ISSN:1061-4303    

DOI:10.1002/j.1554-7531.1995.tb00153.x

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Design criteria for nitrification and denitrification of high‐strength wastewaters are presented in two upflow submerged filters in series. Oxygen was a very important parameter effecting the ammonia removal rate in nitrification. The half‐order and zero‐order rate constants for nitrification were determined for the dissolved oxygen ranges of 2 to 3 mg/L and 4 to 5 mg/L, respectively. The transition from ammonia to oxygen rate limitation occurred at a bulk oxygen:bulk ammonia ratio of approximately 2.5 to 4, showing that nitrification was oxygen limited for practical purposes. In nitrification nitrite accumulation reached a considerable degree at bulk oxygen:bulk ammonia ratios lower than 5. Also, in denitrification the half‐ and zero‐order rate constants were determined. The nitrite produced in the nitrification stage could be successfully reduced in denitrification without causing any inhibitory effect.

ISSN:1061-4303    

DOI:10.2175/106143095X131277

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

The kinetics of pathogen destruction were determined during storage of digested and dewatered wastewater treatment biosolids to obtain relationships between temperature and duration of biosolids storage. Biosolids, seeded withSalmonella typhimurium, Yersinia enterocolitica, Campylobacter jejuni, bacteriophage f2, poliovirus, andAscaris suumeggs were incubated at 5°, 22°, 38°, and 49.5°C, under both aerobic and anaerobic conditions for up to 62 days. Destruction of pathogens in stored biosolids occurred at all temperatures examined; however, rates increased with increasing temperature. There was no significant difference between the destruction of pathogens under aerobic or anaerobic conditions at all temperatures studied. At 50°C, the decay rate ofS. typhimurium, Y. enterocolitica,bacteriophage f2, poliovirus, andA. suumeggs was estimated to be 1.13, 1.10, 1.54, 0.81, and 0.21 log10reductions per day, respectively.

ISSN:1061-4303    

DOI:10.2175/106143095X131286

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Electrolytic respirometry was used to determine the biodegradation kinetic parameters of five volatile aromatic organic compounds: benzene, 1,2‐dichlorobenzene, 1,3‐dichlorobenzene, 1,4‐dichlorobenzene, and 1,2,3‐trichlorobenzene. A protocol developed earlier was modified to accommodate the volatile characteristic of the test compounds. Specifically, the model used in data analysis was modified using Henry's law constant to incorporate the effect of partitioning of a volatile substrate between the gas and liquid phases in a batch reactor. Similar kinetic parameters were obtained for benzene and its four chlorinated analogs. Substrate inhibition was observed in the case of 1,3‐ and 1,4‐dichlorobenzene, and intermediate product inhibition was observed in the case of 1,2‐dichlorobenzene. In addition, all chlorinated benzenes exhibited complete inhibition above certain threshold concentrations.

ISSN:1061-4303    

DOI:10.2175/106143095X131295

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

In this paper, the effect of fitting several different probability‐distribution functions to hydraulic conductivity or pore‐water velocity values, in the simulation of the movement of a nonreactive solute through the soil, is evaluated. The simulation of solute transport in the soil was found to be sensitive to the distribution fitted to pore‐water velocity. The log‐Gaussian (log‐normal) distribution, though traditionally used, is not necessarily the best distribution for characterizing the spatial variability of saturated hydraulic conductivity, pore‐water velocity, or infiltrability. The upper tails of the simulated relative concentration series are best fitted by beta distributions, regardless of the input distribution used for pore‐water velocity.

ISSN:1061-4303    

DOI:10.2175/106143095X131303

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

The release of polynuclear aromatic hydrocarbons (PAHs) from buried organic wastes into groundwater occurs over long periods of time. Estimation of the equilibrium aqueous concentration or “solubility” of PAHs in mixtures of contaminated soil and water can aid in predicting fate and transport processes. Four methods were evaluated for their effectiveness in predicting aqueous concentrations of 16 PAH compounds. The results indicated that a cosolvent method was extremely effective in predicting aqueous concentrations and that equilibrium models (Raoult's law) provided estimates within an order of magnitude of PAH concentrations in complex mixtures. Predicted concentrations from soil‐water partition coefficients (Kp) generally were within an order of magnitude of actual concentrations.

