ISSN:1061-4303    

DOI:10.1002/j.1554-7531.1995.tb00160.x

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

The impact of anaerobic biological activity on the capacity of granular activated carbon (GAC) to adsorb organic compounds has not received much attention. In this study, the capacities of GAC for o‐cresol obtained from bottle‐point isotherm experiments were compared with the capacities measured in a completely mixed, biologically active, anaerobic GAC reactor treating a high‐strength synthetic wastewater containing acetic acid, phenol, and o‐cresol. O‐cresol was not biodegraded in the reactors and was removed solely by adsorption. Because of the low concentrations of phenol measured in the effluents from the reactors, no competition for adsorption between phenol and o‐cresol was observed. Also, the role of biological activity in the regeneration of GAC was demonstrated by preloading GAC with phenol and recovering the adsorbed phenol after the establishment of an active bacterial film on the GAC surface.

ISSN:1061-4303    

DOI:10.2175/106143095X133257

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

In a conventional rectangular flotation basin, acceptable separation efficiencies in excess of 90% can rarely be achieved with an operational surface loading in excess of 15 m/h, because of the great degree of dispersion, turbulence, and dead space present in the basin. A pilot‐scale coaxial cylinder‐type flotation column was built to fulfill the required plugflow performance, to reduce dead space, and to optimize the size. Using a step stimulus‐response test, it was observed that the column exhibits near‐plugflow performance within surface loading of 5 to 30 m/h. The influence of the air bubble cloud concentration in the stream on the degree of dispersion in the column was investigated. The performance of the pilot column has been verified for an industrial waste water under winter conditions.

ISSN:1061-4303    

DOI:10.2175/106143095X133266

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Oxygen microprofiles were used to evaluate the relationship between organic loading and respiration rate. The oxygen fluxes into the biofilms represent the total aerobic reaction rate of the biofilm, and the total organic removals represent the total use rate of the biofilm. The ratios of respiration rate to total chemical oxygen demand (COD) removal rate were evaluated under various operational conditions. Results showed that an increase in oxygen supplied increased only the respiration rate and did not affect the overall COD use rate. Systems fed additionally with azo dyes (possible inhibitors) had lower organic removals. Azo dyes appeared to affect both the local respiration rate and the local COD removal rate inside the biofilm.

ISSN:1061-4303    

DOI:10.2175/106143095X133275

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

A 5‐day survey was conducted at a municipal solid waste (MSW) cocomposter facility. The amount of volatile organic compounds (VOCs) in the MSW was indirectly estimated by measuring the concentrations of VOCs in gas, liquid, and solid phases and making necessary assumptions because of practical limitations in the direct measurement of VOCs in the MSW. Of the nine target VOCs tested, chloroform, toluene, methylene chloride, ethylbenzene, and trichloroethylene (TCE) were detected in descending order of concentration. Ethylbenzene, toluene, and TCE were detected once in the leachate at 24, 11, and 7μg/L, respectively. Ethylbenzene and toluene were detected in the rejected and screened compost at 5 to 25μg/kg on two sampling days. The dominant mechanisms of the VOC removal appeared to be volatilization and biodegradation. The average total input of the nine VOCs was estimated to be 385 g/d or 34 g/wet ton of MSW. The average VOC emission to the atmosphere was approximately 111 g/d.

ISSN:1061-4303    

DOI:10.2175/106143095X133284

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

The fate of six polynuclear aromatic hydrocarbons during anaerobic digestion of municipal sludges was investigated in a two‐stage pilot‐scale digester system. Primary digester removal efficiencies ranged from 23% for acenaphthene to 62% for acenaphthylene; secondary digester removal efficiencies ranged from 22% for acenaphthylene to 42% for phenanthrene. Most of the remaining mass of candidate compounds was present in the secondary digester waste sludge stream. Less than 2.5% of the candidate compounds entering the digestion system was present in the secondary digester supernatant. A dynamic model of the primary digester incorporating mixed first‐order biodegradation kinetics was calibrated for each of the candidate compounds. The biodegradation rate coefficients that were estimated for the primary digester ranged from 0.004 L/g·d for acenaphthene to 0.16 L/g·d for acenaphthylene. The biodegradation rate coefficient for acenaphthene did not significantly differ from zero.

