Showing papers on "Effluent published in 1999"

What is river health

Abstract: Summary 1. Traditionally the assessment of river water quality has been based solely on the measurement of physical, chemical and some biological characteristics. While these measurements may be efficient for regulating effluent discharges and protecting humans, they are not very useful for large-scale management of catchments or for assessing whether river ecosystems are being protected. 2. Measurements of aquatic biota, to identify structural or functional integrity of ecosystems, have recently gained acceptance for river assessment. Empirical evidence from studies of river ecosystems under stress suggests that a small group of biological ecosystem-level indicators can assess river condition. However, physical and chemical features of the environment affect these indicators, the structure and function of which may be changed by human activities. 3. The term ‘river health’, applied to the assessment of river condition, is often seen as being analogous with human health, giving many a sense of understanding. Unfortunately, the meaning of ‘river health’ remains obscure. It is not clear what aspects of river health sets of ecosystem-level indicators actually identify, nor how physical, chemical and biological characteristics may be integrated into measures rather than just observations of cause and effect. 4. Increased examination of relationships between environmental variables that affect aquatic biota, such as habitat structure, flow regime, energy sources, water quality and biotic interactions and biological condition, are required in the study of river health.

On the performance of Ti/SnO2 and Ti/PbO2 anodesin electrochemical degradation of 2-chlorophenolfor wastewater treatment

Abstract: Electrochemical oxidation of 2-chlorophenol was studied at Ti/PbO2 and Ti/SnO2 anodes. The performance of the electrodes was evaluated in terms of faradaic yield and fraction of toxic intermediates removed during the electrolysis. Results showed that, although similar average faradaic yields were obtained using Ti/PbO2 or Ti/SnO2 anodes, the latter material is preferred because of its better ability to oxidise toxic compounds. An effective electrochemical treatment (ηF≅50%) may be accomplished, in which electrolysis at Ti/SnO2 can be stopped when, in spite of a relatively high COD, only a small amount of easily biodegradable oxalic acid is present in the effluent.

Genotoxicity of wastewater samples from sewage and industrial effluent detected by the Allium root anaphase aberration and micronucleus assays.

Abstract: The genotoxicity of wastewater samples from sewage, and industrial effluent from the Amritsar, India, area were investigated using the Allium micronucleus and anaphase aberration assays. Raw sewage samples and acetone extracts of the dehydrated sewage were use for treatment of the Allium roots. Industrial effluents were collected and stored in the form of sludge (semi-dried matter). The acetone extracts of the sludge samples were also used for treatment of the Allium roots. From the Allium root micronuclei tests on the sewage extracts, no significant increase in the number of micronuclei was found in comparison with negative controls. All the other extracts from industrial effluent showed positive responses both in the micronucleus and anaphase aberration assays.

Estrogenic potency of effluent from two sewage treatment works in the United Kingdom

Abstract: Rainbow trout were exposed for 3 weeks (in a flow-through system) to various dilutions of treated effluent (25, 50, 75, and 100%) from Harpenden and Chelmsford sewage treatment works (STW) during November 1994 and August 1996, respectively, and the induction of plasma vitellogenin was measured. Significant (p < 0.05) increases in plasma vitellogenin concentrations occurred in fish held in effluent from Harpenden STW at concentrations of 50% and above. At Chelmsford STW, the effluent appeared to be more potent, causing induction of vitellogenin in fish at concentrations as low as 25% (compared with 50% for the Harpenden effluent). Exposure to lower concentrations of effluent emanating from Chelmsford in April of the following year indicated that estrogenic activity was diluted to no-effect levels at this STW at concentrations between 12 and 25%.

Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant Pseudomonas putida strain.

Abstract: A mercury-resistant bacterial strain which is able to reduce ionic mercury to metallic mercury was used to remediate in laboratory columns mercury-containing wastewater produced during electrolytic production of chlorine. Factory effluents from several chloralkali plants in Europe were analyzed, and these effluents contained total mercury concentrations between 1.6 and 7.6 mg/liter and high chloride concentrations (up to 25 g/liter) and had pH values which were either acidic (pH 2.4) or alkaline (pH 13.0). A mercury-resistant bacterial strain, Pseudomonas putida Spi3, was isolated from polluted river sediments. Biofilms of P. putida Spi3 were grown on porous carrier material in laboratory column bioreactors. The bioreactors were continuously fed with sterile synthetic model wastewater or nonsterile, neutralized, aerated chloralkali wastewater. We found that sodium chloride concentrations up to 24 g/liter did not inhibit microbial mercury retention and that mercury concentrations up to 7 mg/liter could be treated with the bacterial biofilm with no loss of activity. When wastewater samples from three different chloralkali plants in Europe were used, levels of mercury retention efficiency between 90 and 98% were obtained. Thus, microbial mercury removal is a potential biological treatment for chloralkali electrolysis wastewater.

