Showing papers in "Water Research in 1991"

TL;DR: In this article, a dynamic model of the clarification-thickening process is presented, based on the solids flux concept and on a mass balance around each layer of a one-dimensional settler.

TL;DR: In this paper, the authors reviewed the aqueous geochemistry of chromium, especially with reference to the recent work of Rai et al. (report EPRI EA-4544, 1986, Report EPRi EA-5741, 1988), and showed that the chromium content of natural waters is generally low whereas rocks exhibit a wide range of Cr concentrations.

TL;DR: In this article, current levels of understanding of the reactions and processes comprising sorption phenomena are discussed, as well as the forms and utilities of different models used to describe them, and the translation of these concepts into functional models for characterizing sorption rates and equilibria.

TL;DR: The aquatic safety of the anionic LAS is indicated, more so than for any other surfactant, and safety assessments for other major surfactants in saltwater and freshwater should be considered preliminary and limited until validated with corresponding exposure measurements and additional laboratory and field-derived chronic toxicity data for animal test species.

TL;DR: In this article, rate constants for the direct reactions of ozone with 45 potential organic drinking water contaminants, including solvents, haloalkanes, esters, aromatics and pesticides (such as alachlor, aldicarb, atrazine, carbofuran, 2,4-dichlorophenoxyacetic acid, endrin, glyphosate), have been measured in water in the presence of hydroxyl radical scavengers to minimize interfering radical chain reactions.

TL;DR: In this paper, the adsorption of two basic dyestuffs (Atrazon Blue and Maxilon Red) and two acids (Telon Blue, Erionyl Red and Telon Blue) onto maize cob was studied.

TL;DR: In this paper, an extrapolation method is presented for the evaluation of the effect of toxic compounds on all species in a community from single species tests on selected species representing the community.

TL;DR: In this article, the authors reviewed the factors controlling denitrification and described the evidence for denitification in the groundwater environment and concluded that artificial denitization as an above-ground process affords the best nitrate removal rates and process control.

TL;DR: In this paper, the photocatalytic oxidation of methylene blue, Rhodamine B, methyl orange and salicylic acid have been studied in the presence of immobilized titanium dioxide coated sand in a flat bed configuration illuminated with a 100 W medium pressure mercury lamp and sunlight.

TL;DR: The Pan American Center for Sanitary Engineering and Environmental Sciences (CEPIS), a specialized Center of the Pan American Health Organization/World Health Organization (PAHO/WHO), has conducted a Regional Program since 1981 for the development of simplified methodologies for the evaluation of eutrophication in warm-water tropical lakes/reservoirs of Latin America and the Caribbean as mentioned in this paper.

TL;DR: Combined at the maximum levels of the present Dutch water quality criteria these metals were severely toxic to D. magna and caused 50% mortality in Salmo gairdneri, the latter exposed for 60 days during embryo-larval development.

TL;DR: In this article, three sets of serum bottles were used for batch anaerobic degradation of lactate and acetate, and they were fed 1g 1−1 COD and 15.6 mM (1.5 g 1− 1) SO42− at the start of the experiment.

TL;DR: In this article, a 1 litre stainless steel autoclave at temperatures in the range of 150-180°C was used for wet air oxidation of aqueous solutions of phenol and substituted phenols.

TL;DR: There may be some risk associated with reuse of graywater when these pathogenic bacteria or viruses are being excreted by an individual producing the graywater, according to the data imply.

TL;DR: Particle size information derived from membrane separation of wastewater samples and quantification of solids and organic content is used to examine particulate contaminants in wastewater in terms of size distributions and biological treatability as mentioned in this paper.

TL;DR: This study was able to show that the production and consumption of lactic acid, and the moderate hydrogen inhibition and regulation of the acidic products of the acidogenic bacteria, can be successfully modelled.

TL;DR: In this article, the authors examined relationships between structural and compositional properties of dissolved organic matter (DOM) and partition coefficients (K p ) describing sorption of four model contaminants to DOM and the bioavailability of contaminants by Daphnia magna.

TL;DR: In this article, a budget model is developed to predict the long-term response of a lake to changes in its phosphorus loading, taking sediment-water interactions into account, and the model is applied to Shagawa Lake.

TL;DR: In this article, an approach was proposed to use the equilibrium partitioning (EP) method to derive a coherent set of quality criteria for aquatic systems, which refer to dissolved concentrations, the concentrations in the suspended particles, the total (dissolved + particulate) concentrations and the concentrations of the sediment.

TL;DR: It is suggested that some specially designed biological aerated filter (BAF), instead of a BAC bed reactor, may be used in advanced wastewater treatment and supported the authors' suggestion that the mechanism of the BAC process is basically a simple combination of biodegradation and carbon adsorption.

TL;DR: In this article, a mechanistic model based on the reaction of chlorine with model compounds was used to derive kinetic equations for trihalomethane (THM) formation as a function of the precursor and chlorine concentrations under controlled pH and temperature conditions.

TL;DR: In this article, a non-equilibrium steady state box model is reported, that predicts the fate of new chemicals in a conventional sewage treatment plant from a minimal input data set, written in an electronic spreadsheet (Lotus™ 123).

TL;DR: Axenic culture experiments on the organisms thought to be responsible for EBPR in activated sludge have not been done under conditions appropriate for replicating the phenomenon inactivated sludge, resulting in the full range of empirical observations in activatedSludge being duplicated in pure culture.

TL;DR: In this paper, an intermittent aeration process with an activated sludge unit was evaluated with typical wastewater from swine housing (total N/BOD5 ratios were 0.18, 0.31 and 0.45), in comparison with a conventional process (a conventional process, NLAP), under 0.50 kg m−3 d−1 BOD loading for each unit in bench scale.

TL;DR: In this paper, two surface water sources in the southwestern United States were studied in bench-scale experiments examining two trihalomethane (THM) precursor removal processes, activated carbon adsorption and ozone oxidation.

TL;DR: In this article, a series of batch digestion experiments was performed to evaluate the effect of elevated acetic acid concentrations on the degradation of propionic acid and vice versa, and it was found that increasing the concentration of either acid from low levels reduced the rate of its utilization.

TL;DR: In this paper, the effect of influent substrate concentration on particle size distribution of methanogenic granular sludge was studied in laboratory-scale UASB reactors fed with propionate as sole carbon and energy source.