High nitrate removal from synthetic wastewater with the mixed bacterial culture

The applicability of the mixed bacterial culture, originated from two-stage anaerobic-aerobic industrial yeasts production wastewater treatment plant for high rate denitrification processes was investigated. After acclimation to nitrate, the dominant strains were Pseudomonas and Paracoccus sp. Complete denitrification with low accumulation of nitrite-N (0.1 mg/l) was found in synthetic wastewater, obeying a zero-order reaction with respect to nitrate and a first-order reaction with respect to biomass concentration. Denitrification was then monitored in the continuous-flow stirred reactor at different hydraulic retention time, HRT (62-28 h) in order to achieve the optimal HRT. Nitrate was completely removed during following 45 days, at 25 degrees C with HRT, which we reduced from 62 to 28 h. Yet still, at 28 h HRT, high average specific denitrification rate of 142 mg NO3- -N/g VSS h was obtained.     

污水和污泥中的人工合成麝香分析方法

市政污水和污泥排放是人工合成麝香输入土壤环境的主要途径,污染物排放是生态风险评价中暴露分析模型的必要输入参数。目前有关土壤中人工合成麝香的生态风险研究较少报道,其中缺乏快捷、简便、准确的检测技术是限制这方面研究的主要因素之一。本研究针对污水的固相萃取法和液-液萃取法,以及脱水污泥的索氏萃取法和快速溶剂萃取(ASE)法进行比较和优化,结果表明,采用液-液萃取法和ASE法结合硅胶小柱净化过程检测水样和污泥样品中的人工合成麝香能够获得较好的回收率。最后利用这2种方法检测了北京某污水处理厂的进出水和脱水污泥中的佳乐麝香(HHCB)和吐纳麝香(AHTN)的含量,结果表明,进水中的HHCB和AHTN的含量分别为897～1270ng·L-1和331～488ng·L-1,出水中含量分别为201～226ng·L-1和65～130ng·L-1,脱水污泥中的含量分别为137～348ng.g-1和64～138ng.g-1。     

Biotreatment of p-nitrophenol and nitrobenzene in mixed wastewater through selective bioaugmentation

This work combined selective adsorption and bioaugmentation to treat mixed wastewater of nitrobenzene and p-nitrophenol. The mixed wastewater of nitrobenzene (217 mg/L) and p-nitrophenol (500 mg/L) was adjusted its pH to 8 and then passed through the adsorption column at 100 mL/h. In effluent the nitrobenzene concentration was less than 4 mg/L. Without the toxic inhibition of nitrobenzene, p-nitrophenol in effluent could be degraded within 60 h through bioaugmentation. About 23 mg/g of nitrobenzene adsorbed the dry resin HU-05 could be desorbed and degraded through bioaugmentation. During this process the adsorption capacity of the resin HU-05 was recovered partly. The recovered extent was limited by nitrobenzene bioavailability. The performance of the resin HU-05 kept stably in the recycle experiments of 60 days.     

Biodegradation kinetics of stored wastewater substrates by a mixed microbial culture

The anaerobic accumulation of several organic pollutants from industrial wastewaters, as storage substrates, and their subsequent aerobic biodegradation using a wastewater treatment mixed microbial culture for biological nutrient removal has been studied. The amount and the kinetics of substrate accumulation in the anaerobic stage depended on the characteristics of the wastewater fed to the anaerobic stage. Depending on the substrate used, levels of between 27 and 86% of storage polymers were accumulated with respect to the level obtained on feeding with acetate. The biodegradation kinetics were studied by modelling respirometry results. During the aerobic stage, oxygen-consumption data obtained in the respirometric tests were fitted to a model using a non-linear fitting estimation method. The simulation data obtained correlated well with the experimental oxygen-consumption data. The estimated kinetic parameters obtained indicate that each storage polymer was degraded at a different rate. However, the values obtained for the storage polymer half-saturation coefficient, K_S: 16 mg COD l⁻¹, and for the coefficient for endogenous respiration, b: 0.008 h⁻¹, were similar in all the experiments. The results indicate that each substrate produces the synthesis of a specific storage polymer that is degraded at a different rate.     

