ISSN:1061-4303    

DOI:10.2175/WER.64.6.1

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
It was hypothesized that nutrient removal from wastewater could be achieved by using methane oxidizing bacteria (methanotrophs). Because methane is inexpensive, it can be used as an energy source to encourage bacterial growth to assimilate nitrogen and phosphorus and other trace elements. This initial feasibility study used synthetic nutrient mixtures and secondary sewage effluent as feed to a laboratory‐scale methanotrophic attached‐film expanded bed (MAFEB) reactor operated at 35°C and 20°C. The MAFEB system operated successfully at low nutrient concentrations under a variety of nutrientlimited conditions. Using a synthetic nutrient mixture with a nitrogemphosphorus feed ratio(w/w) of 9:1, phosphate concentrations were reduced from 1.3 mg P/L to below 0.1 mg P/L, and ammonia was reduced from 12 mg N/L to approximately 1 mg N/L on a continuous flow basis, with a bed hydraulic retention time of 4.8 hours. The average nutrient uptake rates from synthetic nutrient mixtures were 100 mg nitrogen and 10 mg phosphorus/L of expanded bed/d. Nutrient assimilation rates increased with increasing growth rate and with increasing temperature. Nitrogen/ phosphorus uptake ratios varied from 8 to 13, and the observed yield varied from 0.11 to 0.16 g volatile solids (VS)/ g chemical oxygen demand (COD). Nutrient removal from secondary sewage effluent was successfully demonstrated using sewage effluent from two local treatment plants. Nutrient concentrations of 10‐15 mg N/L and 1.0‐1.8 mg P/L were reduced consistently below 1 mg N/L and 0.1 mg P/L. No supplemental nutrients were added to the sewage to attain these removal efficiencies since the nutrient mass ratios were similar to that required by the methanotrophs. Removal rates were lower at 20°C than at 35°C, but high removal efficiencies were maintained at both temperatures. Effluent suspended solids concentrations ranged from 8 to 30 mg volatile suspended solids (VSS)/L, and the effluent soluble COD concentration averaged 30 mg/L.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.2

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Experiments were conducted to investigate the roles that activated carbon and synthetic ion‐exchange resins perform as support material for methanogenic phenol‐degrading consortia. The most important features of a support material, among those studied, were the availability of accessible pore volume and associated surface area for the colonization of microorganisms. The support material with the largest accessible surface area and pore volume, an anion‐exchange resin, possessed the highest adsorption capacity forl4C‐labeledPseudomonas aeruginosacells and supported the greatest number of methanogenic phenol‐degrading consortia on its surface, as observed by scanning electron microscopy. Activated carbon had a higher total surface area than the anion‐exchange resin but a smaller fraction was accessible to bacteria. The anion‐exchange resin exhibited a negligible capacity for phenol adsorption. A substantial decrease in the apparent rate of phenol adsorption by activated carbon coincided with substantial colonization of the activated carbon pores by bacteria. The capacity for phenol adsorption was also reduced over the duration of substrate draw and feed experiments. No substantial benefit to bacterial colonization was observed to arise from the phenol adsorption capability of activated carbon in comparison with the anion‐exchange resin.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.3

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
A recent study for the U. S. EPA documented more than 150 constructed wetland systems in the United States, treating municipal and industrial wastewaters. During 1990 and 1991, visits were made to more than twenty of these sites for observations and discussions with the designers and operators. This first generation of systems demonstrates a lack of consensus on design procedures, and in many cases little regard for some of the critical factors affecting performance. This paper summarizes the results of the inventory and site visits and provides suggestions for design of the second generation of these systems.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.4

