Biological improvement on combined mycelial pellet for aniline treatment by tourmaline in SBR process

As a biomass carrier, mycelial pellet of Aspergillus niger Y3 was used to immobilize the aniline-degrading bacterium Acinetobacter calcoaceticus JH-9 and the mix culture of the COD rapid degrading bacteria in this study. Tourmaline was added to this system in order to improve the aniline removal performance using combined mycelial pellet. Flask experiments were performed to investigate the promotion mechanism. The results showed that the start-up time was shorted from 7 cycles to only 1 cycle. The aniline and COD concentration in effluent were much lower in the tourmaline-adding system. It was suggested that tourmaline could enhance the number and activity of the aniline-degrading bacteria immobilized on the mycelial pellet. Therefore, the performance of mycelial pellet as a biomass carrier could be improved by tourmaline.     

Nitrogen removal from wastewater with a low COD/N ratio at a low oxygen concentration

The goal of the study was to determine the effectiveness of nitrification and denitrification and the kinetics of ammonia removal from a mixture of wastewater and anaerobic sludge digester supernatant in an SBR at limited oxygen concentration. In addition, the COD removal efficiency and sludge production were assessed.In the SBR cycle alternating aerobic and anaerobic phases occurred; in the aeration phase the dissolved oxygen (DO) concentration was below 0.7 mg O₂/L. The low DO concentration did not inhibit ammonia oxidation-nitrification and the efficiency was ca. 96-98%. However, a relatively high COD concentration in the effluent was detected. The values of K_m and V_max, calculated from the Michaelis-Menten equation, were 43 mg N-NH₄/L and 15.64 mg N-NH₄/L h, respectively. Activated sludge production was almost stable (0.62-0.66 g MLVSS/g COD). A high net biomass production resulted from a low specific biomass decay rate of 0.0015 d⁻¹.     

Nitrogen removal via simultaneous partial nitrification,anammox and denitrification (SNAD) process under high DO condition

The simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating domestic wastewater was investigated in a sequencing batch reactor (SBR). The SBR was operated with air flow rate of 500 L h^?1 at 30 °C. Domestic wastewater was used as influent and Kaldnes rings were used as biomass carriers. In the beginning, long aeration condition was implemented to cultivate nitrification biofilm. Afterwards, intermittent aerobic condition was conducted during the cycle operation. The influent organic matter loading rate was improved by reducing the aeration and mixing times. Consequently, when the SNAD biofilm reactor was fed with the organic matter loading rate of 0.77 (kg COD m^?3 d^?1), the bio-bubbles appeared in the reactor and the total inorganic nitrogen (TIN) removal efficiency decreased. After the organic matter loading rate decreased to 0.67 (kg COD m^?3 d^?1), the reactor showed excellent nitrogen removal performance. The TIN removal efficiency varied between 80 and 90 %, and the average TIN removal loading rate was 0.22 (kg TIN m^?3 d^?1). Additionally, the scanning electron microscope (SEM) observation confirmed that the anammox bacteria located in the inner part of the carriers. Finally, the microbial community analysis of 16S rRNA gene cloning revealed that the anammox bacteria on the carriers consisted of three main genuses: Candidatus Brocadia sp., Candidatus Brocadia caroliniensis and Candidatus Brocadia fulgida.     

Effect of aspartate and glutamate on the fate of enhanced biological phosphorus removal process and microbial community structure

This study investigated the fate of enhanced biological phosphorus removal (EBPR) and changes in microbial speciation in a sequencing batch reactor (SBR) fed with aspartate and glutamate. It involved SBR operation for 288 days, batch tests for observation of metabolic functions together with microscopic and phylogenetic analyses. Polyphosphate accumulating organisms (PAOs) were observed in abundance with complete removal of phosphorus. Fluorescence in situ hybridization (FISH) combined with 4′,6-dia-midino-2-phenylindole (DAPI) staining confirmed the accumulation of polyphosphate by Rhodocyclus-related and Actinobacterial PAOs. Aspartate seemed to favor the competitive growth of Rhodocyclus-related PAOs since EBPR population used the common biochemical pathways followed by Rhodocyclus-related PAOs in the aspartate fed batch tests. In the glutamate fed batch reactors, however, Actinobacterial PAOs appeared to be competitively selected which explains the lower levels of PHA generation. Even though operational conditions did not change, effective EBPR could not be maintained during the latter part of the study.     

