ISSN:1061-4303    

DOI:10.2175/WER.65.1.1

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

ISSN:1061-4303    

DOI:10.2175/WER.65.1.17

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

ISSN:1061-4303    

DOI:10.2175/WER.65.1.18

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
Thermal sludge conditioning liquor was successfully treated by a pilot‐scale upflow anaerobic hybrid system with an effective volume of 10.4 m3. The reactor was similar to the HYAN reactor in Lakeview but without a recirculation system. A gas‐solid separator was installed above a filter packed with polypropylene pall rings. The organic loading rate was increased stepwise to 30 kg chemical oxygen demand (COD)/m3· d. The hydraulic retention time was only 6 hours at the target loading rate.
More than 70% of soluble COD in the influent was removed, even at an organic loading as high as 30 kg COD/m3· d. Soluble 5‐day biochemical oxygen demand (BOD5) removal efficiency at the loading rate exceeded 95%. Volatile fatty acids concentration in the effluent was consistently less than 60 mg/L after the day when stable treatment had been obtained. The methane production fluctuated between 0.3 and 0.4 L/g COD removed. Solids production including effluent suspended solids (SS) was between 0.16 and 0.24 kg SS/kg COD removed.
The inside of the reactor consisted of two zones, a sludge blanket zone with less than 1% solids concentration and a sludge bed zone with 47% solids concentration. Although the reactor was seeded with an anaerobically digested sludge, granular sludge was produced in the reactor. The ratio of granules to the solids remaining in the reactor increased to approximately 70% at the end of the experiments. Most of the granules had diameters of less than 1 mm and their settling velocity was 0.6 cm/s or more. The granules were composed of bacteria likeMethanothrixaccording to SEM observations. The methane production rate was between 0.8 and 1.1 kg methane as COD/kg SS · d in an acetate solution.
According to substrates distribution in the reactor and tracer tests, the bed zone in the reactor worked similarly to a continuously stirred tank reactor (CSTR). Evaluation of soluble COD removal rates in the reactor indicated that the rate could be simulated by a Monod type reaction.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.2

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
Air stripping for the efficient removal of volatile organic chemicals (VOCs) from contaminated groundwater is used in drinking water purification and hazardous waste site remediation. As air quality regulations become more stringent, emission controls such as granular activated carbon (GAC) will be required on the air stripper offgases. Often air stripper‐GAC adsorber interactions are neglected with the air stripper design optimized and the GAC adsorber designed for the resulting offgases, leading to unrealistically high operating costs.
This paper presents a multicomponent offgas adsorption model which is used to calculate the carbon breakthrough curves. Due to its generality and ease of application, the Polanyi equilibrium potential theory is used to describe the equilibrium sorption isotherms. These are combined with the hydraulics and mass‐transfer kinetics to calculate chemical breakthrough curves. The model is calibrated using data from a pilot‐scale unit treating a contaminated groundwater containing seven chlorinated VOCs. Application of the model to temperature effects on GAC adsorber design and the impact of regeneration frequency on carcinogenic risk are presented.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.3

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
The feasibility of using less hazardous inducer compounds to maintain the ability of an enrichment culture to degrade a hazardous compound was investigated. Bench‐scale (5 L) batch enricherreactors (ERs) maintaining enrichment cultures were used to bioaugment bench‐scale continuous‐flow activated sludge reactors treating 1‐naphthylamine (1NA). Potential inducer compounds tested were 1‐acetatenaphthalene, 1‐naphthoic acid, 1‐naphthalene‐sulfonic acid, and gentisic acid. In batch experiments, subcultures of the original enrichment culture that had been grown on potential inducer compounds for a period of 3 months without 1NA, maintained the ability to degrade 1NA but at reduced rates compared to a control maintained on 1NA. In continuous‐flow experiments, separate 13.7‐L reactors received daily inoculations of 2–4% by mass of INA‐enrichment culture, or 3% by mass of the subcultures maintained on inducer compounds. Target compound breakthrough from augmented reactors was significantly reduced (relative to an acclimated control) following a step‐increase from 1 to 5 mg 1NA/ L, and reintroduction of 5 mg 1NA/L after its absence from the waste stream for 9 days (two separate experiments). A modest reduction of breakthrough was also observed following a 10 mg 1NA/L spike (a separate experiment).

