Boron bioremoval by a newly isolated Chlorella sp. and its stimulation by growth stimulators

It has been well documented that excess concentrations of boron (B) causes toxic effects on many of the environmental systems. Although Chlorella sp. has been studied to remove pollutants from water, its capacity to remove B has not been investigated yet. Boron removal levels of newly isolated Chlorella sp. were investigated in BG 11 media with stimulators as triacontanol (TRIA) and/or sodium bicarbonate (NaHCO₃) and without them, to test if they could increase the removal efficiency by increasing biomass. The assays were performed to determine the effect of different medial compositions, B concentrations, pH and biomass concentrations onto removal efficiency. Boron removal was investigated at 5-10 mg/L range at pH 8 in different medial compositions and maximum removal yield was found as 32.95% at 5.45 mg/L B in media with TRIA and NaHCO₃. The effect of different pH values on the maximum removal yield was investigated at pH 5-9, and the optimum pH was found again 8. The interactive effect of biomass concentration and B removal yield was also investigated at 0.386-1.061 g wet weight/L biomass. The highest removal yield was found as 38.03% at the highest biomass range. This study highlights the importance of using new isolate Chlorella sp. as a new biomaterial for B removal process of waters containing B.     

Removal of phenolic compounds from raw industrial wastewater by Achromobacter sp. isolated from a hydrocarbon‐contaminated area

The discharge of raw industrial wastewaters, specifically coking wastewater, represents a severe environmental problem. In this work, a phenol‐degrading aerobic strain isolated from a hydrocarbon contaminated site, Achromobacter sp. C‐1, was tested for degrading raw coking wastewater to explore its potential for use in biological treatment. Initially, phenol degradation was reached after 24 h of inoculation in synthetic wastewater [600 mg/L of phenol]. The maximum specific degradation rate was 0.436 h^–1 found in the concentration 300 mg/L. In a raw industrial wastewater containing a mixture of phenols as carbon source [phenol 370 mg/L, m‐cresol 100 mg/L and o‐cresol 60 mg/L], 90% biodegradation of a mixture of phenols was achieved after 80 h of inoculation. Following the biodegradation process to remove the colour from the wastewater, polishing was performed by activated carbon adsorption, resulting in a clear wastewater (without colour and contaminants) ready for industrial reuse purposes. These results provided useful information about use of the phenol‐degrading bacteria for bioaugmentation in industrial wastewater treatment improving the quality of final wastewater. The quality of the resulting wastewater was confirmed by mass spectrometry analysis. This work shows the biodegradation process could be a cost‐effective and promising solution for the treatment and reuse of phenolic wastewater.      

Biodegradation of pyridine using aerobic granules in the presence of phenol

Aerobic granules cultivated with 500mg/L phenol medium effectively degraded pyridine at a concentration of 250-2500mg/L; maximum degradation rate was 73.0mg pyridineg/VSS/h at 250mg/L pyridine concentration. Phenol concentrations of 500-2000mg/L limited pyridine degradation in a competitive inhibition pattern, as interpreted using Michaelis-Menten kinetics with corresponding parameters V(max), K(m) and K(I) of 63.7mg/Lh(-1), 827.8 and 1388.9mg/L, respectively. Fluorescent staining and confocal laser scanning microscopy (CLSM) tests suggested that an active biomass accumulated at the granule outer layer. Denaturing gradient gel electrophoresis (DGGE) fingerprint profile demonstrated that dominating microbial strains exist in phenol and pyridine-degrading aerobic granules.     

Kinetics of phenol biodegradation in high salt solutions

Biological treatment of high-salinity industrial wastewaters using halophilic bacteria can be used to remove organic compounds without first decreasing the salt concentration. While halophilic degradation of phenol and other organics has been investigated, there exists a general absence of kinetic data in current literature to allow evaluation of this treatment alternative. Liquid, soil and sediment samples were collected from three distinct saline environments in the western United States. Samples were enriched in media containing 10% (w/v) NaCl at pH 7.0, with phenol as a substrate. Mixed culture batch experiments were conducted at 30 degrees C with initial phenol concentrations of 50 mg/L. Evaluation of phenol degradation and corresponding cell growth data with Monod and Andrews models indicated that the kinetics were zero-order with respect to phenol. Zero-order specific growth rates ranged from 0.22 to 0.32 h(-1), while observed cell yields were 0.18-0.28 mg cell protein/mg phenol for the five cultures. For one of the cultures, phenol degradation rates were also quantified at concentrations of up to 320 mg/L. Under these conditions, specific growth rates ranged from 0.09 to 0.22 h(-1), decreasing with increasing initial phenol concentrations. Cell yields at these higher initial phenol concentrations ranged from 0.20 to 0.29 mg cell protein/mg phenol.     