甘蔗纤维固定灵芝菌丝及其在液体发酵中的应用

以甘蔗纤维作为灵芝菌丝固定载体,通过扫描电子显微镜观察确定载体固定时间,通过液体发酵灵芝菌丝球大小形态、生物量、胞外多糖和胞外三萜含量确定载体形状、大小与数量。结果表明,灵芝菌丝在载体上固定时间为7d,载体为1.5cm×1.5cm（直径×高度）的圆柱体小块（Y1.5）,接种数量6块,可连续稳定发酵7代。以甘蔗纤维固定发酵制备灵芝液体发酵种子,发酵后菌丝球大小均一,生物量、胞外多糖含量和三萜含量分别提高78%、84%和60%。     

A bio-oxidation study of methanol synthetic wastewater using the SBR

Bio-oxidation and biomass generation in a laboratory-scale sequencing batch reactor (SBR) were investigated. This paper presents the results obtained from an SBR treating a synthetic wastewater used to simulate a pharmaceutical wastewater. Nutrient removal and biokinetics of the SBR process, as well as dissolved oxygen and pH variations during bio-oxidation, were discussed. COD and BOD removal efficiencies were good. System stability was achieved within 2 weeks of each change of feed strength. The 48-h cycle adopted was found to be sufficient to force the biomass into endogenous respiration, hence controlling the excess biomass formed through assimilation of the feed's organic carbon. Although the ammonia-nitrogen level in the feed was high, nitrification was not observed. Track monitoring of DO and pH was found to provide good indications of the completion of bio-oxidation.     

Effect of COD/N ratio on cultivation of aerobic granular sludge in a pilot-scale sequencing batch reactor

Aerobic granular sludge was successfully cultivated with the effluent of internal circulation reactor in a pilot-scale sequencing batch reactor (SBR). Soy protein wastewater was used as an external carbon source for altering the influent chemical oxygen demand/nitrogen (COD/N) ratios of SBR. Initially, the phenomenon of partial nitrification was observed and depressed by increasing the influent COD/N ratios from 3.32 to 7.24 mg/mg. After 90 days of aerobic granulation, the mixed liquor suspended solids concentration of the reactor increased from 2.80 to 7.02 g/L, while the sludge volumetric index decreased from 105.51 to 42.99 mL/g. The diameters of mature aerobic granules vary in the range of 1.2 to 2.0 mm. The reactor showed excellent removal performances for COD and $ {\text{NH}}_4^{ + }{\text{ - N}} $ after aerobic granulation, and average removal efficiencies were over 93% and 98%, respectively. The result of this study could provide further information on the development of aerobic granule-based system for full-scale applications.     

Simulated acid azo dye (Acid black 210) wastewater treatment by periodic discontinuous batch mode operation under anoxic–aerobic–anoxic microenvironment conditions

Treatment of simulated acid azo dye (C.I. Acid black 210) wastewater was studied in periodic discontinuous batch mode operation employing sequencing batch reactor (SBR) with suspended growth configuration under anoxic–aerobic–anoxic microenvironment. The performance of the reactor was evaluated at two organic loading rates (0.56 kg COD/m³-day and 0.75 kg COD/m³-day) with a total cycle period of 24 h [fill phase: 30 min; react phase: 23 h; settle phase: 15 min; decant phase: 15 min] at room temperature. The performance of SBR was assessed by monitoring both COD and colour (OD-617 nm) concentrations. Periodic discontinuous batch mode operation feasibility for dye colour removal along with simultaneous substrate (COD) removal. The performance efficiency of the system was found to depend on the operating organic loading rate. Induced anoxic microenvironment during cycle operation and persistent anoxic microenvironment in the internal layer of suspended biomass may be probable reasons for dye mineralization/reduction. Rapid startup period and non-inhibited performance at higher loading rate are some of the advantages observed in the SBR operation.     

