Enhanced biodegradation of 4-aminobenzenesulfonate in membrane bioreactor by Pannonibacter sp. W1

4-Aminobenzenesulfonate (4-ABS), an aromatic amine and recalcitrant toxic pollutant, is widely used in the dye and pharmaceutical industry. Pannonibactersp. W1 is a specialized microbial strain which can efficiently degrade 4-ABS. This study shows the feasibility of using the specialized strain in an MBR system to treat synthetic wastewater containing large amount of 4-ABS. Due to membrane retention, the biomass concentration is able to reach 5 g/L within two months of continuous operation. Pannonibacter sp. W1 is able to adapt to the high loading rate of 1000 mg 4-ABS/L and achieve a remarkable 4-ABS removal efficiency of 99% within 6 h. Strain W1 grows well under the MBR continuous operation and remains as the dominant bacterium at the end of 60 days continuous operation. Minor membrane fouling has been detected within 40 days of operating at 15 LMH. At a flux of 25 LMH, the system experiences the 'TMP jump'. The high organic removal rate and low membrane fouling results illustrate the excellent performance of the bioaugmented MBR system in 4-ABS wastewater treatment.     

Arsenic removal from groundwater by a newly developed adsorbent.

A novel adsorbent, which had been developed for phosphate adsorption, was adopted for arsenic removal from groundwater. Adsorption isotherm, pH dependence of the isotherm and adsorption rate were studied by batch method. Furthermore, by using a granular adsorbent of 1.8 mm diameter which is commercially available, lab-scale experiments of continuous adsorption treatment of actual groundwater containing arsenic at 50 mg m(-3) were conducted to examine the performance of the adsorbent. A large amount of arsenic, i.e., 10 g As kg(-1), was adsorbed at pH 7.0 and 10 mg As m(-3) in equilibrium concentration. It was only a 5% higher amount compared to conventional activated alumina. However, twice the bed volume, i.e., total volume of effluent divided by empty column volume, was achieved till breakthrough by using this novel adsorbent. This may be because the pH decrease, which enlarges apparent adsorption capacity of the adsorbent, is caused by a self-pH decrease function of the adsorbent. The self-pH decrease function must be delivered by dissociation of Al (III) aquoion. The proton release was clearly observed in batch experiments.     

Kinetics of growth and multi substrate degradation by an indigenous mixed microbial culture isolated from a wastewater treatment plant in Guwahati, India

An indigenous mixed culture of microorganisms, isolated from a sewage treatment plant, was investigated for its potential to simultaneously degrade phenol and m-cresol during its growth in batch shake flasks. 2(2) full factorial designs with the two substrates as the factors, at two different levels and two different initial concentration ranges, were employed to carry out the biodegradation experiments. For complete utilisation of phenol and m-cresol, the culture took a minimum duration of 21 hrs at their low concentration of 100 mg/L each, and a maximum duration of 187 hrs at high concentration of 600 mg/L each in the multisubstrate system. The biodegradation results also showed that the presence of phenol in low concentration range (100-300 mg/L did not inhibit m-cresol biodegradation; on the other hand, presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. During the culture growth, a lag phase was observed above a combined concentration of 500 mg/L i.e., 200 mg/L m-cresol and 300 mg/L of phenol and above). Statistical analysis of the specific growth rate of the culture in the multisubstrate system was also performed in the form of ANOVA and Student 't' test, which gave good interpretation in terms of main and interaction effects of the substrates.     

Effect of xylose and nutrients concentration on ethanol production by a newly isolated extreme thermophilic bacterium

An extreme thermophilic ethanol-producing strain was isolated from an ethanol high-yielding mixed culture, originally isolated from a hydrogen producing reactor operated at 70 degrees C. Ethanol yields were assessed with increasing concentrations of xylose, up to 20 g/l. The ability of the strain to grow without nutrient addition (yeast extract, peptone and vitamins) was also assessed. The maximum ethanol yield achieved was 1.28 mol ethanol/mol xylose consumed (77% of the theoretical yield), at 2 g/l of initial xylose concentration. The isolate was able to grow and produce ethanol as the main fermentation product under most of the conditions tested, including in media lacking vitamins, peptone and yeast extract. The results indicate that this new organism is a promising candidate for the development of a second generation bio-ethanol production process.     