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
The improvement in degradation of a hazardous chemical using a novel bioaugmentation scheme was studied. Bench‐scale offline batch enricher‐reactors (ERs) maintaining an enrichment culture were used to bioaugment bench‐scale continuous‐flow activated sludge reactors treating 1‐naphthylamine (1NA). In batch experiments, onetime bioaugmentation inoculations of 1, 2, 5, 10, 20, and 50% by mass of a INA‐degrading culture (mg mixed liquor volatile suspended solids [MLVSS] of INA‐degrading culture/mg MLVSS of indigenous culture) increased degradation rates by approximately 0, 33, 100, 100, 100, and 300% respectively over an uninoculated control. In continuous‐flow experiments, separate 13.7‐L reactors received daily inoculations of 1.4, 2.5, 6.6, 11.4, and 18.3% by mass of 1 NA‐degrading culture. Cumulative target compound breakthrough reduction following a 50 mg 1NA/L spike was 13, 21, 11, 35, and 41% compared to an unacclimated control and 4, 13, 1, 27, and 35% compared to an acclimated control, respectively. Similarly, the reduction in breakthrough during reacclimation to 5 mg 1NA/L over six days was 66, 73, 85, 98, and 100%, respectively. A 6% bioaugmented continuous‐flow reactor significantly reduced 1NA breakthrough following a step‐loading increase from 1 to 5 mg 1NA/L compared to an uninoculated control. Effective bioaugmentation was achieved with additions of biomass equivalent to 14‐25% of indigenous cell production rates.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.5

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
The biodegradation activity of activated sludge was characterized by the API‐ZYM and LRA‐ZYM Esterase test systems. These systems provide rapid, semiquantitative information on the activity of hydrolytic enzymes associated with the biodegradation of lipids, proteins, carbohydrates, nucleic acids, and xenobiotic chemicals. Activated sludge was collected from several municipal wastewater treatment plants (WTPs) which varied with respect to their operating parameters and influent wastewater composition. Sludge samples were separated into various fractions (mixed liquor, sonicated mixed liquor, freeze‐thaw, and extracellular fractions) and then assayed for enzyme activity relative to inactivated controls. Mixed liquor and freeze‐thaw preparations from all sludge samples displayed a wide range of enzyme activities, with phosphatase and aminopeptidase activities dominating. Hydrolytic activity was not observed in inactivated mixed liquor fractions, or in extracellular fractions prepared from any of the sludge samples collected. Sonicated mixed liquor samples displayed a wider range of enzyme activities than intact samples. A specific set of esterase (protein, lipid) and aminopeptidase (protein) activities found in mixed liquor fractions was also localized in freeze‐thaw preparations. In general, patterns of hydrolase activity were similar in sludges collected from the different WTPs, and decreased sharply in sludge samples incubated without aeration or nutrients for a 48‐hour period. Our results indicate that the API systems provide rapid, semiquantitative information concerning the hydrolytic enzyme profiles of activated sludge. This information is reproducible across different WTPs and can be useful in characterization of the physiological condition and biodegradation activity of activated sludge.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.6

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
The effect of molecular oxygen on the adsorptive capacity of activated carbon was evaluated in this study. It was determined that the capacity of granular activated carbon (GAC) foro‐cresol under oxic conditions can be more than 2.5‐fold the capacity attainable under anoxic conditions. This increase in the GAC adsorptive capacity under oxic conditions cannot be attributed to biological activity. The observed phenomenon was found to result from carbon mediated polymerization reactions ofo‐cresol that occur in the presence of molecular oxygen. The rate of adsorbate polymerization was slower than the rate of adsorption and the presence of molecular oxygen did not affect adsorption kinetics during the initial phase of adsorbent‐adsorbate contact. However, the presence of molecular oxygen was demonstrated to have a significant impact on the breakthrough ofo‐cresol from 5 GAC adsorbers operated in series (total bed length = 4 m, total GAC mass = 1 kg). During the first phase of the experiment, which was conducted under anoxic conditions, breakthrough ofo‐cresol from all 5 adsorbers was accurately predicted using a plugflow homogeneous surface‐diffusion model and independently determined kinetic and capacity parameters. Furthermore, the effluent profiles collected under anoxic conditions exhibited almost no tailing during the later part of breakthrough as saturation was approached. On introduction of oxygen to this system the effluento‐cresol concentration dropped significantly (from 200 mg/L to only 6 mg/L). The total exhibited GAC adsorptive capacity for the entire experiment was accurately predicted by the oxic adsorption isotherm.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.7