Treatment of APMP pulping effluent based on aerobic fermentation with Aspergillus niger and post-coagulation/flocculation

A novel two-stage biological/flocculation process was developed for treating the pulping effluent from the alkaline peroxide mechanical pulping (APMP) process. In the first biological stage, the aerobic fermentation by using Aspergillus niger can decrease the chemical oxygen demand (COD) by about 60% while producing about 7 g/l of solid biomass. In the second stage (post-coagulation/flocculation), the residual COD, turbidity and color, can be further decreased by using alum and polyacrylamide (PAM). The overall removal efficiencies of COD, color and turbidity from the APMP pulping effluent by the above two-stage biological-coagulation/flocculation process were 93%, 92% and 99%, respectively, under the conditions studied.     

Use of Stable-Isotope Probing, Full-Cycle rRNA Analysis, and Fluorescence In Situ Hybridization-Microautoradiography To Study a Methanol-Fed Denitrifying Microbial Community

A denitrifying microbial consortium was enriched in an anoxically operated, methanol-fed sequencing batch reactor (SBR) fed with a mineral salts medium containing methanol as the sole carbon source and nitrate as the electron acceptor. The SBR was inoculated with sludge from a biological nutrient removal activated sludge plant exhibiting good denitrification. The SBR denitrification rate improved from less than 0.02 mg of NO₃⁻-N mg of mixed-liquor volatile suspended solids (MLVSS)⁻¹ h⁻¹ to a steady-state value of 0.06 mg of NO₃⁻-N mg of MLVSS⁻¹ h⁻¹ over a 7-month operational period. At this time, the enriched microbial community was subjected to stable-isotope probing (SIP) with [¹³C]methanol to biomark the DNA of the denitrifiers. The extracted [¹³C]DNA and [¹²C]DNA from the SIP experiment were separately subjected to full-cycle rRNA analysis. The dominant 16S rRNA gene phylotype (group A clones) in the [¹³C]DNA clone library was closely related to those of the obligate methylotrophs Methylobacillus and Methylophilus in the order Methylophilales of the Betaproteobacteria (96 to 97% sequence identities), while the most abundant clone groups in the [¹²C]DNA clone library mostly belonged to the family Saprospiraceae in the Bacteroidetes phylum. Oligonucleotide probes for use in fluorescence in situ hybridization (FISH) were designed to specifically target the group A clones and Methylophilales (probes DEN67 and MET1216, respectively) and the Saprospiraceae clones (probe SAP553). Application of these probes to the SBR biomass over the enrichment period demonstrated a strong correlation between the level of SBR denitrification and relative abundance of DEN67-targeted bacteria in the SBR community. By contrast, there was no correlation between the denitrification rate and the relative abundances of the well-known denitrifying genera Hyphomicrobium and Paracoccus or the Saprospiraceae clones visualized by FISH in the SBR biomass. FISH combined with microautoradiography independently confirmed that the DEN67-targeted cells were the dominant bacterial group capable of anoxic [¹⁴C]methanol uptake in the enriched biomass. The well-known denitrification lag period in the methanol-fed SBR was shown to coincide with a lag phase in growth of the DEN67-targeted denitrifying population. We conclude that Methylophilales bacteria are the dominant denitrifiers in our SBR system and likely are important denitrifiers in full-scale methanol-fed denitrifying sludges.     