Isolation of a phenol-utilizing marine bacterium from Durban Harbour (South Africa) and its preliminary characterization as Marinobacter sp. KM2

Many aromatic hydrocarbons assigned to the so-called high production volume chemicals (HPVCs) are frequently encountered constituents of wastewaters that end up in the sea. Although the pollutant-degrading capabilities of freshwater bacteria are well known, the catabolism of pollutants by marine bacteria has received limited attention. A marine bacterium with the ability to aerobically utilize phenol - an HPVC and common aromatic pollutant - as its sole source of carbon and energy, was isolated from water samples from Durban Harbour, South Africa. The isolate, designated strain KM2, was assigned to the genus Marinobacter based on a variety of phenotypic properties and by analysis of the 16S rRNA gene sequence. The isolate displays an absolute growth requirement for NaCl which cannot be offset by replacement of NaCl with other salts. In addition to 4-methylphenol and 3,4-dimethylphenol, it utilizes a range of aliphatic hydrocarbons such as butan-1-ol and hexadecane under aerobic conditions. The transient formation of an intermediate exhibiting the UV-Vis spectral characteristics for 2-hydroxymuconic semialdehyde in cultures growing on phenol suggests that the isolate catabolizes this compound via the meta cleavage pathway. These results indicate that members of the genus Marinobacter might participate in the elimination of aromatic pollutants in South African marine environments.     

Biosorption of Pb2+ and Cd2+ in a fixed bed column with immobilised Chorella sp. biomass

The biosorption of Pb2+ and Cd2+ in a fixed bed column by immobilised Chlorella sp. was characterised in a fixed bed column. Effect of initial concentration of Pb2+ and Cd2+, pH, and pellet size on the biosorption capacity was studied, at laboratory scale, using a factorial experiment design 2(3), in a 10 cm heightx1 cm of diameter continuous flow column packed with immobilised biomass. Equilibrium uptake of Pb2+ and Cd2+, increased with increasing initial metal ion concentration. It was favoured to pH 5, with a pellet of 5 mm of diameter. Langmuir model described the biosorption equilibrium of both metals.The biosorption of each single cation was studied too in a large column (50 cm heightx5 cm of diameter) at bench scale with a range of flow of 40 to 80 mL min(-1). The mass transfer coefficient was determined fitting the experimental data to continuity equations that were discretised in the radial terms with orthogonal collocation method.     

Biotreatment of paper mill effluent using alkaliphilic Rhizobium sp. NCIM 5590 isolated from meteoric alkaline Lonar Lake,Buldhana District,Maharashtra, India

Bacterial strain Rhizobium sp. was isolated from littoral soil of meteoric alkaline Lonar Lake and used to treat paper mill waste water. The bacterium was found to fix 125.7 nmol of C₂H₄ formed ml ^?1 culture media in 72 hr by ARA (acetylene reduction assay). The optimum pH for its growth was 12, whereas the optimum temperature was 40°C. The bacterium could tolerate salt concentrations up to 4%. The collected paper mill effluent used two dyes in combination, namely Acid Orange 7 (AO ) and Acid Yellow 17 (AY ) to produce brown paper, eventually producing coloured effluent containing unbound AO and AY . Rhizobium sp. was found to be efficient for decolorization of both AO and AY individually, as well as in a mixture of AO and AY , suggesting the ability of this strain for treating paper mill effluent. The strain was found to be efficient in reducing up to 85% of the colour from undiluted paper mill effluent within 18 hr. In addition, biotreatment also was effective in reducing COD , metals and toxicity from the waste water. Induction in the enzymes azo reductase and DCIP reductase indicated their possible involvement in biotreatment of paper mill effluent. The effluent toxicity before and after treatment was studied using Allium cepa root cells, evaluating various biochemical parameters to assess the toxicity, including lipid peroxidation, protein oxidation, antioxidant enzyme status (catalase, superoxide dismutase) and genotoxicity assays using single cell gel electrophoresis (SCGE ).     