Optimization of phenol removal from wastewater by activation of persulfate and ultrasonic waves in the presence of biochar catalyst modified by lanthanum chloride

In this paper, the effects of phenol concentration, pH, catalyst dose, persulfate concentration, temperature and contact time on the phenol removal from wastewater by activation of persulfate (S₂O₈^?2) in the presence of biochar modified by lanthanum chloride and ultrasonic waves (US) are optimized. Experimental design and optimization were carried out by response surface methodology. The optimum conditions for the maximum phenol removal were obtained pH of 4, phenol concentration of 86 mg/L, catalyst dose of 43 mg/L, persulfate concentration of 86 mg/L, temperature of 41 °C and contact time of 63 min. The optimum phenol removal from synthetic wastewater was attained 97.68%. Phenol removal by the mentioned system was fitted with the first‐order kinetic model. The combination of the ingredients of ‘S₂O₈^?2/US/Biochar‐LaCl₃’ system had a synergistic effect on the phenol removal.     

A study of external mass transfer effect on biodegradation of phenol using low‐density polyethylene immobilized Bacillus flexus GS1 IIT (BHU) in a packed bed bioreactor

The impact of external mass transport on the biodegradation rate of phenol in a packed bed bioreactor (PBBR) was studied. A potential bacterial species, Bacillus flexus GS1 IIT (BHU), was isolated from the petroleum‐contaminated soil. Low‐density polyethylene (LDPE) immobilized with the B. flexus GS1 IIT (BHU) was used as packing material in the PBBR. The PBBR was operated by varying the inlet feed flow rate from 4 to 10 mL/min, and the corresponding degradation rate coefficients were found to be in the range of 0.119–0.157 L/g h. In addition, the highest removal rate of phenol was obtained to be 1.305 mg/g h at an inlet feed rate of 10 mL/min. The external mass transfer was studied using the model . A new empirical correlation for the biodegradation of phenol in the PBBR was developed after the evaluation at various values of K and n.     

Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm

In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent.In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10⁻⁹ mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10⁻¹¹-2.04 × 10⁻¹⁰ and 8.04 × 10⁻¹¹-4.39 × 10⁻¹⁰ (mg phenol/CFU/h), respectively.In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ_max = 1.15/h, K_s = 35.4 mg/L and K_i = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes.Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass.Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed.     

Performance comparison of constructed wetlands with gravel- and rice husk-based media for phenol and nitrogen removal

This study aims to compare the performance of planted and unplanted constructed wetlands with gravel- and raw rice husk-based media for phenol and nitrogen removal. Four laboratory-scale horizontal subsurface-flow constructed wetland units, two of which planted with cattail (Typha latifolia) were operated outdoors. The units were operated at a nominal hydraulic retention time of 7 days and fed with domestic wastewater spiked with phenol concentration at 300 mg/L for 74 days and then at 500 mg/L for 198 days. The results show that planted wetland units performed better than the unplanted ones in the removal and mineralization of phenol. This was explained by the creation of more micro-aerobic zones in the root zone of the wetland plants which allow a faster rate of phenol biodegradation, and the phenol uptake by plants. The better performance of the rice husk-based planted wetland compared to that of the gravel-based planted wetland in phenol removal could be explained by the observation that more rhizomes were established in the rice husk-based wetland unit thus creating more micro-aerobic zones for phenol degradation. The role of rice husk as an adsorbent in phenol removal was considered not of importance.     