Fluorine abatement using steam injection in oxidation treatment of semiconductor manufacturing effluent gases

Abstract: An apparatus and process for abatement of halogen in a halogen-containing effluent gas, such as is produced by a semiconductor manufacturing plant utilizing perfluorocompounds in the operation of the plant. Halogen-containing effluent gas is contacted with water vapor in a thermal oxidation reactor to convert halogen species to reaction products that are readily removed from the effluent gas by subsequent scrubbing. A shrouding gas may be employed to separate the halogen-containing effluent gas from the water vapor at the inlet of the thermal oxidation reactor, to thereby prevent premature reaction that would otherwise produce particulates and reaction products that could clog the inlet of the reactor.

Impacts of the Reduction of Nutrient Levels on Bacterial Water Quality in Distribution Systems

Abstract: This study evaluated the impacts of reducing nutrient levels on bacterial water quality in drinking water. Two American Water System facilities (sites NJ102a and IN610) with histories of coliform problems were involved, and each water utility received two pilot distribution systems (annular reactors). One reactor simulated the conventional treatment conditions (control), while the other reactor was used to assess the effect of biological filtration and subsequent reduced biodegradable organic matter levels on suspended (water column) and biofilm bacterial concentrations in the distribution systems. Biodegradable organic matter levels were reduced approximately by half after biological treatment. For site NJ102a, the geometric mean of the assimilable organic carbon concentrations was 217 μg/liter in the plant effluent and 91 μg/liter after biological filtration. For both sites, plant effluent biodegradable dissolved organic carbon levels averaged 0.45 mg/liter, versus 0.19 to 0.22 mg/liter following biological treatment. Biological treatment improved the stability of free chlorine residuals, while it had little effect on chloramine consumption patterns. High bacterial levels from the biological filters resulted in higher bacterial concentrations entering the test reactors than entering the control reactors. On average, biofilms in the model systems were reduced by 1 log unit (from 1.4 × 105 to 1.4 × 104 CFU/cm2) and 0.5-log unit (from 2.7 × 105 to 7.8 × 104 CFU/cm2) by biological treatment at sites NJ102a and IN610, respectively. Interestingly, it required several months of biological treatment before there was an observable impact on bacterial water quality in the system, suggesting that the effect of the treatment change was influenced by other factors (i.e., pipe conditions or disinfection, etc.).

Photocatalytic oxidation of acetone vapor on TiO2/ZrO2 thin films

Abstract: The photocatalytic oxidation of acetone vapor on TiO2/ZrO2 thin films is presented in this study. Acetone conversion data collected using a non-circulating tubular reactor are analyzed using a general power law model and a Langmuir–Hinshelwood–Hougen–Watson (LHHW) model; the LHHW model provides a slightly better fit than the 1/2 order power law model. The effects of reaction temperature and relative humidity on the rate of reaction are presented. Using either kinetic model, increasing the reaction temperature from 30 to 77°C (in a dry feed stream) significantly increases the reaction rate constant at a 95% confidence level; however, increasing the temperature from 77 to 113°C does not have a significant effect. The addition of water vapor (50% relative humidity) to the feed stream at 77°C significantly increases the reaction rate constant at a 95% confidence level. Also, at three different temperatures and a single reaction condition, the conversion of acetone is enhanced in the presence of water vapor. No byproducts are detected in the effluent stream of the photocatalytically active reactor.

N2O Emissions from a Nitrogen-Enriched River

Abstract: Nitrous oxide (N2O) emissions from the South Platte River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994−1995. The South Platte River was enriched in inorganic N (9−800 μM) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N2O, and median N2O emission rates from the river surface ranged from less than 90 to 32 600 μg-N m-2 d-1. Seventy-nine percent of the variance in N2O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N2O emissions from the South Platte River were 2 × 1013−6 × 1013 μg-N yr-1. This amount of annual N2O emissions was similar to the estimated annual N2O emissions from all primary municipal wastewater treatment processes in the United States (1). Results from this study indicate that N-enriched rivers could be important anthropogenic sources of N2O to the a...

Advanced Oxidation of Synthetic Dyehouse Effluent by O3, H2O2/O3 and H2O2/UV Processes

Abstract: Ozonation, hydrogen peroxide combination with ozone, and UV light processes were investigated for the treatment of synthetic dyehouse effluent containing six reactive dyestuffs and their assisting chemicals. The decrease in DOC, UV - absorbance at 254 nm, decolourization kinetics, and acute toxicity towards the bioluminescent marine bacteria Vibrio fischeri were used to examine the treatment performance of these oxidation processes. Data indicated that in all examined processes rapid and complete decolourization could be achieved, but optimum oxidation conditions such as H2O2 dose and reaction pH had to be established for effective treatment. Toxicity of the samples decreased abruptly to non - detectable levels during the first minutes of all advanced oxidation processes. However, none of the oxidation combinations was able to bring about effective mineralization of the wastewater within 60 min reaction period. For comparative purposes, the electrical energy requirements per order of pollutant removal wer...