ISSN:1061-4303    

DOI:10.2175/106143095X133293

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

The quantity ofAeromonasspp. andAeromonas hydrophilawas determined in samples of fresh surface water, brackish, and seawater with different degrees of pollution, and their presence was compared with the classical indicators of water fecal pollution.Aeromonasspp. were isolated from all the water samples examined and their number, like that ofAeromonas hydrophila,was always higher than, and in some cases correlated with, that of fecal coliforms. The results obtained seem to confirm the opinion already expressed by other researchers regarding the importance of monitoring the presence of these bacteria to obtain more complete information on the degree of contamination of surface water.

ISSN:1061-4303    

DOI:10.2175/106143095X133301

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

In this research, the effectiveness of various blending and sonication techniques were investigated for extracting particle‐associated coliforms from secondary effluent samples. The amount of shielding from ultraviolet disinfection afforded these coliforms by the particulates was then assessed. It was found that blending samples for 1.5 minutes at 19 000 rpm at 4°C in a mixture of chemicals (resulting in concentrations of 10−6M Zwittergent 3‐12, 10−3M EGTA, 0.01 M Tris buffer, 0.1% peptone, and pH 7) resulted in the greatest recovery of particle‐associated coliform, as detected by the multiple tube fermentation (MTF) test. Fragmentation of large flocs during homogenization, as evidenced by the change in particle size distribution, was most likely the responsible mechanism. Sonication proved ineffective. It was found that particle association and shielding of coliforms significantly affect accurate measurements of coliform density in secondary effluent using the standard MTF test and that significantly more coliforms may be present in disinfected secondary effluents than is indicated by the standard enumeration procedure.

ISSN:1061-4303    

DOI:10.2175/106143095X133310

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Groundwater contamination with nitrate (NO3−) is a current problem in the U.S. Sources of contamination include disposal of municipal biosolids. Because sorghum (Sorghum bicolor[L.] Moench) is an efficient scavenger of nitrogen (N) from the soil, its production on soils that receive biosolids may reduce N accumulation in those soils. An experiment was conducted to determine the amount of N accumulated by six types of sorghum. Three hybrids each of six types of sorghum (tropical, forage, sudangrass, sorghum × sudangrass, grain, and sweet) were evaluated for N accumulation on a municipal biosolids disposal site. Tropical sorghum and sorghum × sudangrass had the highest dry matter production and accumulated the most N. Nitrogen accumulation was largely a function of dry matter yield. Biomass produced was only adequate for beef maintenance diets but may be a useful biomass source for ethanol production from celulose.

ISSN:1061-4303    

DOI:10.2175/106143095X133329

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY

摘要:

Continuous‐flow anaerobic fluidized‐bed granular activated carbon bioreactors were used to treat 2,4‐dinitrotoluene (2,4‐DNT), a compound used in primary propellant production. A synthetic wastewater solution containing 2,4‐DNT, ethanol, mineral ether, and a carbonate buffer and another solution containing growth nutrients and vitamins were fed to each of the two bioreactors. The influent ethanol concentrations were varied to determine the effect of ethanol concentration on the extent of 2,4‐DNT degradation. The anaerobic bioreactors, when operated under methanogenic conditions with a primary substrate, were able to transform the 2,4‐DNT into 2‐amino‐4‐nitrotoluene (2‐A‐4‐NT), 4‐amino‐2‐nitrotoluene (4‐A‐2‐NT), 2,4‐diaminotoluene (2,4‐DAT), and trace amounts of toluene. During stable operation, for the range of non‐zero influent ethanol concentrations evaluated in this study, the majority of the products were identified as 2,4‐DAT. Batch activated sludge reactors were used to examine the fate of 2,4‐DAT under aerobic conditions. 2,4‐DAT (16 mg/L) were mineralized within 9 hours, indicating that a two‐stage system may be an effective 2,4‐DNT treatment strategy.

ISSN:1061-4303    

DOI:10.2175/106143095X133338

出版商:Water Environment Federation    

年代:1995

数据来源: WILEY