Mechanism of adsorption of ferric iron by extracellular polymeric substances (EPS) from a bacterium Acidiphilium sp

The aim of this study was to assess the sorption of Fe(III) by extracellular polymeric substances (EPS) of the Acidiphilium 3.2Sup(5) bacterium, which has promising properties for use in microbial fuel cells (MFC). The EPS of A. 3.2Sup(5) was extracted using EDTA. The sorption isotherms were determined using aliquots of purified EPS. The exosubstances loaded with metal were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR). The sorption uptake approaches to 536.1 +/- 26.6 mg Fe(III) (g EPS)(-1) at an initial ferric concentration of 2.0 g l(-1). The sorption of Fe(III) by EPS can be fitted to the Freundlich model. The sorption process produces hydrated iron (III) oxalate [Fe(OH)(C2O4) x 2H2O] by a reversible reaction (log K = 1.06 +/- 0.16), indicating that a shift in the sorption of the cation can be easily achieved. Know the magnitude and form of iron sorption by EPS in MFC can foresee the potential impact on the metabolism of iron-reducing and iron-oxidazing bacteria and, therefore, on the feasibility of the system.     

Molecular typing of the Legionella pneumophila population isolated from several locations in a contaminated water network.

The RAPD (random amplified polymorphic DNA) technique has been developed for the molecular typing of Legionella in order to characterise the populations of hot water systems. During this study, 22 primers were tested and the four most informative ones were selected. The optimisation of the PCR conditions allowed the setting up of a powerful discriminative genotyping method. Moreover, the definition of a quality management method allowed definition of the key steps and the number of replicates to ensure reproducibility of the RAPD pattern. The RAPD was used to study the hot water network of a building. Legionella colonies (91) were isolated from seven locations and genotyped. The diversity of the population in one sample could vary from one to seven different strains. The study of the traceability showed that, in most of the cases, different populations could be present at different locations of the same network.     

Denitrification with epsilon-caprolactam by acclimated mixed culture and by pure culture of bacteria isolated from polyacrylonitrile fibre manufactured wastewater treatment system.

The aim of this study is to isolate denitrifying bacteria utilizing epsilon-caprolactam as the substrate, from a polyacrylonitrile fibre manufactured wastewater treatment system. The aim is also to compare the performance of PAN (polyacrylonitrile) mixed bacteria cultures acclimated to epsilon-caprolactam and isolated pure strain for treating different initial epsilon-caprolactam concentrations from synthetic wastewater under anoxic conditions. The result showed that the PAN mixed bacteria cultures acclimated to epsilon-caprolactam could utilize 1538.5 mg/l of epsilon-caprolactam as a substrate for denitrification. Sufficient time and about 2200 mg/l of nitrate were necessary for the complete epsilon-caprolactam removal. Paracoccus thiophilus was isolated from the polyacrylonitrile fibre manufactured wastewater treatment system and it could utilize 1722.5 mg/l of epsilon-caprolactam as a substrate for denitrification. About 3500 mg/l of nitrate was necessary for the complete removal of epsilon-caprolactam. When the initial epsilon-caprolactam concentration was below 784.3 mg/l, the removal efficiency of epsilon-caprolactam by Paracoccus thiophilus was better than that for the PAN mixed bacteria cultures. The growth of Paracoccus thiophilus was better. However, when the initial epsilon-caprolactam concentration was as high as 1445.8 mg/l, both the epsilon-caprolactam removal efficiency by Paracoccus thiophilus and Paracoccus thiophilus specific growth rate were similar to the PAN mixed bacteria cultures.     

Biosorption of lead(ll) and copper(ll) from stormwater by brown seaweed Sargassum sp.: batch and column studies.

This study evaluated the potential use of brown seaweed Sargassum sp to sequester lead and copper (Pb(II) and Cu(ll)) from urban runoff based on batch as well as column experiments. The equilibrium data exhibited Langmuir isotherms. The adsorption capacity of this seaweed was found to be 196.1 mgg(-1) and 84.0 mg g(-1) for Pb(ll) and Cu(ll), respectively, which are in good agreement with those values obtained for the aqueous solution (188.6 mg g(-1) for Pb(ll) and 86.9 mg g(-1) for Cu(II)). The functional group analysis of the seaweed using FTIR demonstrated that the carboxyl functional groups are mainly responsible for biosorption. The cation exchange capacity of the biosorbent was 2.25 meq/g. This observation suggested that ion exchange mechanism is predominantly responsible for the metal ion uptake. The column study showed that the highest bed height and the lowest flow rate result in a substantial enhancement of the metals uptake with the biosorption uptake capacities being 264.3 mg Pb(ll) g(-1) and 86.0 mg Cu(ll) g(-1). In the binary system, the biosorption capacity was observed to be 208.7 mg Pb(ll) g(-1) and 61.0 mg Cu(II) g(-1). The predicted breakthrough curves by the Thomas adsorption model gave a good fit of the experimental data with r2 ranging from 0.92 to 0.99.     