ISSN:1061-4303    

DOI:10.2175/106143095X131312

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Variousin situor pump and treat systems are used for the remediation and/or containment of groundwater. Tougher air pollution regulations have mandated the implementation of pump and treat strategies that minimize losses of organic compounds because of uncontrolled air stripping. A modified bench‐scale sequencing batch reactor (SBR) was intermittently closed to test its flexibility and applicability as a system for the treatment of Jet Fuel‐4 (JP‐4)‐contaminated groundwater associated with free product recovery. The SBR was operated for 180 days on JP‐4‐contaminated water that contained high concentrations of monoaromatic hydrocarbons. Typically, the effluent contained less than 50μg/L of total petroleum hydrocarbons with much lower levels for the benzene, toluene, ethyl benzene, and xylenes and met the discharge levels required by most state regulatory agencies.

ISSN:1061-4303    

DOI:10.2175/106143095X131321

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Transformation of wastewater organic matter during 3 hours of transportation in an intercepting gravity sewer was measured. Dissolved and particulate fractions in terms of the specific organic pools: carbohydrate, protein, lipid, and volatile fatty acids were measured as well as dissolved organic carbon (DOC) and chemical oxygen demand (COD). The fate of dissolved organics in bulk water was the focus. Sampling was performed during dry weather periods, taking the residence time into account. The bulk‐water dissolved oxygen concentration was between 0.1 and 5 mg/L but relatively constant during each sampling period.
Considerable removal of dissolved organics took place, with dissolved carbohydrate and acetate as the primary compounds removed. In COD units, the maximum measured value of the total changes in carbohydrate, protein, and acetate was 20 mg/L·h at 15°C. The DOC removal rates were slightly higher than what could be explained by the total changes of the dissolved specific pools. The removal of dissolved carbohydrate was dependent on concentration level and temperature. Described as a first‐order reaction, the removal rate (k) for dissolved carbohydrate was 0.58 h−1and 0.27 h−1at 15°C and 8°C, respectively.
No net removal of particulate matter during transportation was found. There was evidence to conclude that growth of microorganisms took place because of a net removal of dissolved organics. From simple calculations, it was concluded that the possible removal of particles because of sedimentation during dry weather was in the same range as the growth.
The observed change in wastewater composition during transportation in a gravity sewer affected the quality and the quantity of the organic matter and may be of importance for the biological nitrogen and phosphorus removal in wastewater treatment because a considerable part of the easy degradable fraction was removed.

ISSN:1061-4303    

DOI:10.2175/106143095X131330

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Multiple use management of aquatic systems frequently involves conflicting demands from the various user groups. A 4‐year program designed to evaluate large‐scale artificial fertilization as a potential management tool for enhancing the forage and game fish populations of Lake Mead, a large Colorado River reservoir, generated considerable attention from both on‐lake and downstream water users. An extensive water‐quality monitoring program, undertaken as part of the fertilization experiment, demonstrated that the nutrient additions did not produce significant negative impacts on Lake Mead water quality from either a public health (that is, drinking water) or environmental perspective. One set of parameters, for example, hypolimnetic oxygen depletion and the relative abundance of blue‐green algae, exhibited no consistent response to the fertilizer. A second group of parameters did respond to fertilizer addition, but changes were both moderate and relatively short‐term. Examples in this group include chlorophyll, threshold odor number, and trihalomethane formation potentials.

ISSN:1061-4303    

DOI:10.2175/106143095X131349

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Corrosion of concrete sewers is associated with the biological oxidation of hydrogen sulfide to sulfuric acid by bacteria of the genusThiobacillus. Inhibition of acid production by these organisms, was investigated by challenging established cultures with a heterotrophic competitor under controlled conditions. Two‐organism competition experiments (T. thiooxidansorT. neapolitanusversus the heterotrophic competitor) were conducted in a bench‐scale, continuous‐flow, constantly stirred tank reactor. Results were sensitive to the influent nitrogen:carbon ratio. Under conditions designed to produce nitrogen‐limited growth, the numbers of thiobacilli were reduced 60‐ to 1 200‐fold after introduction of the competitor. Effluent sulfate concentrations, an indicator of acid production, dropped by 85%. Under carbon‐limited conditions, modest reductions in thiobacilli cell density and effluent sulfate concentration were observed. Microbial competition reduced acid production under the conditions of the experiment. The results suggest that strategies based on competitive displacement of thiobacilli to inhibit corrosion of concrete sewers may be feasible.

ISSN:1061-4303    

DOI:10.2175/106143095X131358

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY