Showing papers on "Wastewater published in 1975"

Environmental pollution and control

Abstract: Environmental Pollution Water Pollution Measurement of Water Quality Water Supply Water Treatment Collection of Wastewater Wastewater Treatment Sludge Treatment and Disposal Nonpoint Source Water Pollution Water Pollution Law Solid Waste Solid Waste Disposal Resource Recovery Hazardous Waste Radioactive Waste Solid and Hazardous Waste Law Air Pollution Meteorology and Air Quality Measurement of Air Quality Air Pollution Control Air Pollution Law Noise Pollution Noise Measurement and Control Environmental Impact Environmental Ethics.

Anaerobic acidogenesis of wastewater sludge.

Abstract: This paper has presented a general discussion on the theory and operating principles of the two-phase digestion process with special emphasis on the acidogenic phase of the total process. Stable, steady-state operation of the two-phase process is possible with wastewater sludge for extended time periods. It is possible to separate enrichment cultures of acidogenic and methanogenic organisms in isolated environments or phases by kinetic control involving manipulation of dilution rates and imposition of limits on the microbial generation time. Hydrolysis and acidification of waste water sludge are the predominant reactions in the acid-phase digester. Under mesophilic conditions, acidogenesis of activated sludge occurs at a pH value of 5.7, and an ORP.Ec, of -240 mV. Acidified activated sludge may be gasified efficiently in a methane digester at a detention time of 6.46 days. 7 figures, 7 tables. (DP)

Nitrification and denitrification processes related to waste water treatment.

Abstract: Publisher Summary This chapter describes the biological treatment of waste water, which is the largest application of continuous culturing of microorganisms. It discusses the biochemistry of nitrification and denitrification. Nitrification followed by subsequent denitrification is the easiest and most economical method currently available for removal of nitrogen from waste waters. The rate-limiting step in the overall process is usually the nitrification step, although this can be accelerated by the use of separate systems for carbon oxidation and nitrification. Denitrification is rapid as it is a respiratory process, yet the rate is frequently limited by the amount of available carbonaceous substrate needed for reduction of nitrate. Low temperatures cause the greatest problem in waste treatment of nitrogen and affect the reduction of nitrate to nitrite most drastically. Nitritification and denitritification represent an improvement over the general nitrification-denitrification procedure in terms of simplicity and time. The chapter describes environmental factors affecting nitrification and denitrification. It presents comparative waste treatment methods for both the methods.

Heavy metals uptake by acitvated sludge.

Abstract: MANY MUNICIPAL ACTIVATED SLUDGE plants receive combined wastewater containing heavy metals. These metals typically include copper, zinc, nickel, and cadmium and originate predominantly from industrial dischargers. Historically, there has been little concern for the pres ence of these metals in the wastewater, as long as they were at subtoxic levels. In creasingly stringent effluent regulations, to gether with recent indications of the detri mental effects of trace metal discharges on the receiving environment and its biota, have resulted in a need to assess the inter action and removal efficiency of heavy metals within the activated sludge process. There are numerous reports in the tech nical literature of soluble metal removal through the activated sludge process. Stones1_5 reported that activated sludge treatment reduced influent levels of iron, copper, lead, nickel, and zinc by 30 to 90 percent. Barth et al.6*7 reported removals comparable with those found by Stones for copper, nickel, and zinc. In studying the toxic effects of mercury on activated sludge, Ghosh and Zugger8 observed 51 to 58 per cent removal of the soluble mercury that was added to the mixed liquor and sug gested as a mechanism of removal either adsorption or incorporation into the cells. The complex and variable nature of com bined wastewater and activated sludge su pernatant suggests that a variety of soluble metal species may exist within the process. These may include, in addition to the free metal ion, complex species involving both organic and inorganic ligands. Because relatively little is known about the physical-chemical interactions between the activated sludge process and soluble metal ions, this study was undertaken to investigate the ability of the sludge to re move soluble metal species from wastewa ter and the affinity of the biological mass for selected heavy metals. The degree to which metal ions associate with the sludge determines the extent of reduction of solu ble metal in the supernatant and the con sequent effluent metal concentrations. A strong affinity between the sludge and metal, resulting in accumulation of the metal within the sludge, may enhance toxic effects that are not easily alleviated if the metal is tightly bound into the sludge. These toxic properties may carry over to digestion processes receiving excess sludge. Determination of sludge and supernatant association constants with heavy metals provides a useful tool for the assessment of physical-chemical interaction between the metal and the sludge. A cation-exchange technique, previously used by soil scientists to investigate metal-organic complexation in soil and its extracts, was used to deter mine the "apparent" stability constants of metal-supernatant and metal-sludge asso ciation.

Dynamics of nitrification in the activated sludge process.