Isolation,characterisation and efficacy of the bacterial strain Lysinibacillus sphaericus YMM in biodegradation of malathion insecticide in liquid media

A new isolate of bacterium Lysinibacillus sphaericus YMM capable of degrading malathion insecticide in liquid media was isolated and characterised. Biodegradation factors were investigated using Plackett–Burman factorial design, and the rest of the insecticide was monitored by high-performance liquid chromatography analysis. The near optimum conditions for degradation of 200 mg malathion/L were 30 mL medium, 2% of L. sphaericus suspension (0.70 OD_600nm), pH 5,10 g/L glucose, 1.0 g/L NaCl, 0.3 g/L MgSO₄, 1.0 g/L NH₄Cl and incubation for 24 h without yeast extract and peptone or beef extract. In addition, the significant variables including the medium volume, inoculum and incubation time were further optimised using Box–Behnken response surface design. These conditions were found to be 30.10% medium and inoculum of 0.706 (OD_600nm) for 23.636 h of incubation to achieve 98.974% degradation. Therefore, L. sphaericus YMM showed a potential degradation of malathion. Further studies should be conducted to understand the mechanism of biodegradation in liquid media.     

Phenol biodegradation and its effect on the nitrification process

Phenol biodegradation under aerobic conditions and its effect on the nitrification process were studied, first in batch assays and then in an activated sludge reactor. In batch assays, phenol was completely biodegraded at concentrations ranging from 100 to 2500 mg l(-1). Phenol was inhibitory to the nitrification process, showing more inhibition at higher initial phenol concentrations. At initial phenol concentrations above 1000 mg l(-1), the level of nitrification decreased. In the activated sludge reactor, the applied ammonium loading rate was maintained at 140 mg N-NH(4)(+)l(-1)d(-1) (350 mg N-NH(4)(+)l(-1)) during the operation time. However, the applied organic loading rate was increased stepwise from 30 to 2700 mg COD l(-1)d(-1) by increasing the phenol concentration from 35 up to 2800 mg l(-1). High phenol removal efficiencies, above 99.9%, were maintained at all the applied organic loading rates. Ammonium removal was also very high during the operation period, around 99.8%, indicating that there was no inhibition of nitrification by phenol.     

Repeated phosphate removal from recirculating aquaculture system using cyanobacterium remediation and chitosan flocculation

Unicellular cyanobacterium Synechocystis sp. was used for phosphate removal in a recirculating aquaculture system. The cell harvesting was performed using chitosan solution in this study. The parameters (i.e. cell density, pH of cell suspension and chitosan concentration) affecting the flocculation efficiency of chitosan were investigated. With the optimal condition, the repeated flocculation for phosphate removal in a photobioreactor was demonstrated. The results show that the flocculation efficiency of chitosan depends on cell density, pH of cell suspension and chitosan concentration. The optimal flocculation process could be accomplished by adjusting the pH to 7.2 before adding 20 mg/L chitosan followed by pH adjustment to 7.5. With single inoculation, the sequential process of phosphate removal using cyanobacterial uptake followed by cell flocculation using chitosan with the optimal condition in the photobioreactor was successfully achieved for 12 cycles with water from a recirculating fish tank.     

Biodegradation of chlorpyrifos and 3, 5, 6‐trichloro‐2‐pyridinol by a novel rhizobial strain Mesorhizobium sp. HN3

A chlorpyrifos (CP) and 3,5,6‐trichloro‐2‐pyridinol (TCP) degrading bacterial strain, Mesorhizobium sp. HN3, was isolated and characterized. Mesorhizobium sp. HN3 degraded CP efficiently up to 400 mg/L initial concentration at wide range of temperatures (30–40°C) and pH (6.0–8.0). However, optimal degradation of CP was achieved at 37°C and neutral pH (7.0) at an initial inoculum density 2 × 10⁷ colony forming unit/mL of culture medium. Kinetic parameters for CP degradation by Mesorhizobium sp. HN3 were estimated at different initial concentrations. Cultures exhibited significant variation (P ≤ 0.05) in the specific growth rate (μ), cell mass formation rate (Q_X) and the substrate uptake rate (Q_S) during degradation of CP. The values of kinetic parameters increased up to 100 mg/L CP and decreased at higher concentration. Investigation of degradation metabolites indicated that CP is converted to diethylthiophosphate and TCP that leads to the formation of 3,5,6‐trichloro‐2‐methoxypyridine.     

