摘要:

The neutralizing characteristics of MSWI bottom ash over a pH range between 4 and 12 were investigated using a reaction path model. Experimental data on the pH titration combined with the geochemical simulation were used to obtain the reacted fractions of the main constituents that are Ca hydroxide and carbonate and Al and Si oxides/hydroxides. The simulation results combined with the sensitivity analysis of the reaction system provided an insight into the neutralizing processes of MSWI bottom ash. The geochemical simulations showed the reactivities of major constituents of the solid waste in neutralizing reactions. In the most interesting pH range (pH4–12), the calcium‐containing constituents and carbonates made large contributions to the acid neutralizing capacity of the solid waste. The contributions of Si‐ and Al‐component to the neutralizing reactions were more complex, which could be explained by the interaction of multiple phases and equilibria in the system. Secondary phases played an important role in the neutralization reactions. Although the composition of individual secondary phases to a large extent was not known in detail, the system was robust in the sense that several possible secondary phases gave similar acid neutralization curves. Furthermore, they predicted similar aqueous phase concentrations. The predicted concentrations agree reasonably well with the experimentally found values.

ISSN:1093-4529    

DOI:10.1080/10934529809376770

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, the methodology used by the United States Environmental Protection Agency (EPA) to protect a small population that may be at high risk, referred to as the “maximally exposed individual”; (MEI) is assessed. Monte Carlo techniques and more reasonable values for exposure parameters are used to determine a more physiologically reasonable MEI. The Monte Carlo MEI is compared to the EPA's quantification of the MEI as well as the results of a standard MC assessment.

ISSN:1093-4529    

DOI:10.1080/10934529809376771

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Fenton's reagent, a strong oxidant, was evaluated for suitability to treat soils contaminated with 2‐methylnaphthalene (an aromatic compound), n‐hexdecane (an aliphatic compound) and diesel fuel (a complicated hydrocarbon mixture). Laboratory‐scale results show that Fenton's reagent reacts rapidly with these materials in soil, and will completely mineralize them if enough hydrogen peroxide is added. The effectiveness of the reaction at neutral pH indicates that it should be easier and more cost‐effective to apply this technology since no pH adjustment is required prior to soil treatment. Further investigation is required to identify the reaction mechanisms and optimize the parameters to attain the most cost‐effective full scale application of this technology.

ISSN:1093-4529    

DOI:10.1080/10934529809376772

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Free and calcium alginate entrapped cells of four microorganisms namelyPseudomonas aeruginosa, Pseudomonas fluorescens, Serratia sp., and Yersiniasp, have been examined for degradation of phenol, present in oil refinery effluent by observing growth and tolerance capacity against toxic effects of phenol. The study of tolerance capacity of all the four microorganisms for different sublethal concentrations have shown that phenol concentrations above 200 mg/l was toxic toPseudomonas fluorescens, while other three microorganisms tolerated phenol upto 400 mg/l. These four microorganisms were mixed for the formulation of microbial consortia and further used for the biodegradation of phenol present in oil refinery effluent. At bacteriostatic concentrations of phenol, toxicity effect has been found to be significantly lower in the case of immobilized bacteria in comparison to free cells. The immobilized microorganisms have been found to degrade 100% of phenol in 96 hrs., while the free cells degraded 80% phenol in 96 hrs. The oil refinery effluent's pollutional strength has been determined on the basis of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) tests besides the determination of phenol contents in various layers of oil refinery effluent. The immobilized mixed bacterial cells were able to degrade 37% of phenol present in oil refinery effluent within 6 hrs. The viability of the system is discussed in terms of its industrial application.

ISSN:1093-4529    

DOI:10.1080/10934529809376773

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effect of flue‐gas desulfurization gypsum (FGDG) on soil physical and chemical characteristics which influence leaching of nitrate (NO3‐) was investigated. Effects of FGDG amendment at 0, 4.5 and 9.0 Mg ha‐1on transport of nitrate (NO3‐), ammonium (NH4+), and bromide (Br) in a Candler fine sand were investigated in a leaching column experiment, with N application equivalent to 180 kg N ha‐1, as either calcium nitrate (CN) or ammonium nitrate (AN). The columns were leached with 2860 mL of water, equivalent to 65 cm rainfall. Cumulative amount of NO3‐N in 2860 mL leachate accounted for 61 and 72% of the total NO3‐N applied as CN and AN, respectively. Application of gypsum at 4.5 Mg ha‐1decreased the leaching of NO3‐from AN by 22% as compared to that without the application of gypsum. Total‐N recovery with or without FGDG accounted for 62 to 67% and 69 to 78% of total N applied as CN and AN, respectively.

ISSN:1093-4529    

DOI:10.1080/10934529809376774

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The Woodbine aquifer is an important source of groundwater in north‐central Texas. In a survey of 63 wells located within or near the aquifer's recharge zone, nitrate concentrations ranged from less than 0.22 mg/L to 102 mg/L. Only one observation exceeded 45 mg/L. In general, nitrate concentrations were higher in shallower wells, and there was no significant correlation between nitrate and chloride concentrations. Potential sources of nitrate in the study area include fertilizers used on crops and lawns, animal waste from feedlots, and household wastewater. Results of this study suggest that nitrate concentrations are locally elevated above background levels, shallow groundwater is more susceptible to nitrate contamination, and fertilizer is a probable source of groundwater pollution. The use of deep wells and careful land use planning may alleviate future contamination of groundwater supplies.