Application of a bioluminescence ATP assay in brewery wastewater treatment studies

The importance of having a rapid method for determining the viable biomass in activated-sludge wastewater treatment plants (WWTP) for process control and development is well recognized. The firefly bioluminescence ATP assay has been proposed for this purpose. Such an assay using partially purified firefly luciferase and synthetic firefly luciferin for the bioluminescence reaction, a liquid scintillation counter in the out-of-coincidence mode as luminescence detector, and a sludge ATP extraction technique involving dimethyl sulfoxide at room temperature is described. Experiments with several pure bacteria cultures were done to demonstrate the feasibility of applying this assay to activated sludge to activated sludge WWTP investigation and control. The ATP content of samples taken from various points in a 350000 gal/day brewery activated-sludge WWTP was monitored for 4.5 months. Good linear correlation between ATP and mixed-liquor suspended solids, return sludge suspended solids, and effluent suspended solids were observed. Percentage viabilities of the various sludge samples were derived from the ATP results.     

Nitrogen removal from synthetic wastewater using single and mixed culture systems of denitrifying fungi,bacteria, and actinobacteria

Applied Microbiology and Biotechnology - The aim of this study was to investigate the effects of single and mixed culture of denitrifying fungi, bacteria, and actinobacteria on nitrogen removal and...     

Estimation of dominant microbial population sizes in the anaerobic granular sludge of a full-scale UASB treating streptomycin wastewater by PCR-DGGE

Although the dominant members of microbial communities in wastewater bio-treatment systems were often paid attention due to their possible important roles in treatment performance, their population sizes, especially the unculturable species, were still little known. Then PCR-DGGE was used in an attempt to estimate the dominant microbial population sizes in the anaerobic granular sludge treating streptomycin wastewater, coupled with an inoculated strain (Esherichia coli) with known population sizes as an internal standard. The results indicated that the band intensities of the inoculated strain in DGGE profiles showed good correlation with population sizes. Then it was possible to estimate the dominant microbial population sizes by means of comparing their DGGE band intensities with the inoculated strain. The estimated results demonstrated that the sizes of major dominant microbial populations in the sludge sample were at the level of 10⁷–10⁸ CFU/g. The sizes of secondary dominant microbial populations were at the level of 10⁵–10⁶ CFU/g. The microbial populations with the size level lower than 10³ CFU/g were undetectable by PCR-DGGE. These results provided a potential approach to evaluate dominant microbial population sizes in complex microbial communities.     

Comparison of methods for monitoring bacterial transport in the subsurface

The purpose of this study was to compare in a laboratory experiment, a suite of methods developed to track viable bacteria during field transport experiments. The criteria for development and selection of these methods included: (1) the ability to track bacteria within the environment from which they were isolated; (2) the lack of any effect upon the viability or the transport characteristics of the strain; (3) low detection limits; (4) a quantification range that covered several orders of magnitude; and (5) an analytical cost and turnover time commensurate with the analysis of several thousands of samples in a few months. The approaches developed included: enumeration of bacteria labeled with a vital fluorescent stain (CFDA/SE) using microplate spectrofluorometry, flow cytometry, and ferrographic (immunomagnetic) capture; enumeration of highly (13)C-enriched bacteria using combustion-IRMS; and quantitative PCR. These methods were compared to direct microscopic enumeration and plate counts during a bacterial transport experiment performed in an intact sediment core and designed to simulate the field experiment. Four of the seven methods had equivalent recoveries for the breakthrough of a pulse of bacteria eluting from a 50-cm long sediment core, and all of the methods detected the arrival of cells in the effluent prior to the conservative tracer. Combustion IRMS and ferrographic enumeration had the lowest quantification limits (approximately 2 to 20 cells/ml), whereas microplate spectrofluorometry had the highest quantification limit (approximately 10(5) cells/ml). These methods have the potential for numerous applications beyond tracking bacteria injected into the subsurface.     

Comparison of the trickling filter models for the treatment of synthetic dairy wastewater

This paper describes the design implications of four existing trickling filter models. Experimental data from the treatment of synthetic dairy wastewater was used to evaluate the kinetic parameters. The four trickling filter models were examined for their ability to model the present data. Among the four models studied, Kincannon and Stover model based on the independent variable of surface organic loading rate gave superior results compared to other models.     