Effect of agitation speed on the morphology of Aspergillus niger HFD5A-1 hyphae and its pectinase production in submerged fermentation

AIM: To investigate the impact of agitation speed on pectinase production and morphological changing of Aspergillus niger(A. niger) HFD5A-1 in submerged fermentation. METHODS: A. niger HFM5A-1 was isolated from a rotted pomelo. The inoculum preparation was performed by adding 5.0 m L of sterile distilled water containing 0.1% Tween 80 to a sporulated culture. Cultivation was carried out with inoculated 1 × 107 spores/m L suspension and incubated at 30 ℃ with different agitation speed for 6 d. The samples were withdrawn after 6 d cultivation time and were assayed for pectinase activity and fungal growth determination. The culture broth was filtered through filter paper(Whatman No. 1, London) to separate the fungal mycelium. The cell-free culture filtrate containing the crude enzyme was then assayed for pectinase activity. The biomass was dried at 80 ℃ until constant weight. The fungal cell dry weight was then expressed as g/L. The 6 d old fungal mycelia were harvested from various agitation speed, 0, 50, 100, 150, 200 and 250 rpm. The morphological changing of samples was then viewed under the light microscope and scanning electron microscope.RESULTS: In the present study, agitation speed was found to influence pectinase production in a batch cultivation system. However, higher agitation speeds than the optimal speed(150 rpm) reduced pectinase production which due to shear forces and also collision among the suspended fungal cells in the cultivation medium. Enzyme activity increased with the increasing of agitation speed up to 150 rpm, where it achieved its maximal pectinase activity of 1.559 U/m L. There were significant different(Duncan, P 0.05) of the pectinase production with the agitation speed at static, 50, 100, 200 and 250 rpm. At the static condition, a well growth mycelial mat was observed on the surface of the cultivation medium and sporulation occurred all over the fungal mycelial mat. However with the increased in agitation speed, the mycelial mat turned slowly to become a single circular pellet. Thus, it was found that agitation speed affected the morphological characteristics of the fungal hyphae/mycelia of A. niger HFD5A-1 by altering their external as well as internal cell structures.CONCLUSION: Exposure to higher shear stress with an increasing agitation speed could result in lower biomass yields as well as pectinase production by A. niger HFD5A-1.     

Effect of COD/N ratio and salinity on the performance of sequencing batch reactors

The effects of COD/N ratio (3-6) and salt concentration (0.5-2%) on organics and nitrogen removal efficiencies in three bench top sequencing batch reactors (SBRs) with synthetic wastewater and one SBR with fish market wastewater were investigated under different operating schedules. The solids retention time (SRT, 20-100 days) and aeration time (4-10h) was also varied to monitor the performance. For synthetic wastewater, chemical oxygen demand (COD) removal efficiencies were consistently greater than 95%, irrespective of changes in COD/N ratio, aeration time and salt concentrations. Increasing the salt concentrations decreased the nitrification efficiency, while high COD/N ratio's favored better nitrogen removal (>90%). The treatment of real saline wastewater ( approximately 3.2%) from a fish market showed high COD (>80%) and nitrogen (>40%) removal efficiencies despite high loading rate and COD/N fluctuations, which is due to the acclimatization of the biomass within the SBR.     

Comparative study of olive oil mill wastewater treatment using free and immobilized Coriolopsis polyzona and Pycnoporus coccineus

The efficiency of the two white-rot fungi Pycnoporus coccineus and Coriolopsis polyzona in the Olive Oil Mill Wastewater (OOMW) treatment was investigated. Both fungi were active in the decolourisation and COD removal of OOMW at 50 g/L COD, but only the first fungus remains effective on the crude effluent (COD=100 g/L). Moreover P. coccineus was less affected by oxygen supplementation and exhibited a high tolerance to agitation in comparison to C. polyzona. However, it required a nitrogen supplementation to obtain faster and higher COD removal. To overcome the negative effect of agitation on fungi growth and efficiency, immobilisation of C. polyzona and P. coccineus in polyurethane foam was applied. The immobilized system showed better COD decreases during three consecutive batches without remarkable loss of performances. The results obtained in this study suggested that immobilized C. polyzona and especially immobilized P. coccineus might be applicable to a large scale for the removal colour and COD of OOMW.     