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Wastewater from an integrated bleached kraft pulp and paper mill was treated in seven parallel treatment trains. Each train consisted of three reactors in series, with the primary reactor (denoted LI) simulating an aerated equalization/stabilization lagoon with hydraulic retention time (HRT) equal to 1.5 days. The secondary (middle) reactor was different in each train. Three reactors (Rl, R2, R3) were operated at HRT = 4.5 days and the solids retention time (SRT) equal to, respectively 10, 20, and 40 days. The next three secondary reactors (R4, R5, R6) were operated at HRT = 1.5 days and SRT equal to 10, 20, and 40 days, respectively. The secondary reactor in the seventh train (R7) was operated at an HRT equal to SRT set at 1.5 days, that is, effectively operating as an aerated lagoon. The last, third or tertiary reactor in each of the series was operated as a settling lagoon with all reactors (denoted El to E7) having identical HRT = 1.5 days. All seven treatment trains have removed 5‐day biochemical oxygen demand (BOD5) down to 10 mg/L. The removals of adsorbable organic halides (AOX) and soluble organic carbon (SOC) were found to be directly proportional to the biomass concentration and the SRT of the process and were the highest in the R6 reactor with SRT = 40 days and highest mixed liquor suspended solids (MLSS) of 3320 mg/L. In the activated sludge reactors Rl to R6 the removals of AOX and SOC were found to be inversely proportional to HRT, that is, the removals were larger for the reactors R4, R5, and R6 which operated at HRT =1.5 days. Overall AOX removal was the highest (30%) in the train LI → R6 → E6, and the lowest AOX removal (21%) was in the train of lagoons LI → R7 → E7. The negative effect of increased HRT on the removal of AOX and SOC was explained by biosorption since at the same SRT, the lower HRT reactors contained more than twice as much mixed liquor suspended solids.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.8

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
Effects of continuous cultivation on the dynamics of heterogenous populations were investigated by employing a continuously stirred tank reactor (CSTR) with 100% cell recycle to minimize biomass waste and any shifts in microbial populations. Phenol was used as model substrate and as the sole carbon source. Activated sludge bacteria, acclimated to phenol, were grown in a CSTR with 100% cell recycle operated at the same dilution rate but with different influent phenol concentrations. During the steady state, the kinetic parameters for the Haldane model (µm,Ks, andK1) characterizing growth on phenol were determined by a long‐term batch experiment. The dominant microbial species at each steady state were analyzed by biochemical assays. There was a shift in microbial species at different influent phenol concentrations with a corresponding change in µmvalues whereas the values ofKsandK1were not influenced. Even though the changes in microbial populations and kinetic parameters were attributed to changes in the influent phenol concentration, there was no direct correlation between them.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.9

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:
A study was conducted to evaluate two chemical models of iron oxidation. The first model was proposed by U. S. EPA in 1983 for use in the design of acid mine drainage (AMD) treatment systems. This model expresses the oxidation rate as a function of ferrous iron, oxygen concentrations, and pH. The second model was proposed by the U. S. Bureau of Mines and expresses the oxidation rate as a function of a treatment system's oxygen transfer rate. The findings of the study were that the model based on oxygen transfer was accurate in predicting oxidation rates over a wide range of initial ferrous iron concentrations. The predictions of the EPA model were inaccurate in modeling iron oxidation.

ISSN:1061-4303    

DOI:10.2175/WER.64.6.10

出版商:Water Environment Research Foundation (WERF)    

年代:1992

数据来源: WILEY