Efficient methods for studying stochastic disease and population dynamics

Stochastic ecological and epidemiological models are now routinely used to inform management and decision making throughout conservation and public-health. A difficulty with the use of such models is the need to resort to simulation methods when the population size (and hence the size of the state space) becomes large, resulting in the need for a large amount of computation to achieve statistical confidence in results. Here we present two methods that allow evaluation of all quantities associated with one- (and higher) dimensional Markov processes with large state spaces. We illustrate these methods using SIS disease dynamics and studying species that are affected by catastrophic events. The methods allow the possibility of extending exact Markov methods to real-world problems, providing techniques for efficient parameterisation and subsequent analysis.     

Determination of population balances in a mixed culture by specific cell adhesion

Summary Specific cell adhesion can be used to monitor the population balance in a mixed culture. A mixture of twoEscherichia coli strains were separated and monitored based on their different expression of thelamB protein. The results are compared to those obtained by differential plate counts.     

Comparison of population dynamics between slow- and fast-growing strains of the rotifer Brachionus calyciflorus pallas in continuous culture

Summary The population dynamics of a slow- and a fast-growing strain of the rotifer Brachionus calyciflorus are compared. Rotifers were grown in steady-states, at various specific growth rates (), in both two-stage chemostat and turbidostat cultures on the green alga Chlorella pyrenoidosa. Population variables, including specific ingestion (I), loss (L) and filtration (F) rates, yield (Y), production (P) and half-saturation coefficient of growth (K _g), were calculated using a growth model based on saturation kinetics. I, L, F and K _g were shown to be higher and Y and P lower for the fast-growing strain. Differences between the two strains with regard to these variables may represent tradeoffs associated with the faster potential growth rate. Steady-state relationships between these values and for the fast-growing strain, however, deviated from model predictions which suggest a possible shift from carbon to non-carbon growth limitation.     

Interactions in a mixed bacterial population growing on methane in continuous culture

The growth of a mixed methane-utilizing culture in a continuous flow fermenter has been studied under both methane and oxygen limitation. Small additions of methanol have been shown to inhibit the methane-utilizing moiety in the culture and it has been shown that the Hyphomicrobium sp. in the mixed culture removes any inhibitory methanol. The interaction between the methane-utilizing Pseudomonas sp., and the Hyphomicrobium sp. has been explained and a model of the continuous mixed culture under oxygen limitation has been formulated. Qualitative predictions of transient phenomena by the model have been verified experimentally.     

Treatment of high strength organic wastewater by a mixed culture of photosynthetic microorganisms

The growth characteristics and nutrient removal fromsynthetic wastewater by Rhodobacter sphaeroides,Chlorella sorokiniana and Spirulinaplatensis were investigated under aerobic dark(heterotrophic) and aerobic light (photoheterotrophic)conditions. Both in terms of economy and efficiency,aerobic dark conditions were the best for wastewatertreatment using R. sphaeroides and C.sorokiniana, but light was necessary with S.platensis. Neither growth nor nutrient removalcharacteristics of the cells were affected insynthetic wastewater with as high as 10 000 ppmacetate, 1000 ppm propionate, 700 ppm nitrate and 100 ppmphosphate. Although R. sphaeroides and C. sorokiniana showed good growth in syntheticwastewater containing 400 ppm of ammonia, S.platensis was completely inhibited.When grown as a monoculture, none of thestrains could simultaneously remove acetate,propionate, ammonia, nitrate and phosphate from thewastewater. R. sphaeroides could remove allthe above nutrients except nitrate, but the rate of removal was relatively low. The rate of nutrientsremoval by C. sorokiniana was higher, but theorganism could not remove propionate; S.platensis could efficiently remove nitrate, ammoniaand phosphate, but none of the organic acids. A mixedculture of R. sphaeroides and C.sorokiniana was therefore used for simultaneousremoval of organic acids, nitrate, ammonia andphosphate. The optimum ratio of the cells depended onthe composition of the wastewater.     