ISSN:1093-4529    

DOI:10.1080/10934529809376775

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, kriging analysis was applied in predicting and mapping for the contents of Cu, Cr, and Pb in a sampling area of Beijing's eastern farming regions irrigated with wastewater. Based on the kriging interpolation results, the pollution index maps of soil heavy metals were produced and the assessment of pollution was attempted. The results show that 56% of the surface soil of the sampled site was found to have been slightly polluted. The pollution indices of Cu, Cr and Pb were found to be the highest in the northeastern part of the sampling site, followed by the northern part and the southern part in descending order. The variations in pollution may be on account of specific distribution of wastewater outlets and also due to periodical utilization of contaminated sludge in the vegetable garden. Under these circumstances, the crops of the area were yet not substantially affected by these soil pollutants. It appears that immediate soil treatment or any remedial measures may not be necessary. However, it must be taken into account that a further irrigation with wastewater, especially increased utilization of contaminated sludge, could lead to greater accumulation of pollutants in the soil and create health hazards.

ISSN:1093-4529    

DOI:10.1080/10934529809376776

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A field study was conducted on a Decatur silty clay loam (clayey, kaolinitic, thermic rhodic paledult) soil field plots which received Huntsville and Chicago sludges at 20 Mg ha‐1for five consecutive years and also on field plots which received an single application of Chicago and Huntsville sludges at 100 Mg ha‐1over a ten year period. Indicator crops corn (Zea mays, L.) and sudangrass (Sorghum sudanenses, L.) were grown on these plots for one season to assess the availability to crops of residual P from sludge‐treated soils. The results of this study indicated that P accumulation in corn tissue was greater at the early clipping stage (39 days after planting). However, P accumulation was greatest at the milk to dough stage (79 days after planting). The extractable soil P in top 0–15 cm depth by using various extracting procedures generally followed the order of: Bray P‐1> Mehlich 3> Mehlich 1 > Morgan (before planting), and Bray P‐1 > Mehlich 1 > Mehlich 3 > Morgan (after harvesting). For all extractants, both Huntsville and Chicago sludges when applied at 20 Mg ha‐1yr‐1split treatments resulted in significantly higher extractable P than the single 100 Mg ha‐1treatment. However, the Huntsville sludge treatments generally resulted in higher P levels than the Chicago sludge treatments at each corresponding application rate. Regression analysis between tissue concentrations and extractable soil P concentrations indicated that the highest correlation (r=0.62**) for corn occurred with the Morgan extractant at the early clipping stage. However, for sudangrass the highest correlations were found with the Mehlich 1 (r=0.77**) and Bray P‐1 (r=0.74**) extractants, both also at the early clipping stage. This suggests that these extractants could be useful in predicting the P uptake by crops, especially when done during a specific stage of growth.

ISSN:1093-4529    

DOI:10.1080/10934529809376777

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A mathematical model characterizing the adsorption of odor on the surface of airborne dust in a ventilated airsapce is derived based on the concept of homogeneous surface diffusion of a complete mixing airflow system. The main scheme of the paper is to incorporate the age and size distributions of airborne dust into the diffusion model for evaluating the odor adsorption on the ambient aerosol. A closed‐form solution is presented here to allow a series of numerical experiments for investigating the effects of adsorption characteristics, the mean age of airborne dust, surface effective diffusivity, and dust particle size on the adsorption of odor to the existing aerosol. Results obtained show that the most favorable performance of a ventilation system in reducing odor concentrations is when the system model is operated underrp/ √Dsτ, < 1, in whichrp, is the radius of an airborne dust,D,, is the effective diffusivity of bulk odor in air, and τ is the mean residence time of airborne dusts in ventilated airspaces. The rate of adsorption of the odor to the existing ambient aerosol is also presented. The model enables engineers for evaluating the performance of the ventilation systems in reducing the odor emitted from stored manure in animal housing and can be used in the future to design the deodorization processes of a biofilter.

ISSN:1093-4529    

DOI:10.1080/10934529809376778

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The catalytic incineration of ethyl mercaptan over a MnO/Fe2O3fixed bed catalytic reactor was studied. The effects of operating parameters including inlet temperature, space velocity, C2H5SH concentration and O2concentration were characterized. Three kinetic models, such as power‐rate law, the Mars and Van Krevelen model and the Langmuir‐Hinshel‐wood model were used to analyze the results. A differential reactor design was used for best fit of kinetic models in this study. The results showed that the conversion of ethyl mercaptan was increased with an increase in the inlet temperature and a decrease in the space velocity. The conversion was lower at the higher concentration of ethyl mercaptan. The O2concentration had a positive effect on the conversion of ethyl mercaptan. C2H5SH had a poisoning effect on the MnO/Fe2O3catalyst, especially at a lower temperature. The Langmuir‐Hinshelwood model may be feasible to describe the catalytic incineration of C2H5SH. This suggests that the chemical adsorption of O2molecule is important in the process of catalytic incineration of C2H5SH.

ISSN:1093-4529    

DOI:10.1080/10934529809376779

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor