Showing papers on "Wastewater published in 1986"

Water treatment processes. III. Removing dissolved inorganic contaminants from water

Abstract: This article describes the physicochemical treatment processes typically used to remove the more common inorganic contaminants from water and wastewater. These are precipitation, coprecipitation, adsorption, ion exchange, membrane separations by reverse osmosis and electrodialysis, and combinations of these processes. The general criteria for process selection are discussed, and the processes and their typical applications are described.

Process and apparatus for the biological purification of wastewater

Abstract: In a process for the biological purification of wastewater, the wastewater is mixed with activated sludge in an aeration basin in the presence of carrier particles for microorganisms and is aerated with an oxygen-containing gas. Treated wastewater and free activated sludge are discharged from a discharge zone of the aeration basin downstream of an initial zone at least 20% up to 70% of the length of the aeration basin.

Equipment for treating waste water

Abstract: In the method of treating high-concentration organic waste water in dependence upon microorganism, waste water is first anaerobically treated in an anaerobic operation tank in dependence upon anaerobic bacteria groups and methane bacteria groups; in the second step, the waste water is further aerobically treated repeatedly in an aerobic operation tank, and an organic substance as hydrogen donor (raw waste water) is supplied to the aerobic operation tank before the succeeding aerobic treatment; in the third step, ozone treatment is effected to decolor the treated water. Two speed bacteria culture tanks for sludge bacteria and methane bacteria are provided separately to supply bacteria to the anaerobic operation tank for providing further reliable decomposition and denitrification of organic substance into methane and nitrogen gasses.

System for removing toxic organics and metals from manufacturing wastewater

Abstract: A system (10) is provided for treating wastewater discharged from airplane manufacturing operations. The system (10) includes a variety of sequential chemical adjustments to the waste stream which can remove substantially all toxic organics and heavy metals therefrom.

Health risks associated with wastewater irrigation: an epidemiological study.

Abstract: An analysis of morbidity was made in 11 kibbutzim (cooperative agricultural settlements), with a total population of 3,040, that had switched from nonwastewater to wastewater sprinkler irrigation or vice versa. Generally, partially treated stabilization pond effluent of poor microbial quality was used for irrigation. Vegetables or salad crops were not irrigated with effluent. The results showed that a seasonal, twofold, excess risk of "enteric" disease was found in the 0 to 4 year-old age group during the summer irrigation months in those years in which wastewater was used for irrigation, compared with the parallel summer months of nonwastewater irrigation years in the same kibbutz. On the year round rates basis, little or no excess enteric disease was found in wastewater irrigating communities.

Wastewater Treatment and Renovation by Different Duckweed Species

Abstract: The results of outdoor experiments with three different duckweed species grown in miniponds may prove to be highly competitive in comparison with those of existing secondary treatment methods. The duckweed biomass, with a crude protein content of over 30% of dry weight, may be used as a protein rich alternative fodder. The ease of duckweed harvesting makes the potential treatment system even more economically attractive. The treated wastewater is at an acceptable level and can be reused for agricultural irrigation. The range of organic loading for adequate performance of the duckweed was defined on the basis of outdoor studies. Organic loading in the miniponds was given by the ratio of COD and NH4+ in raw domestic sewage. This ratio was checked for three species of duckweed with varying retention times of the wastes in the ponds, and the protein production by the floating vascular plants was subsequently examined.

Effects of wastewater from olive processing on seed germination and early plant growth of different vegetable species

Abstract: The effects of wastewater from olive processing on seed germination and early plant growth of different vegetable species were examined Three types of wastewater at different concentrations were tested: raw wastewater, wastewater with organic matter removed and deionized wastewater Results generally indicate an inhibitory effect on seed germination and early plant growth by all treatments containing any kind of wastewater Of the three types of effluent, raw wastewater had the greatest depressive effect, followed by deionized wastewater and finally effluent with organic matter removed Barley showed the least sensitivity to phytotoxic effects while tomato was the plant most affected The remaining vegetable species showed an intermediate sensitivity

Comparative removal of toxic pollutants by six wastewater treatment processes

Abstract: Five pilot-scale wastewater treatment processes that provided less than secondary treatment - primary clarification plus filtration, chemical clarification, high-rate trickling filter, aerated lagoon, and facultative lagoon - were evaluated for removal of priority pollutants from municipal wastewater. A conventional activated sludge system was operated in parallel as a control. Wastewater feed was spiked with 21 organics dissolved in toluene. Removal of ambient concentrations of live metals was also evaluated. The control typically removed 80 to 90% of volatiles and 85 to 95% of semivolatiles. The facultative lagoon was the best alternative process, followed by the aerated lagoon. Removals of a specific toxic pollutant depended on the properties of the chemical and its interactions with removal mechanisms used in each treatment process. 9 references, 2 tables.

Modeling of the evolution of bacterial densities in an eutrophic ecosystem (sewage lagoons).

Abstract: The process of wastewater treatment was studied by modeling the relationships between physical, chemical, and biological (bacteria, phytoplankton, zooplankton) components of the sewage treatment lagoons of an urban wastewater center, based upon a two-year sampling program. The models of interactions between variables were tested by path analysis. The path coefficients were computed from the results of ridge regression, instead of linear multiple regression. The results show that fecal coliforms were effectively controlled by the environmental variables included in the model, which have a cyclic seasonal behavior. This control grew stronger with distance from the input (R2=0.71) to the output (R2=0.88) of the treatment plant, resulting in effective elimination of most enteric bacteria. Simultaneously, the ecosystem's community of aerobic heterotrophic bacteria became more independent from the model's predictive variables, with increased distance from the sewage input, thus demonstrating its maturation as an autonomous community in the lagoon ecosystem. Consequences of modeling are discussed, with respect to the understanding of biological wastewater treatment mechanisms and ecosystem dynamics and to plant management.

Method for application of wastewater to plants for improved wastewater treatment

Abstract: A method and means for application of wastewater to plants for improved wastewater treatment having an overhead distribution system for application of wastewater to plants. Purification of agricultural, commercial, domestic, mining and industrial liquid wastes by passage of said wastes through a shallow basin, pond, tank or the like covered with water or other species of Pontederiaceae, e.g. Pontederia spp., in particular, and other species cultured in a hydroponic mode in conjunction with or separately from Pontederiaceae, is accomplished by distribution of recycled liquid waste onto leaves and stems of the plants by spraying, sprinkling, splashing or the like. Depending on the quality and quantity of the wastewater, appropriate application rates, either intermittently or continuously, are utilized to effect positive contact of said liquid waste with living biota attached upon plants roots to attain greater treatment effectiveness and efficiency; to maintain aerobiosis in the root zone; and to, under a continuous application mode, exploit plants leaves as solid substrate for biofilm attachment so as to fashion a living filter that further improves system effectiveness, efficiency and cost worthiness.

Biological treatment of a landfill leachate in sequencing batch reactors

Abstract: A landfill leachate is treated, after mixing with chemical manufacturing wastewaters, by activated carbon adsorption. Biotreatment of the combined wastewater in sequencing batch reactors (SBRs) reduced the carbon requirement by 90%. Excellent treatment efficiency was consistently achieved under a variety of operating conditions: wastewater TOC, feed rate, hydraulic retention time, MLSS, organic loading, temperature, and cycle time. The SBR performance was unaffected when wastewater feeding was suspended during weekends and holidays. Results obtained in 1-L SBRs were reproduced in 12-L and 500-L units. The experimental data served as the basis for design of a full-scale SBR-adsorption system. The integrated wastewater treatment system would produce a better quality effluent at a lower overall cost. Biodegradation rates for some of the more persistent wastewater constituents were enhanced in batch bioreactors which were supplemented with strains of bacteria isolated from the landfill site.

Performance of SBR/denitrification with a primary sludge carbon source

Abstract: Biological denitrification has been shown to be the most re liable and cost-effective method of nitrogen removal from wastewater.1,2 Biological denitrification is the reduction of nitrate to nitrite and subsequently to nitrous oxide and dinitrogen gas (dissimilation) or to cell material (assimilation). This is carried out under anaerobic conditions by heterotrophic facultative bacteria in the presence of an energy and organic carbon source. Oxidized nitrogen removal can be achieved with separate or combined sludge systems. In combined sludge systems, carbon oxidation, nitrification, and denitrification processes are carried out by the same sludge in single or multiple reactors (without intervening reactors). The organic carbon necessary to drive de nitrification reactions is supplied from internal sources, mainly raw or settled wastewater, storage-induced carbon, and endog enous respiration of activated sludge organisms.3,4'5'6,7,8,9,10 Use of internal carbon sources can limit the overall nitrogen removal efficiency, however; raw wastewater introduces carbon, am monium, and organic nirogen.9,11,12 Use of endogenous carbon results in very low denitrification rates, and consequently, larger reactor volume requirements.2,5 These problems have been overcome with limited success by exposing the sludge to alter nating aerobic and anoxic environments. Carbon oxidation, nitrification, and denitrification processes can also be carried out in separate reactors using independent activated sludges (separate sludge systems). Nitrified effluents are usually deficient in organic carbon; therefore, external carbon sources must be supplied to drive the denitrification reactions. The most widely used external source is methanol, although nitrogen-deficient industrial wastes have also been used suc cessfully. Because of the optimum environmental conditions attained in each reactor, separate sludge nitrogen removal sys tems are very stable and nitrogen removal efficiencies are usually very high.13,14 A major disadvantage of separate sludge systems is the rising cost of external carbon sources, particularly meth anol. An alternate source of carbon that will circumvent some of the problems encountered in both separate and combined sludge systems is the carbon in primary sludge. Most of the carbona ceous and nitrogenous matter provided by primary sludge is present in paniculate form.15,16 Therefore, the feasibility of uti lizing primary sludge for denitrification will be governed by the relative amounts of carbonaceous and nitrogenous compounds hydrolyzed and the uptake rate of these compounds by the de nitrifying organisms.

Land application of municipal sewage sludge

Abstract: TREATMENT of municipal wastewater prior to discharge of relatively clean effluent involves a variety of processes designed to remove contaminants and pollutants. The residual material captured in the wastewater treatment process is a dilute suspension of solids called sludge. Sludge from municipal sewage consists mainly of biodegradable organic matter with significant amounts of inorganic materials. Because measurable quantities of heavy metals, toxic organic compounds, and pathogens (disease-causing microorganisms) are invariably present, disposal of sludge in an economically and environmentally acceptable manner is one of society's greatest challenges. Moreover, the sludge disposal problem continues to increase as treatment plants upgrade existing facilities to meet strict effluent discharge requirements. Most municipal sludge is now disposed of by land application, incineration, landfilling, ocean disposal, or lagooning. Land application, which is the controlled spreading of sewage sludge into or onto the soil surface, is becoming more popular as a sludge disposal option. According to the U.S. Environmental Protection Agency, land application accounted for disposal of 42 percent, by volume, of the municipal sludge generated nationwide in 1981 (8). This figure was up from 26 percent just five years earlier. Sludge is being applied to cropland, turfgrass, forests, and drastically disturbed land …

Chemical exergy of organic matter in wastewater

Abstract: (1986). Chemical exergy of organic matter in wastewater. International Journal of Environmental Studies: Vol. 27, No. 3-4, pp. 301-315.

Microbial aspects of wastewater reuse for irrigation

Abstract: In many arid environments an alternative source of water is needed to meet the growing demands of the community, agriculture, and industry, thus wastewater reuse has become a viable option. Although the use of wastewater for agricultural irrigation has been practiced for centuries, recently a conservative approach in fully utilizing this source of water has been taken. The uncertainty of the health risks to an exposed population through wastewater irrigation practices due to the possible presence of enteric pathogenic organisms is one of the major disadvantages. Pathogenic bacteria, parasites, and viruses are all found in sewage and may survive treatment processes. Once in the environment, many are able to exist for prolonged periods of time and outbreaks associated with wastewater irrigation have been documented. Epidemiological evidence is scarce, however, much has been done to determine the fate of the pathogens in the environment. The incidence, survival, and inactivation of pathogens in environments ...

Removing dissolved organic contaminants from water.

Abstract: The review is not exhaustive, but rather it focuses on four processes that appear to offer the greatest potential for general application in the water supply and wastewater treatment industries. These processes are chemical oxidation, a transformation process; air stripping, a liquid-gas separation process; two variants of a liquid-solid separation process, carbon adsorption and ion exchange adsorption; and two membrane separation processes, reverse osmosis and ultrafiltration. Figures 1 and 2 illustrate typical applications of these processes for water supply and wastewater treatment (4,5). The discussion of each process is complemented by a diagram and an example of typical application. Associated design considerations and features are presented in sidebars, each of which presents a set of equations that comprise a mathematical description, or model, of the process in question. 59 references, 6 figures.

Treatment of waste water by the activated sludge process

Abstract: An activated sludge treatment process for waste water characterized in that, in the waste water treatment where waste water containing organic matter is introduced into an activated sludge reaction tank and the excess sludge formed in the reaction tank is introduced into a sludge digestion tank to effect the digestion of said excess sludge by intermittent aeration with air, a part of the digestion tank liquid is passed through a filtration apparatus having an ultrafiltration membrane, the filtrate passed therethrough is withdrawn outside the system, the remainder is circulated to the digestion tank to maintain the liquid volume of the digestion tank at a definite level, and when the amount of the reaction tank liquid introduced from the reaction tank into the digestion tank is taken as W1, the digestion tank liquid is returned in an amount of (0.2-0.8)W1 to the reaction tank, and thus the amount of excess sludge to be treated outside the system can be reduced or can be completely eliminated.

Biotreatment of s-triazine-containing wastewater in a fluidized bed reactor.

Abstract: Mixed cultures of microorganisms immobilized on sand were used to degrade s-triazine-containing industrial wastewater in a fluidized bed reactor. Immobilized cell concentrations of up to 18 g/L volatile suspended solids could be achieved with the s-triazines as sole nitrogen source for growth and carbon sources added at a C--N ratio of about 12. Maximal removal efficiencies of 80% of the s-triazines could be maintained only if (a) the bio-film thickness was limited to avoid oxygen deficiency and (b) the carbon source and complete wastewater ( /=20-25 h.

Process for removal of fluoride and phosphorus-type contaminants from acidic wastewater

Abstract: A process for treating acidic process waste water containing SiF 6 2- is disclosed. The process is carried out by contacting the waste water with a strong base ion exchange resin and loading SiF 6 2- onto the resin. Phosphate ions are then removed from the waste water by raising the pH of the waste water to between about 5.0 and 7.0 and contacting the waste water with a strong base ion exchange resin and loading phosphate ions onto the resin.

Aquatic Plants and Wastewater Treatment (an Overview)

Abstract: The technology for using water hyacinth to upgrade domestic sewage effluent from lagoons and other wastewater treatment facilities to secondary and advanced secondary standards has been sufficiently developed to be used where the climate is warm year round. The technology of using emergent plants such as bulrush combined with duckweed is also sufficiently developed to make this a viable wastewater treatment alternative. This system is suited for both temperate and semi-tropical areas found throughout most of the U.S. The newest technology in artificial marsh wastewater treatment involves the use of emergent plant roots in conjunction with high surface area rock filters. Smaller land areas are required for these systems because of the increased concentration of microorganisms associated with the rock and plant root surfaces. Approximately 75 percent less land area is required for the plant-rock system than is required for a strict artificial wetland to achieve the same level of treatment.