摘要:

Rate of petroleum hydrocarbon degradation was measured in sediment collected from a low energy brackish wetland site which had been exposed for a number of years to produced water discharge. Recalcitrant or higher molecular weight compounds were the primary hydrocarbon fractions found in the sediment. Degradation rates were determined by measuring loss of selected petroleum hydrocarbons components with time in laboratory incubation. South Louisiana Crude oil was added to the sediment to measure degradation rates of soluble hydrocarbons which were too low in concentration in the original sediment. Oxidized sediment conditions resulted in a higher rate of degradation for most hydrocarbons fractions as compared to reduced sediment. Fertilizer or nutrient amendments to contaminated sediments significantly increased rate of hydrocarbon degradation. Fertilizer enhanced the degradation of the lower and more soluble molecular weight fractions as compared to the higher molecular weight fractions.

ISSN:1093-4529    

DOI:10.1080/10934520009376951

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Barley and corn seedling were used to investigate the influence of zeolite and phosphogypsum on a) growth, photochemical activity of chloroplasts and chlorophyll content; b) content of water soluble Sr, Ca and Cd in the soil, and c) uptake of these elements in relation to photosynthetic activity, and content of these elements in the soil. Phosphogypsum was found to negatively influence the growth and development of the seedlings, affecting their morphological traits, biomass production and photosynthetic activity. Therefore, application of phosphogypsum combined with natural zeolite enabled a complete removal of the “side effects”; of phosphogypsum treatment. Furthermore, the application of zeolite was found to increase photosynthetic activity and biological yields of barley and corn plants. The results of our investigation showed the absence of close correlation between the content of water soluble Sr in the soil and its accumulation in plants. However, the uptake of Sr by barley plants was found to be highly dependent on their photosynthetic activity and leaf area.

ISSN:1093-4529    

DOI:10.1080/10934520009376952

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Accurate determination of kinetic coefficients, involving k (maximum specific degradation rate), Ks(half‐velocity coefficient), and Tc(transformation capacity), is critical for successfully modeling trichloroethylene (TCE) cometabolic transformation. This study evaluates the identifiability of these parameters for phenol‐oxidizing cultures degrading TCE with resting cells and formate addition, by using three approaches. The correlation coefficient between k and Ksis first calculated, then the contour lines in k and Ksparameter space are visually examined, and finally the identifiability of k/Ksand Tcis analyzed. Results concerning the uniqueness of these parameters for each culture in degrading TCE are interpreted and compared. Analysis results indicate that k is highly correlated with Ksin the three cultures with resting cells. The parameter can be more easily identified when formate is supplied as reducing power for TCE transformation. However, this improvement varies with the conditions in which the cells are cultivated: it is the greatest for both Suspended Cells and least for Attached Cultures. When used as two independent parameters in modeling TCE transformation, transformation capacity, Tc, and, the ratio k/Ksshow no correlation. Of these two parameters, the ratio k/Ksappears the more informative and the higher the correlation between k and Ks, implies a more identifiable parameter k/Ks.

ISSN:1093-4529    

DOI:10.1080/10934520009376953

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A respirometric method for determination of the readily biodegradable chemical oxygen demand (COD) concentration in a wastewater was developed, and used to study the effect of the anaerobic stage of a biological phosphorus (P) removal process. The sludge used was obtained from a laboratory scale activated sludge A/O (anaerobic/aerobic) process for biological P removal, fed with synthetic wastewater composed by glucose and peptone as carbon sources. Respirometric tests were made in an electrolytic respirometer. Wastewater short‐time biochemical oxygen demands were measured after anaerobic reactions using the sludge from the A/O process, and the readily biodegradable COD concentrations were then calculated. Several tests were made using different kinds of synthetic wastewater in order to know the accuracy of the experimental technique. These wastewaters were prepared using a constant COD level but different organic composition in order to change their biodegradability. The method was used to study the effect of the anaerobic period duration on the readily biodegradable COD concentration produced from a starch containing wastewater. A higher anaerobic retention time caused an increase in the readily biodegradable COD concentration. This determination can be useful to know the effectiveness of the anaerobic period and thus, the viability of the Biological Phosphorus Removal (BPR) process with slowly biodegradable wastewater.