Wastewater effects on montmorillonite suspensions and hydraulic properties of sandy soils

Abstract: Recycled wastewater effluent is an important source of irrigation water in arid and semiarid regions. In these regions, however, irrigation water quality is one of the main factors limiting plant growth. Wastewater effluents generally contain high concentrations of suspended and dissolved solids, both organic and inorganic. Inorganic dissolved solids are only minimally removed from the effluent during conventional sewage treatment. As a result, most of the salts added during domestic and industrial usage remain in the irrigation water and may eventually reach the soil. A number of researchers have reported reduced hydraulic conductivity for soils to which treated wastewater has been applied. In this research, the influence of dissolved organic matter (DOM) contained in reclaimed wastewater effluents on the flocculation of montmorillonite and on the hydraulic properties of soils was studied. Flocculation values (FVs) for Na-montmorillonite increased with increasing concentrations of DOM at all pH levels analyzed. Maximum FV levels were exhibited for Na-montmorillonite at the highest DOM concentrations. The effect of DOM on FV can be explained by the mechanisms of edge-charge reversal and mutual flocculation. The hydraulic conductivity (HC) of a sandy soil was determined in the laboratory by leaching columns with an electrolyte solution chemically similar tomore » that of the wastewater effluent (but without DOM). In columns treated with wastewater effluent, the HC exhibited a sharp decrease to only 20% of its initial value. The adverse effect of DOM on HC was evident for this soil despite a relatively low exchangeable sodium percentage (ESP). The reduction in HC is likely to be the result of decreases soil pore-size, which reflects two processes: (1) retention of part of the DOM during water percolation; and (2) a change in pore-size distribution due to swelling and dispersion of clay particles. The latter may result from a higher percentage of adsorbed sodium combined with the presence of humic substances from the wastewater effluent.« less

Biological Phosphorus Removal, Its Role in Phosphorus Recycling

Abstract: At present the main types of phosphorus removal from wastewater effluents are chemical precipitation using alum or lime and biological removal. These methods of removal do not recycle phosphorus as a truly sustainable product because it is removed along with various other waste products. The development of phosphorus removal by crystallisation has provided a way of removing phosphorus in a form that has potential to be a raw material for the phosphate industry such as struvite and hydroxyapatite. Through combining biological phosphorus removal and crystallisation a number of benefits in terms of process economics can be made. By treating the effluent initially with a biological process a concentrated phosphorus effluent stream is produced. This concentration of phosphorus will significantly reduce the volume of effluent that needs to be treated which means that the crystallisation reactor size can be greatly reduced. This review describes the main types of commercial biological phosphorus removal technolo...

Soil Amendment with Distillery Effluent for Wheat and Rice Cultivation

Abstract: Distillery effluent contains a considerable amount of plant nutrients. In a field study soil amendment with diluted post methanation distillery effluent increased the yield of wheat and rice grown in sequence. Organic carbon and available potassium content of post harvest soils were also increased. Saturated hydraulic conductivity, bulk density and volumetric water content of the soils improved with effluent application. There was no change in pH after harvest of wheat and rice. The study showed that the effluent could be used as soil amendment. However, the EC of soil also increased indicating the possibility of salinity development in the long run with higher levels of effluent application.

Comparison of Escherichia coli, Total Coliform, and Fecal Coliform Populations as Indicators of Wastewater Treatment Efficiency

Abstract: Escherichia coli, total coliform, and fecal coliform population data were collected from two wastewater treatment facilities, a subsurface flow artificial wetlands, and a receiving stream. Results are presented from individual wastewater treatment process streams, final effluent, and river sites upstream and downstream of the treatment facilities. The QuantiTray technique with 4-methylumbelliferyl-β-glucuronide-based Colilert media was an effective method for quantifying E. coli and total coliform populations in these waters. Thermotolerant Klebsiella pneumoniae present in the effluent from one treatment facility interfered with recovery of fecal coliforms on m-FC media using the delayed-incubation membrane filtration technique. Klebsiella interference was not observed in the enumeration of E. coli by the QuantiTray technique. Both stream standards and discharge permits can be revised to apply E. coli as the indicator of fecal contamination. The results support development of E. coli-based effluent and stream standards to protect public health.

Silver speciation in wastewater effluent, surface waters, and pore waters

Abstract: Silver, inorganic sulfide, and thiol compounds were measured in municipal wastewater effluent, receiving waters, and pore waters from an anoxic lake sediment in order to predict silver speciation in these systems. The authors found submicromolar concentrations of inorganic sulfide even in fully oxic surface water. This inorganic sulfide is likely to exist in the form of colloidal metal sulfides, which have been shown to be stable under oxidizing conditions for periods of several hours. Inorganic sulfide in both the wastewater effluent and receiving waters was found to be 200 to 300 times in excess of silver concentrations, whereas inorganic sulfide in pore waters was 1,000 to 15,000 times in excess of silver concentrations. With sulfide in excess of silver, the authors predict silver sulfide complexes to dominate silver speciation. Thiols were present at low nanomolar levels in pore waters but were not detectable in wastewater effluent or receiving waters. Thiols do not appear to be important to silver speciation in these freshwater systems. Partitioning of silver into particular, colloidal, and dissolved size fractions showed that a significant proportion of silver is in the colloidal and dissolved phases. Dissolved phase concentrations were relatively constant in the treatment plant effluent and receivingmore » waters, suggesting that silver in the <10-kDa size fraction is strongly complexed by ligands that are not significantly affected by aggregation or sorption processes.« less