Treatment of phenol and cresols in upflow anaerobic sludge blanket (UASB) process: a review

Upflow anaerobic sludge blanket (UASB) process has been successfully applied in the treatment of municipal and industrial wastewaters. Several researchers have investigated the suitability of the process for the treatment of phenols and phenolic wastewaters. The anaerobic treatment of phenols is still at an investigative stage. With increasing recognition of the UASB process, feasibility studies on the treatment of wastewater containing phenol and cresols (o-, m- and p- isomers) in UASB have been reviewed. It is reported that phenol concentration up to a range of 500-750 mg/L is generally not inhibitory to the UASB process. Phenol concentrations greater than 500 mg/L can be effectively treated with acclimatization of inocula, recirculation of the treated effluent and/or supplementing with co-substrates such as glucose, VFA and dilute molasses. The degradability of phenol is more than p-cresol, which in turn is more than m- and o-cresol.     

二氧化钛膜光催化氧化苯酚的动力学规律

采用主波长为２５３７ｎｍ的紫外光杀菌灯或主波长为３６５ｎｍ的黑光灯作为光源,研究了二氧化钛（ＴｉＯ２）膜光催化氧化苯酚水溶液的动力学规律。结果表明：ＴｉＯ２膜光催化氧化苯酚水溶液的动力学可以用ＬａｎｇｍｕｉｒＨｉｎｓｈｅｌｗｏｏｄ（Ｌ－Ｈ）动力学方程描述,但Ｌ－Ｈ方程只是表面反应的必要条件,并不充分;苯酚水溶液在黑光灯／ＴｉＯ２膜处理方式下的降解规律与Ｌ－Ｈ方程揭示的动力学变化过程相吻合;在起始浓度范围相同（２４～１６９０ｍｇ／Ｌ）的情况下,杀菌灯光催化氧化苯酚水溶液表现为一级反应动力学规律;不管哪种光源,ＴｉＯ２膜光催化矿化起始浓度７４０ｍｇ／Ｌ苯酚水溶液的过程均服从一级反应动力学。     

Effect of backwashing on perchlorate removal in fixed bed biofilm reactors

The influence of backwashing on biological perchlorate reduction was evaluated in two laboratory scale fixed bed biofilm reactors using 1- or 3-mm glass beads as support media. Influent perchlorate concentrations were 50 microg/L and acetate was added as the electron donor at a concentration of 2 mg C/L. Perchlorate removal was evaluated at various influent dissolved oxygen (DO) concentrations. Complete perchlorate removal was achieved with an influent DO concentration of 1mg/L resulting in bulk phase DO concentrations below the detection limit of 0.01 mg/L. The influence of increasing influent DO concentrations for 12 h periods was evaluated before and after individual backwash events. Partial perchlorate removal was achieved with an influent DO concentration of 3.5 mg/L before a strong backwash (bulk phase DO concentrations of approximately 0.2mg/L), while no perchlorate removal was observed after the strong backwash at the same influent DO level (bulk phase DO concentrations of approximately 0.8 mg/L). The immediate effect of backwashing depended on influent DO concentrations. With influent DO concentrations of 1 mg/L, strong backwashing resulted in a brief (<12 h) increase of effluent perchlorate concentrations up to 20 microg/L; more pronounced effects were observed with influent DO concentrations of 3mg/L. Daily weak backwashing had a small and, over time, decreasing negative influence on perchlorate reduction, while daily strong backwashing ultimately resulted in the breakdown of perchlorate removal with influent DO concentrations of 3 mg/L.     