Effect of pH on the production of bacterial polyhydroxyalkanoates by mixed cultures enriched under periodic feeding

This research investigated the effect of pH on polyhydroxyalkanoate (PHA) production by mixed cultures enriched in a sequencing batch reactor (SBR) starting from activated sludge. The enrichment was performed with a mixture of acetic (85% on COD basis) and propionic (15%) acid, at an organic load rate of 8.5 gCOD/L/day over the range of pH from 7.5 to 9.5.The enriched cultures were all able to store the copolymer poly(3-hydroxybutyrate/3-hydroxyvalerate). Higher polymer production rates and yields (389 mg PHA (as COD)/g non-polymer biomass (as COD)/h and 0.53 COD/COD, respectively) were observed when the pH in the SBR was controlled at 7.5, with Lampropedia hyalina as the dominant bacterial species of the microbial community.PHA composition was also strongly affected by the pH. Indeed, batch tests showed that hydroxyvalerate (HV) content in the copolymer increased with increasing pH up to about 48% (mol/mol) at pH 9.5. Interestingly, the possibility of enhancing the HV content was also verified by performing batch tests at a more alkaline pH value than that in the SBR. In conclusion, this paper suggests that pH control is a main tool to tune HV content in the PHA, regardless of the feed composition.     

Impacts of cell surface characteristics on population dynamics in a sequencing batch yeast reactor treating vegetable oil-containing wastewater

Ten yeast strains acquired from different sources and capable of utilizing vegetable oil or related compounds (fatty acid or oleic acid) as sole carbon sources were inoculated into a sequencing batch reactor (SBR) for the treatment of high-strength vegetable oil-containing wastewater. The SBR system stably removed >89% of chemical oxygen demand (COD) and >99% of oil when fed with wastewater containing 15 g/L COD and 10 g/L oil in average. Denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 26S rRNA genes showed that among the ten yeast strains, only Candida lipolytica, Candida tropicalis, and Candida halophila were dominant in the system. To elucidate the major factors affecting the selection of yeast strains in the SBR system, the three dominant strains were compared with two non-dominant strains in terms of COD removal performance, biomass yield, cell settleability, cell flocculation ability, cell emulsification ability, and surface hydrophobicity. Results showed that hydrophobicity and emulsification ability of yeast cells were the two most important factors determining the selection of yeast strains in the treatment of high-strength oil-containing wastewater.     

Characterization of aerobic granules by microbial density at different COD loading rates

Aerobic granules were cultivated under temporal alternating aerobic and anoxic conditions without the presence of a carrier material in a sequencing batch reactor (SBR) with a high column height/column diameter ratio. The reactor was operated for 6h per cycle (aerobic: 4.75 h, anoxic: 1.25 h). To determine a new parameter for the definition of aerobic granules, a protocol of 4,6-diamidino-2-phenylindole hydrochloride staining and fluorescence image processing was developed. The d(tm) analysis showed that the increase in the chemical oxygen demand (COD) loading rate promoted no more growth of the aerobic granules. It was inconsistent with the results of the analysis of the sludge volume index (SVI) value but matched well with the results of the COD and nitrogen removal of the SBR and the particle size distribution by LS-PSA. The optimum COD loading rate for aerobic granulation in the SBR was 2.52 kg/m(3)d. When d(tm) was correlated with the biomass concentration and the SVI value during the period of granule formation, d(tm) could be used as a more sensitive and accurate parameter for classifying aerobic granules and optimizing the operational conditions for aerobic granulation processes.     

Effect of Extracellular Factors on Growth and Dimorphism of Rhizopus oryzae with Multiple Enzyme Synthesizing Ability

Rhizopus oryzae PR7 MTCC 9642 was a dimorphic fungus that showed a regular 90 days cycle of filament (mycelium) to pellet (yeast) transformation through a distinct bottom dwelling intermediate state and the pellets never revert back to filamentous form. Apart from the normal cycle, high temperature (37°C and above) and extreme pH also induced the yeast formation. Among the ions tested, calcium and chloride ions were found to restore the filamentous morphology, even in extreme pH and temperature. Cysteine HCl also played noteworthy role in maintaining mycelial growth even at adverse condition. Immobilized spores showed the appearance of intermediate form instead of typical yeast form even at high temperature. The strain could produce a number of extracellular hydrolytic enzymes like cellulolytic, xylanolytic, pectinolytic and amylolytic enzymes. The pellet and mycelial forms were found to be a better producer of cellulase–lignocellulase enzymes and amylolytic enzymes respectively, which might be correlated with their infectivity. Increase in inoculum size, agitation during cultivation, change in carbon and nitrogen source failed to induce mycelial growth in extreme conditions, which might be explained as irreversible change of configuration of protein responsible for mycelial development.     