Removal of odorous sulphur-containing gases by a new isolate from activated sludge.

Biological treatment of odorous sulphur-containing compounds is attracting attention due to its benign eco-friendliness, energy-savings and low operating costs. As the biological treatment efficiency of dimethylsulphide (DMS) reported was often low and variable, selection of useful DMS-degrading microorganisms is of importance for the enhancement of the biological deodorizing process. This paper reports the successful isolation of a DMS-degrading bacterium from activated sludge, using the enrichment isolation technique. The isolate was identified by 16S rRNA gene sequencing, and found to belong to the alpha group of Proteobacteria, with an identity of 99.4% and 99.1% to the 16S rRNA gene sequences of Afipia felis and Pseudomonas carboxydohydrogena, respectively. The isolate was able to metabolize DMS as well as hydrogen sulphide (H2S). A batch experiment was performed to assess the removal characteristics of DMS by the isolate. The results showed that over half of DMS could be removed by the isolate in 3 hours when the initial DMS amount was approximately 10 micromol and 25 micromol. Removal of H2S by the isolate was evaluated by a continuous test in a 2-L gas-bubbling bottle. Although part of the H2S removal by the mineral medium itself was observed in the control test, the majority of H2S removal was believed to be attributed to the metabolic activity of the isolate. In conclusion, the isolate might be potentially useful for the enhancement of the biological deodorizing processes.     

Removal of detergents by activated petroleum coke from a clarified wastewater treated for reuse.

The removal of detergents from clarified wastewaters by activated petroleum coke (CAPA) was assessed. These substances, owing to their foamy properties, constitute a problem for ammonia removal by the air stripping process that could be installed in a wastewater treatment train to produce reclaimed water. CAPA was evaluated as a more economical alternative than a commercial activated carbon. Experimental work was divided in three stages: 1) production and characterisation of materials; 2) pretreatment of raw wastewater through the Fenton's reagent or coagulation-flocculation process with Al2(SO4)3; and 3) adsorption and bio-adsorption tests of clarified effluents. These tests were carried out in the laboratory in discontinuous and continuous reactors, the former by the "point-by-point" technique, with and without a previous fixing of bacteria, and the latter by the Rapid Small Scale Column Test. Detergents content, color, COD and UV254nm were measured in raw and treated wastewaters. Results show that the best pretreatment for the adsorption process was coagulation-flocculation rather than Fenton's method. Oxidation by this process decreased the adsorptive properties of detergents. Biomass fixed on the CAPA particles significantly increased the UV254nm and COD removal efficiencies (20% and 170% respectively). The breakthrough curves showed that CAPA could attain the expected detergents removal efficiency (66%) for the alum effluent.     

Evaluation of virological quality of sewage from four biological treatment plants by a nested-PCR technique.

In order to determine the virological quality of sewage from four biological treatment plants in Greece (two in the city of Athens and two in the city of Patras), 92 raw sewage samples were analysed for the presence of enteroviruses and adenoviruses during the period from October 2000 to February 2003. A nested-PCR method was used in order to increase the sensitivity of virus detection. Enteroviruses were detected in 43 samples (47%) and adenoviruses in 75 samples (81.5%) of raw sewage by nested PCR. The more frequent isolation of adenoviruses in raw sewage indicated their stability as virological indicators of the pollution of the environment and their increased persistence in sewage.     

Influence of CO2 scrubbing from biogas on the treatment performance of a high rate algal pond.

Biogas produced by anaerobic treatment of wastewater can be collected and used for power generation. However, the biogas may require scrubbing to prevent corrosion by H2S and to improve engine efficiency by reducing the CO2 content. HRAP can be used to scrub biogas during the daytime when they are carbon-limited and have high pH. This study investigates the influence of the carbon dioxide addition from biogas scrubbing on high rate algal pond wastewater treatment performance (in terms of BOD, NH4-N, DRP and E. coli removal) and algal production (growth and species composition). Batch culture experiments were conducted in laboratory microcosms (2 L) and outside mesocosms (20 L). Results indicate that CO2 addition and reduced culture pH increased algal production and nutrient assimilation, decreased high pH mediated nutrient removal processes (phosphate precipitation and ammonia volatilisation), but had little influence on the ability of the culture to remove filtered BODs. Disinfection, as indicated by E.coli removal; was reduced, however, further research on virus removal, which is not affected by culture pH, is required. These preliminary findings indicate the potential to scrub C02 from biogas using high rate pond water without decreasing the effectiveness of wastewater treatment and enabling increased recovery of wastewater nutrients as algal biomass.     