ISSN:1093-4529    

DOI:10.1080/10934520009376954

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The experiments were conducted to investigate the sorption of arsenic from the groundwater onto kimberlite tailings, the mineral waste from diamond mining, in two phases ‐ batch studies and column studies. In batch studies, the effects of different factors such as pH, adsorbent dose and adsorbent size on the performance of kimberlite tailings were investigated. Adsorption kinetics and equilibrium isotherm studies were also carried out. The adsorption capacity of kimberlite tailings was calculated as 0.25 mg/g of adsorbent. In column studies, the performance of fixed‐bed kimberlite tailings was studied and the adsorption capacity was found to be 0.27 mg/g of adsorbent.

ISSN:1093-4529    

DOI:10.1080/10934520009376955

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The sole ozone used in cooling water treatment has raised some critical questions concerned with what happens chemically, that may describe why it can control corrosion, scale and microorganism. The pilot cooling tower (PCT) test presented the effects of ozone as a sole cooling water treatment. Except the higher pH and alkalinity in the PCT test, proper residual ozone concentration produced an oxidative film (protective film) on the metal surface of carbon steel, brass and type 316 stainless steel, the corrosion rate may also be decreased. Ozone was still unpredictable for scale control except for the existence of organic matter. The excellent control of fouling was also attained, that could be determined by the presence of ozone. The strong biocide properties of ozone resulted in excellent biological control. A mechanism is proposed to explain the results.

ISSN:1093-4529    

DOI:10.1080/10934520009376956

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Lanthanum hydroxide supported on alumina has been studied to sorb fluoride ion from aqueous solutions. The adsorbent is effective in decreasing fluoride ion concentration from 7 mM to 0.003 mM in the pH range 5.7–8.0. The rate constant for sorption was found to be 6x10‐2min‐1. The sorption of fluoride is Langmuir type and its capacity is 0.82 m M F‐/g of the adsorbent. The sorption selectivity shows that fluoride removal is affected by the presence of phosphate and sulphate but not affected by chloride, bromide iodide and nitrate ions. Alumina impregnated with lanthanum hydroxide has adsorption capacity in the range 0.340–0.365 mM/g. The removal of fluoride from industrial waste water is more than 96%. Fluoride ion sorbed can be eluted from the adsorbent with 10 mL of 0.1 M NaOH and the column can be reused after being conditioned with 10 mL of 1 mM hydrochloric acid. Results obtained by batch as well column methods are in good agreement with each other.

ISSN:1093-4529    

DOI:10.1080/10934520009376957

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper describes the development of a cost‐effective modified primary treatment method which can significantly increase the removal of both finely‐divided and soluble organic matter without resorting to the use of any chemical coagulants or secondary treatment method. It involves the recycling of a small portion of the settled primary sludge and then mixing it, after brief aeration, with raw sewage for a short period to induce biosorption and flocculation/enmeshment of various types of pollutants, thereby settling them together with the recycled sludge particles. During operation, the raw sewage is NOT subjected to any aeration; only a small aeration tank for sludge pre‐aeration and a flocculation tank for sludge‐sewage mixing are added; thus, the energy for the improved treatment method will not be too much higher than the conventional primary treatment method. Yet, the removal of both COD and SS can be improved significantly as compared to the conventional method. The increased removal is mainly attributed to the effective biosorption/flocculation and settling of colloidal particles and this suggestion has been substantiated by the data of particle analysis.

ISSN:1093-4529    

DOI:10.1080/10934520009376958

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:1093-4529    

DOI:10.1080/10934520009376950

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor