gradually shortened hydraulic retention time ( HRT) reveales that the ammonia load is a restricting factor for nitrogen removal. The ammonia load should be controlled at no more than 0.30 kg · (m³ · d) ⁻¹, or else, the removal rates of TN, ammonium and TOC would be greatly decreased. The nitrite accumulation rate over the whole run was 74.6%-97.8% and the TN removal rate in the stable phase was over 90%. With efficient and stable short-cut nitrification-denitrification in a low COD/TN, moreover, and unnecessary for addition of alkaline, IASBR shows great advantage for treating wastewater with high concentration of ammonia while low COD/TN ratio.

The removal performance of 11 veterinary antibiotics in piggery wastewater and their accumulation in the activated sludge were studied in an intermittent aeration membrane bioreactor (IAMBR) at different COD/TN ratios and organic loads. The results showed that both antibiotics and chemical oxygen demand (COD) were efficiently removed at hydraulic retention time (HRT) of no less than five days and COD/TN ratio of 2.1, the removal rate was (79.1 ± 0.7)% for total antibiotics and was (88.4 ± 1.4)% for COD. As HRT was shortened to three days, the removal rate of COD was little changed but the removal rate of total antibiotics was significantly decreased. As COD/TN decreased from 2.1 to 0.7, the removal rate of total antibiotics was little changed, but the COD removal rate was significantly decreased. Antibiotics of tetracycline and quinolone species kept accumulating in the sludge at long SRT, and the accumulation amount was decreased with shorter SRT. The concentration and composition of antibiotic in the sludge were influenced by the raw wastewater.

Selecting six large-scale dyeing factories and four large-scale dyestuff chemical factories in the well-developed Yangtze River Delta region, this study aimed to investigate the AOX pollution status in the raw wastewater as well as in the activated sludge treatment system. The components of AOX were characterized by GC-MS. Results showed that AOX concentration was low in wastewater from the six dyeing enterprises, ranging 0. 15-1. 62 mg.L-1 in the raw wastewater and 0. 06-1. 30 mg.L-1 in the biologically treated effluent. All the biologically treated effluent met the emission limits of 8 mg.L-1 in the Discharge Standard of Water Pollutants for Dyeing and Finishing of Textile Industry. Sludge in five factories with AOX was below 621 mg.kg-1, only one factory was with high AOX concentration of 3 280 mg.kg-1. By comparison, AOX concentration greatly varied between the wastewater from dyestuff chemical factories, was 1. 70 mg.L-1 to 78. 72 mg.L-1 in the raw wastewater and was 1. 88 mg.L-1 to 33. 11 mg.L-1 in the biologically treated effluent. AOX concentration in the activated sludge was as high as 960-2,297 mg.kg-1. Chlorobenzenes, chloronitrobenzenes, chloroanilines, chlorine nitroanilines and halophenols were typical TOX components detectable in the dyestuff chemical wastewater. Halophenols and chlorine nitroanilines could be efficiently removed. Single chloroanilines and single chloronitrobenzenes seemed to be easier removable than polychlorinated anilines and polychlorinated nitrobenzenes. Polychlorinated benzenes were also easily removal but the products chlorobenzene was hard to remove.

With high concentrations of chemical oxygen demand (COD) and ammonium while low ratio of COD to total nitrogen (TN), digested piggery wastewater is difficult to treat using conventional biological methods. In this study, a biofilm membrane bioreactor (BF-MBR) and a traditional type of membrane bioreactor (MBR) were parallel operated to treat digested piggery wastewater, and the pollutant removal performance were compared at influent COD/TN ratios of 1. 0 ± 0. 2 and 2. 3 ± 0. 4, respectively. The results showed that the effluent quality in both reactors was poor and unstable when the influent COD/TN ratio was 1. 0 ± 0. 2. The effluent quality and stability were greatly improved as the influent COD/TN ratio was increased to 2. 3 ± 0. 4. The removal rates of COD and ammonium were respectively 92. 3% ± 2. 4% and 97. 5% ± 4. 1% in BF-MBR, slightly higher than 91. 9% ± 1. 5% and 91. 2% ± 14. 0% in MBR. Benefited from the biofilm, 36. 7% ± 19. 5% of TN and 54. 0% ± 18. 9% of TP were removed by BF-MBR, significantly higher than the respective values of 19. 2% ± 12. 4% and 29. 0% ± 18. 1% by MBR. Moreover, BF-MBR consumed less than 40% of the alkaline chemicals as MBR. BF-MBR was considered more suitable for treatment of digested piggery wastewater due to its better pollutant removal performance and low consumption of alkaline.

An Arthrospira platensis strain ZJWST-S1 was isolated in Jiaxing City, China, which proved able to proliferate quickly in undiluted digested piggery wastewater (DPW), and the protein content in the algal biomass was high. Single factor experiments showed that the strain was able to quickly grow in a Zarrouk medium as the dosage of sodium bicarbonate, nitrate-nitrogen and phosphate-phosphorus was not less than 4.0 mg·L(-1), 40 mg·L(-1) and 10 mg·L(-1), respectively. No growth inhibition was observed when the culturing medium contained nitrite nitrogen of 0-120 mg·L(-1) and ammonium nitrogen of below 20 mg·L(-1). Five runs of semi-continuous cultivation with DPW as the culturing medium in a 250 L raceway pond showed that the biomass yield in a 9-day semi-continuous culturing was up to 45.2-64.7 g·m(-2)·d(-1), higher than the yields obtained by other researchers, and the crude protein content in biomass was over 50%, meeting the national animal feed grade standard. Total nitrogen (TN) and total phosphorus (TP) were removed from DPW at a rate of 10.9-14.0 mg·L(-1)·d(-1) and 1.3-1.8 mg·L(-1)·d(-1), respectively. The mass balance revealed that 80-93% of TN and 84-98% of TP reduced from DPW were converted to A. platensis biomass.

A pilot-scale process with the capacity of 15 t x d(-1) was applied for treatment of the secondary biological effluent from a dyeing industrial park wastewater treatment plant. We studied the variation of pollutants along the height of two media biological aerated filter (BAF), investigated the feasibility of the cheaper and lighter suspended media to substitute activated carbon. The results showed that while the influent average COD and color were 50.2 mg x L(-1) and 58 times, the effluent average COD and color of activated carbon and suspended media BAF were 35.0 mg x L(-1), 18 times and 44.3 mg x L(-1), 26 times, and both of the effluent met the first level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002), while it met the first level A criteria at the height of 2 400 mm in suspended media BAF, higher than the height of 1 800 mm in activated carbon BAF. The removal variation of color, TN and ammonia along the height of suspended media BAF is similar to the activated carbon BAF, but with a low removal efficiency of COD, mainly related to its less biomass. Therefore, suspended media to substitute activated carbon is feasible to the wastewater treatment plant, but the size and material of the media still need to be optimized, and to enhance the biomass, the hybrid process of suspended media with activated carbon BAF may be used to reduce the cost if it is necessary.

The swine waste pretreated with coagulation sedimentation was used for the outdoor pilot-scale cultivation of Spirulina platensis isolated from digested piggery wastewater (DPW) in a raceway pond. The growth of S. platensis and removal of nitrogen/ phosphorus were studied, moreover, the conversion efficiency of total nitrogen (TN) or total phosphorus (TP) from DPW to S. platensis was calculated. On this basis, the existing problems and countermeasures during outdoor pilot-scale culture were analyzed and summarized combined with the laboratory research. We conducted 6 batches culture experiments, only 3 of which could reach the S. platensis harvest requirements (D560 >0. 8). Meanwhile, the 3 successful batches achieved removal of COD, ammonia nitrogen, TN, TP with corresponding 28. 6% -48. 5% , 0.4% -48. 5% , 41. 8% -48. 6% , 14. 3% -94. 5% , and the conversion efficiency of TN or TP from DPW to S. platensis reached 12. 1% -98. 5% , 21.2% -83.7% , respectively. High concentration of ammonia nitrogen and insect attack of remaining egg hatching in the pretreated swine waste were the main factors to cause the slow-growing of the 3 batches of S. platensis. Therefore, it is highly necessary for the removal of ammonia nitrogen with biological treatment technology and insect eggs with membrane to achieve a stable high productivity.

The bacterial strain Paracoccus denitrificans W12, which could utilize pyridine as its sole source of carbon and nitrogen, was added into a membrane bioreactor (MBR) to enhance the treatment of a pharmaceutical wastewater. The treatment efficiencies investigated showed that the removal of chemical oxygen demand, total nitrogen, and total phosphorus were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of pyridine was obtained in the bioaugmented reactor. When the hydraulic retention time was 60 hr and the influent concentration of pyridine was 250-500 mg/L, the mean effluent concentration of pyridine without adding W12 was 57.2 mg/L, while the pyridine was degraded to an average of 10.2 mg/L with addition of W12. The bacterial community structure of activated sludge during the bioaugmented treatment was analyzed using polymerase chain reaction -denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the W12 inoculum reversed the decline of microbial community diversity, however, the similarity between bacterial community structure of the original sludge and that of the sludge after bioaugmentation decreased steadily during the wastewater treatment. Sequencing of the DNA recovered from DGGE gel indicated that Flavobacteriaceae sp., Sphingobium sp., Comamonas sp., and Hyphomicrobium sp. were the dominant organisms in time sequence in the bacterial community in the bioaugmented MBR. This implied that the bioaugmentation was affected by the adjustment of whole bacterial community structure in the inhospitable environment, rather than being due solely to the degradation performance of the bacterium added.

The potential biotoxicity to the environment should be addressed during wastewater treatment. In this study, biotoxicity of coking wastewater effluent from MBR, Fenton, electro-Fenton and coagulation treatment processes was evaluated using embryos and larvae of Japanese medaka (Oryzias latipes). The acute toxicity based on 96-h larval mortality as well as the chronic toxicity based on embryo hatching, larvae swim-up failure, growth, and sexual ratio were determined. The results showed that different treatment processes have various biotoxicity levels. The acute toxicity of Fenton and electro-Fenton effluents was much higher than that of MBR and coagulation. For the chronic toxicity, the effluent of the Fenton/electro-Fenton process displayed lower embryo hatching, larvae survival and growth in comparison with the effluents of MBR and coagulation. No endocrine disruption was detected in MBR, Fenton and electro-Fenton effluents, but was contained in the coagulation effluent. The biotoxicity test indicated that the effluent of MBR was very safe for the environment. The toxicological indices were necessary for ecological safety maintenance in the industrial wastewater treatment.

A pilot-scale hybrid process of ozone and biological aerated filters (BAF) with the capacity of 36 t x d(-1) was applied for advanced treatment of the secondary biologically effluent from a dyeing and tannery park wastewater treatment plant. The pollutants removal performance along the height of different medias BAFs were investigated. The results showed that the average COD and color were 55.4 mg x L(-1) and 12.6 times at the height of 1500 mm in activated carbon BAF, and were 55.6 mg x L(-1) and 9.4 times at the height of 1 800 mm in composite BAF, both of the effluent at each height met the first level B criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002). Along the height of ceramist BAF, the COD and color were seldom removed. In activated carbon BAF and composite BAF, COD and ammonia nitrogen were both greatly decreased at the height of 1 200 mm, then decreased slowly. The biomasses simultaneously reached the maximum at the height of 900 mm in activated carbon, composite and ceramist BAF, with the maxims of 30.69, 28.87 and 15.94 nmol x g(-1), respectively.

The influence of mixed liquor suspended solids (MLSS), soluble microbial product (SMP), extracellular polymeric substance (EPS), colloidal particles and other factors contributed to membrane fouling was analyzed in this pilot test by membrane bioreactor (MBR) process for the leather printing and dyeing industrial park mixed wastewater treatment. The results showed that slight membrane fouling occurred after 120-day experiment with an observable increase in membrane resistance R20 from 1.5 x 10(12) m(-1) to 1.8 x 10(12) m(-1). Also, a linear correlation was found between the proportion of colloidal particles concentration in TOC of MBR former solution and membrane filtration resistance change. However, the change of MLSS, SMP, EPS and other factors was not correlated with the membrane filtration resistance change. Therefore, the colloidal particle was considered to be the main factor causing membrane fouling, which attached to the membrane surface and deposited to block the membrane pore.