Use of starch and potato peel waste for perchlorate bioreduction in water

The cost of carbon substrates for microbial reduction of perchlorate (ClO(4)(-)) is central to the success and competitiveness of a sustainable bioremediation strategy for ClO(4)(-). This study explored the potential application of starch in combination with an amylolytic bacterial consortia and potato peel waste for ClO(4)(-) bioreduction. We obtained a potent amylolytic bacterial consortium that consisted of a Citrobacter sp. S4, Streptomyces sp. S2, Flavobacterium sp. S6, Pseudoxanthomonas sp. S5, Streptomyces sp. S7, and an Aeromonas sp. S8 identified by 16S rDNA sequencing. ClO(4)(-) concentration substantially decreased in purified starch medium inoculated with the amylolytic bacterial consortium and Dechlorosoma sp. perclace. Potato peel waste supported ClO(4)(-) reduction by perclace with the rate of ClO(4)(-) reduction being dependent on the amount of potato peels. Over 90% ClO(4)(-) removal was achieved in 4 days in a single time point experiment with 2% (w/v) potato peels waste. ClO(4)(-) reduction in a non-sterile 0.5% potato peel media inoculated with perclace occurred with an initial concentration of 10.14+/-0.04 mg L(-1) to 2.87+/-0.4 mg L(-1) (71.7% reduction) within 5 days. ClO(4)(-) was not detected in the cultures in 6 days. In a non-sterile 0.5% potato media without perclace, ClO(4)(-) depletion occurred slowly from an initial value of 9.99+/-0.15 mg L(-1) to 6.33+/-0.43 mg L(-1) (36.63% reduction) in 5 days. Thereafter, ClO(4)(-) was rapidly degraded achieving 77.1% reduction in 7 days and not detected in 9 days. No susbstantial reduction of ClO(4)(-) was observed in the sterile potato peel media without perclace in 7 days. Redox potential of the potato peel cultures was favorable for ClO(4)(-) reduction, decreasing to as low as -294 mV in 24 h. Sugar levels remained very low in cultures effectively reducing ClO(4)(-) and was substantially higher in sterilized controls. Our results indicate that potato peel waste in combination with amylolytic microorganisms and Dechlorosoma sp. perclace can be economically used to achieve complete ClO(4)(-) removal from water.     

厌氧/好氧/生物脱氨工艺处理煤化工废水

采用厌氧/好氧/生物脱氨/混凝沉淀工艺处理煤化工废水,设计总处理量为360m3/h。4个多月的调试运行结果表明,该工艺运行稳定,耐冲击负荷能力强,当进水平均COD为2 141 mg/L、总酚为391 mg/L、氨氮为92 mg/L时,处理后出水COD100 mg/L、总酚10 mg/L、氨氮15 mg/L,出水水质达到《污水综合排放标准》(GB 8978—1996)的一级标准。     

Treatment of wastewater containing high concentrations of terephthalic acid by Comamonas sp. and Rhodococcus sp.: kinetic and stoichiometric characterization

In this work, terephthalic acid degradation was studied with two strains that were isolated and identified as closely related to Comamonas (99%) and Rhodococcus (99%) genus. A characterization of both strains was carried out during batch experiments performed at two oxygen transfer capacities (0.094 ± 0.011 and 0.538 ± 0.042 g O₂/L/h) and five concentrations of terephthalic acid (2.5 to 15.0 g/L). Maximum degradation rates of 0.073 ± 0.004 and 0.062 ± 0.003 g TOC/L/h, were observed, for Comamonas sp. and Rhodococcus sp., respectively. However, a degradation rate of 0.159 ± 0.011 g TOC/L/h was reached with a mixed culture. Haldane, Aiba, Edwards and Andrews models were used to fit terephthalic acid degradation kinetics, being Haldane the model that best fitted the results. Several parameters were determined including, maximum growth rate, growth yield, substrate affinity and inhibition constant.     

O3／BAC工艺中溴酸盐的控制

通过试验考察了活性炭、陶粒以及挂膜陶粒对溴酸盐的去除效果,分析了微生物对溴酸盐的降解作用。结果表明,在滤池以及生物活性炭滤池内成熟的微生物膜对溴酸盐有降解能力,溴酸盐去除量与水力接触时间的关系为9．16μg（L·h）。在活性炭（GAC）吸附以及微生物降解协同作用下,可以在不增加运行成本的基础上稳定、有效地控制溴酸盐。     

Enhanced electrocoagulation–electroflotation for turbidity removal by Opuntia ficus indica cladode mucilage

The optimisation of the electrocoagulation‐electroflotation (EC‐EF) process assisted by the mucilage of the Opuntia ficus indica (OFI), on the turbidity removal was performed through the response surface methodology (RSM). For a solution of 300 mg/L of silica gel, high turbidity removal (93.14% ± 1.31) was obtained under the optimal conditions of 2.5 mg/L, 21.2 V, 9.65 and 2.61 mS/cm for the mucilage concentration, voltage, pH and conductivity, respectively, this experimental value was close to the predicted value of 92.96% ± 0.3. OFI mucilage increases turbidity removal efficiency and reduces specific energy consumption at a fixed current density. The turbidity removal of the EC‐EF process was improved by 30.94% compared with the conventional EC–EF (EC–EF without OFI mucilage) which shows 62.02% ± 1.45 of turbidity removal.