Development of a process for the recovery of phosphorus resource from digested sludge by crystallization technology.

Removal and recovery of phosphorus from sewage in form of MAP (magnesium ammonium phosphate) have attracted attention from the viewpoint of eutrophication prevention and phosphorus resource recovery as well as scaling prevention inside digestion tanks. In this work, phosphorus recovery demonstration tests were conducted in a 50 m3/d facility having a complete mixing type reactor and a liquid cyclone. Digested sludge, having 690 mg/L T-P and 268 mg/L PO4-P, was used as test material. The T-P and PO4-P of treated sludge were 464 mg/L and 20 mg/L achieving a T-P recovery efficiency of 33% and a PO4-P crystallization ratio of 93%. The reacted phosphorus did not become fine crystals and the recovered MAP particles were found to be valuable as a fertilizer. A case study in applying this phosphorus recovery process for treatment of sludge from an anaerobic-aerobic process of a 21,000 m3/d sewage system, showed that 30% of phosphorus concentration can be reduced in the final effluent, recovering 315 kg/d as MAP.     

Removal of C.I. Reactive Red 2 from aqueous solutions by chitin: an insight into kinetics, equilibrium, and thermodynamics

In this study, C.I. Reactive Red 2 (RR2) was removed from aqueous solutions by chitin. Exactly how the RR2 concentration, chitin dosage, pH, and temperature affected adsorption of RR2 by chitin was then determined. After reaction for 120 min, the amount of 10 and 20 mg/L RR2 absorbed onto chitin was 5.7 and 7.5 mg/g, respectively. The adsorption percentage increased from 56 to 94% when the chitin dosage was increased from 1.5 to 2.5 g/L. Experimental results indicated that the pseudo-second-order model best represents adsorption kinetics. Adsorption of RR2 increased as the temperature increased; however, it decreased with an increased pH. Experimental results further demonstrated that the Freundlich model is superior to the Langmuir model in fitting experimental isotherms. The ΔH° and ΔS° were 16.34 kJ/mol and 152.10 J/mol K, respectively. ΔH° suggested that adsorption of RR2 onto chitin was via physisorption.     

Photocatalytic inactivation of Flavobacterium and E. coli in water by a continuous stirred tank reactor (CSTR) fed with suspended/immobilised TiO2 medium

A photocatalytic continuous stirred tank reactor (CSTR) was built at laboratory scale to inactivate two environmental bacteria strains (Flavobacterium and E. coli) in tap water. Several parameters were found to impact reactor efficiency. Bacterial initial concentration is an important factor in inactivation rate. After 30 minutes of irradiation at 10(8)-10(9) CFU mL(-1) starting concentration, a >5 log reduction was achieved while at 10(4)-10(6) CFU mL(-1) only a 2 log reduction was observed. Water hardness and pH have an important influence on the photocatalytic inactivation process. Soft water, with low Ca(+2) and Mg(+2) at low pH approximately 5.3 resulted in increased inactivation of Flavobacterium reaching >6 orders of magnitude reduction. E. coli and Flavobacterium at pH 5 were inactivated by 3 logs more as compared to pH 7 under similar conditions. pH below TiO2 isoelectric point (approximately 5.6) supports better contact between bacteria and anatase particles resulting in superior inactivation. TiO2 powder suspension was compared with immobilised powder in sol-gel coated glass beads in order to exclude the need for particles separation from the treated water. TiO2 suspension was more effective by 3 orders of magnitude when compared to coated glass beads. An interesting observation was found between the two bacterial strains based on their hydrophobicity/hydrophilicity balance. The more hydrophobic Flavobacterium compared to E. coli was inactivated photocatalytically by >3 logs more then E. coli in the first 30 minutes of irradiation interval. The results indicate the importance of the parameters involved in the contact between TiO2 particles and microorganisms that govern the successful inactivation rate in CSTR.