Quantitative selective PCR of 16S ribosomal DNA correlates well with selective agar plating in describing population dynamics of indigenous Pseudomonas spp. in soil hot spots

We used a quantitative PCR method targeting 16S ribosomal DNA using competitive PCR for specific detection of indigenous Pseudomonas DNA in soil hot spots. The amount of Pseudomonas DNA corresponded to the number of culturable Pseudomonas bacteria on Gould's S1 agar. This represents the first use of PCR for quantification of indigenous bacteria in more than one sample of soil.     

Effects of environmental conditions on the nitrifying population dynamics in a pilot wastewater treatment plant

The effect of environmental conditions, especially ammonium concentration, on community composition and nitrification activity of nitrifying bacterial biofilms in a pilot wastewater treatment plant was examined. A decreasing ammonium gradient was created when four aerated tanks with suspended carrier material were serially fed with wastewater. Community composition was analysed using fluorescence in situ hybridization (FISH) probes as well as partial 16S rRNA and amoA gene analysis using polymerase chain reaction-denaturating gradient gel electrophoresis (PCR-DGGE) and sequencing. Fluorescence in situ hybridization probes identified at least five ammonia-oxidizing bacterial (AOB) and two nitrite-oxidizing bacterial (NOB) populations. A change in nitrifying community was detected in the tanks, indicating that ammonium was an important structuring factor. Further, we found support for different autoecology within the Nitrosomonas oligotropha lineage, as at least one population within this lineage increased in relative abundance with ammonium concentration while another population decreased. Absolute numbers of AOB and NOB growing in biofilms on the carriers were determined and the cell specific nitrification rates calculated seemed strongly correlated to ammonium concentration. Oxygen could also be limiting in the biofilms of the first tank with high ammonium concentrations. The response of the nitrifying community to increased ammonium concentrations differed between the tanks, indicating that activity correlates with community structure.     

Comparison of methods for rotavirus detection in water and results of a survey of Jerusalem wastewater

Methods for the detection of viable rotaviruses and rotavirus antigen in water were developed and compared. The methods included laboratory-developed enzyme-linked immunosorbent assays (ELISAs) with chromogenic and luminescent substrates, commercial Rotazyme and Enzygnost ELISAs, and an indirect immunofluorescent assay. Of the methods tested, the immunofluorescent assay and the Enzygnost ELISA were the most sensitive for the simian rotavirus SA-11. All of the methods were positive for human rotavirus from clinical specimens. Seeded SA-11 rotavirus was concentrated from water by absorption to and elution from Zeta Plus filters followed by organic flocculation. Interference with the assays by components of the wastewater concentrates was minimal for the ELISAs, although the undiluted organic flocs were cytotoxic for the immunofluorescent assay. A survey of Jerusalem wastewater was carried out over the course of 1 year, and samples were assayed for rotaviruses and enteroviruses. Although enteroviruses were found in almost all of the samples, all samples were negative for rotaviruses. The concentration of rotaviruses in the wastewater was thus below the detection limit of the method used.     

In-vitro compatibility evaluation of fungal mixed culture for bioconversion of domestic wastewater sludge

Six different fungal strains/isolates were selected after conducting a series of experiments of isolation and screening to evaluate their successful adaptation and growth to domestic wastewater sludge and its efficient bioconversion into compost. Two different fungi were grown in the same petri dish 4 cm apart in two culture media, potato dextrose agar (PDA) and malt extract agar (MEA). Fifteen different in-vitro interactions were studied and summarized according to five possible outcomes, i.e., mutual intermingling, partial mutual intermingling, inhibition at contact point, inhibition at a distance and replacement. The interaction of Trichoderma hazianum ^s Rifai with Phanerochaete chrysosporium 2094 was identified as mutual intermingling. The partial mutual intermingling of T. hazianum ^s with Mucor hiemalis Wehmer suggested compatibility of the two strains without showing any abnormal effects. Perhaps these two combinations may interact mutually in any mixed culture programme. The fungal strain Aspergillus versicolor Vuill performed as a strong repellent and all interactions exhibited deadlock/inhibition at a certain distance. The isolate RW-Pl 512 from the gill of a basidiomycete from a rotten wood stub actively replaced the strain M. hiemalis in in-vitro culture.