ISSN:1061-4303    

DOI:10.2175/WER.65.1.4

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
A multilevel protocol has been developed to provide a consistent and repeatable means of determining fate and effect of toxic organic chemicals in anaerobic wastewater treatment processes. Level I consists of a three‐step screening protocol for assessing toxicant effect on organic cosubstrate transformations. Level II is a cosubstrate kinetics protocol designed to reveal the effect of toxic organic chemicals on the kinetics of acetogenic and methanogenic transformations. Level III is a toxicant degradation kinetics protocol. The protocol test approach represents a composite of conditions and procedures used by a number of investigators of anaerobic reactions. It permits a wide latitude in specific reactor sizes and types and in measurement techniques as long as the basic culture, chemical and physical environment, and substrates are maintained as prescribed. Examples are presented to illustrate the type of test results that can be expected when using the protocol.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.5

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
Treatment plant upgrades of existing facultative lagoon systems are rapidly incorporating constructed artificial wetlands systems to control biochemical oxygen demand (BOD) and total suspended solids (TSS). Subsurface flow wetlands or artificial wetlands filters (AWF) are being installed at many facilities throughout the U.S. Most of these systems are relatively new and extensive operational experience is lacking. This study presents an examination of the performance of a system at the U. S. Public Health Service's Gillis W. Long Hensen's Disease Control Center located in Carville, Louisiana. The AWF is designed to meet effluent standards of 10 mg/L 5‐day BOD (BOD5) and 15 mg/L TSS, based on a design flow of 568 m3/d (150 000 gpd) with a 24‐hour detention time. The AWF has a 0.69‐m depth of 2–8 cm rock with a 15cm pea gravel cap and swamp potato (Sagittaria latifola) and duck potato (Sagittaria falcata) planted on 30‐cm centers. The study was initiated in the spring of 1988 and samples were collected twice a week from seven sampling stations and analyzed for BOD5, flow rates, temperature, pH, TSS, and VSS. The results indicated that the AWF was effective at controlling BOD5and TSS within design standards over a range of hydraulic fluctuations of 163–871 m3/d (43200–230000 gpd). The AWF removed 62 and 76.5% of the influent BOD5and TSS, respectively. Analysis of samples taken from sample wells located in the first one‐third of the filter indicated 40 and 60% removal of BOD5and TSS, respectively. Step flow introduction of wastewater could better optimize filter bed volumes and maintain uniform plant growth. For new AWF systems designs, greater length to width ratios could achieve the same treatment while minimizing front end clogging and ponding problems.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.6

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
The impact of the characteristics of granular activated carbon (GAC) on adsorption capacity and on the potential for polymerization of phenolic compounds on the surface of GAC in the presence of molecular oxygen is evaluated in this study. Adsorption isotherm data were collected forp‐chlorophenol on five activated carbons; three manufactured from bituminous coal, one manufactured from lignite coal, and one manufactured from wood. These isotherms were collected under anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions. Higher extraction efficiencies of the carbons used in the oxic isotherms were obtained for the carbons that exhibited lower increases in capacities when compared to anoxic isotherms. Furthermore, no impact of the presence of oxygen on adsorption capacity was noted for the wood base carbon. Breakthrough curves developed forp‐chlorophenol on the five carbons studied have shown tailing effects for the carbons that demonstrated differences in capacities under oxic and anoxic conditions whereas no tailing was noticed for the wood base carbon.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.7

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY

摘要:

ABSTRACT:
The fate of volatile organic compounds (VOCs) in municipal activated sludge plants was investigated at pilot and full scale. More than 80% of the mass flow of nonchlorinated compounds was observed to be biodegraded while less than 20% was removed by stripping. Conversely, 46% of the mass flow of chlorinated compounds was biodegraded and 47% was removed by stripping. Adsorption of VOCs onto waste sludge was not a significant removal mechanism. The pilot plant employed was found to effectively emulate the liquid‐gas phase partitioning and overall compound removals observed in a full‐scale plant. Little difference in liquid‐gas phase partitioning was observed for coarse and fine pore diffusers in spite of differing mass‐transfer characteristics as demonstrated by oxygen‐transfer measurements. This implies that equilibrium between the liquid and gas‐phase concentrations was achieved with both diffuser types. Stripping of VOCs was observed to increase with airflow; however, the extent of stripping increased at a declining rate.

ISSN:1061-4303    

DOI:10.2175/WER.65.1.8

出版商:Water Environment Research Foundation (WERF)    

年代:1993

数据来源: WILEY