Robustness of sludge enriched with short SBR cycles for biological nutrient removal

In this study, it is proposed that short sequencing batch reactor (SBR) cycles select and maintain a robust and active biomass, able to cope with typical disturbances occurring in wastewater treatment plants. In order to test this hypothesis, an SBR system was subjected to COD, N and P shock loads. It was shown that the sludge enriched in the SBR operated with short cycles was able to rapidly recover from the tested disturbances. COD and N removal recovered within 1–2 days for shock loads of 10 times the standard concentration. The P removal took up to 2–3 sludge ages to fully recover from the COD spike, but the enhanced biological phosphorus removal (EBPR) performance was still able to be totally re-established after each of the tests, even in theoretically adverse conditions for the growth of polyphosphate accumulating organisms.     

两种方法形成菌丝球固定2-氯酚降解菌的对比

【目的】系统研究吸附法和同时培养法对所形成混合菌丝球的外观形态、内部结构及其去除2-氯酚效果的影响。【方法】采用吸附法和同时培养法将可降解2-氯酚的光合细菌PSB-1D固定在黄孢原毛平革菌(Phanerochaete chrysosporium)DH-1发酵而成的菌丝球上,形成混合菌丝球。以单一菌丝球为对照,利用光学显微镜、扫描电镜等仪器观察混合菌丝球的外观形态和内部结构,考察2种方法对混合菌丝球成球效果的影响;以无菌培养液为空白对照,考察游离光合细菌、单一菌丝球、2种方法形成混合菌丝球对2-氯酚的降解效能。【结果】在吸附法形成的混合菌丝球上,光合细菌主要集中在过渡区;而同时培养法将光合细菌牢固地包埋在菌丝球内核区,并大量簇状附着生长在菌丝交联的空隙处和每根菌丝上。在接种等量孢子和光合细菌的前提下,同时培养法较吸附法操作时间更短,成球数量更多,形成菌丝球干湿比更大,单位菌丝干重上固定的细菌数量更多。菌丝球降解体系和游离光合细菌对2-氯酚的降解均符合一级动力学特征。同时培养法形成的混合菌丝球降解效果最好,7 d内对初始浓度为50 mg/L的2-氯酚降解率可达89%以上,降解速率常数为0.3286 mg/(L·d),2-氯酚半衰期t1/2为2.8 d。【结论】首次报道黄孢原毛平革菌包埋固定化光合细菌形成混合菌丝球。该研究为生物质固定化材料的实际应用提供理论依据。     

Use of Phanerochaete chrysosporium biomass for the removal of textile dyes from a synthetic effluent

Summary The use of Phanerochaete chrysosporium biomass for the removal of Reactofix Golden Yellow from aqueous solution and eight textile dyes (four azo and four anthraquinone) from a synthetic effluent (0.6 g/l) at different pH, temperature and biomass concentrations was studied. Adsorption was maximum at pH 2.0 and 40 °C using 2.45 g mycelial biomass. The rate constant of adsorption was 1.95×10⁻¹/min for Reactofix Golden Yellow and 1.64×10⁻¹/min for synthetic effluent. In both cases, the equilibrium data fitted well in the Langmuir but not the Freundlich model of adsorption, and the adsorption was biphasic. Adsorption decreased the COD of Reactofix Golden Yellow and synthetic effluent by 54 and 57%, respectively. Desorption (80–84%) of dyes from P. chrysosporium mycelial surface occurred as the pH increased from 2 to 10.