Abstract: Renewed interest in the problems cre ated by the d scharge of nitrogenous compounds to receiving waters has focused attention on the form and concentration of nitrogen in wastewater treatment plant effluents. Most wastewater treatment plants are designed, operated, and evalu ated based on the reduction of carbona ceous 5-day biochemical oxygen demand (bod5), rather than on the total bod of the effluent (carbonaceous and nitrogenous). As a result, ammonium is the primary form of nitrogen in domestic wastewater treat ment plant effluents and is commonly found in concentrations up to 20 to 30 mg/1. If a theoretical oxygen requirement for ni trification of 4.5 mg oxygen/mg ammonium nitrogen oxidized to nitrate is assumed, an effluent with 20 mg NH4+-N/1 can exert a nitrogenous oxygen demand of up to 90 mg/1, which is considerably greater than that contributed by the ultimate car bonaceous demand of secondary biologi cal treatment plant effluents (?30 mg/1). The conversion of ammonium to nitrate within a biological treatment plant would, therefore, represent a significant improve ment in effluent quality. The activated sludge process may be used to obtain nitrification if conditions suitable for the retention and accumulation of nitrifying bacteria are maintaned. The conditions necessary for nitrification may be expressed in terms of sludge age, pH, temperature, and dissolved oxygen (do) concentration. The concentration of nitrifying bacteria will depend on their specific growth rate and on the rate at which they are discharged from the system through the effluent and waste sludge streams. Several laboratory, pilot, and full scale investigations have been conducted with nitrifying activated sludge systems and have demonstrated that high efficiencies of nitrification are obtained at sludge ages of approximately 4 days or more.1-6 It is important to note, however, that, at tem peratures less than 20 ?C, the sludge age required to maintain high nitrification ef ficiencies increases markedly. Until the recent application of mathe matical models based on kinetic principles, some of the basic concepts regarding ni trification in the activated sludge process were not clearly understood. Downing et al.1 were among the first to develop a kinetic model for nitrification in the acti vated sludge process. They concluded that consistent nitrification would be expected in activated sludge plants only if the growth rate of the nitrifying bacteria were greater than the rate of loss through the effluent and sludge wasting streams. Using this concept and experimentally determined values for growth rate coefficients, they were able to obtain reasonable predictions of the degree of nitrification in activated sludge plants.7 Although several mathematical models have been developed for the nitrifying ac tivated sludge process,1'3> 8_11 these usually have been steady-state models. Because domestic wastewater treatment plants op erate under time-varying loads, the use of steady-state models to describe these processes is inconsistent with their opera tional nature. In this regard, a full under standing of the kinetics of nitrification and the response of nitrifying systems to dy namic inputs may be necessary before more effective control of nitrification is possible. The primary objective of this research was to develop a dynamic model for nitri fication in the activated sludge process that

Process for treating waste water containing cellulose nitrate particles

Abstract: Total removal of cellulose nitrate particles from a waste water stream is accomplished by a combination of chemical and biological treatments which result in an effluent having a greatly reduced concentration of nitrogen compounds and having an acceptable BOD. The first step in the process requires that the insoluble, non-biodegradable cellulose nitrate particles be chemically digested with alkali to produce soluble products. Following digestion, the waste stream is supplemented with domestic raw sewage and a microbially utilizable carbon source and the supplemented waste stream is subjected first to an anaerobic microbial denitrification treatment to eliminate the oxidized forms of nitrogen and then to an aerobic microbial treatment to reduce BOD and to oxidize reduced nitrogen compounds. The effluent therefrom is again supplemented with a microbially utilizable carbon source and subjected to a final anaerobic microbial denitrification to remove nitrates present in the waste water resulting from nitrification processes occurring during the aerobic treatment step.

Removal of BOD and nitrogenous pollutants from wastewaters

Abstract: A multistage treatment is disclosed for the removal of carbonaceous BOD and nitrogenous pollutants from wastewaters, wherein the influent wastewater undergoes successive nitrification-denitrification in the presence of recycled activated sludge containing a mixed culture biomass comprising heterotrophic and autotrophic organisms. The initial mixing of the wastewater with recycled sludge is effected in the presence of sufficient oxygen to maintain oxic conditions. The mixed liquor from the initial oxic treatment, without intermediate separation of solids, is passed to an anoxic stage wherein nitrites and nitrates (NO x - , x = 2,3) formed by oxidation of ammonium compounds are reduced to nitrogen gas. Any number of oxic treating stages each followed by an anoxic stage may be employed. The final treating stage prior to solids separation from the mixed liquor may be either oxic or anoxic. The separated solids constitute the activated sludge recycled to at least the initial mixing stage. A short residence time, resulting in a high food to biomass ratio, is maintained in the initial oxic stage or the first subsection thereof, in order to avoid sludge bulking and to promote an active dense biomass.

Pilot-scale, high-rate biological dexitrification.

Abstract: considerable attention recently be cause nitrogen compounds are a cause of oxygen depletion in natural bodies of water, an inorganic nutrient for algal growth, and a danger to public health if present in excess in drinking waters. Ni trate nitrogen especially is a problem in areas where the receiving waters are used as sources for human consumption. This is the case in Nassau County, N. Y., where nitrates are increasing in subsurface water supplies.1 In conjunction with the Coun ty's plan to recharge wastewater into the groundwater table, a pilot unit was set up at the Bay Park Water Renovation Plant2 to denitrify the waste before recharge. The process used at this facility was based on the work of Jeris et al.,3 in which activated carbon was used as a support medium for biological growth. It is a biological process in which bacteria reduce nitrite or nitrate in the influent waste stream to nitrogen gas, a harmless non polluting end product. Wastewater passes upward in a cylindrical reactor through a bed of small particles, such as activated carbon or sand, at a velocity sufficient to cause motion or fluidization of all the medium. The medium serves as a support surface on which the bacteria grow. As wastewater containing nitrate or nitrite passes through the reactor, the bacteria on the medium reduce these compounds to nitrogen gas. The use of small particles, such as sand, provides a vast surface area on which the bacteria can grow and there by remarkably increases the amounts of contaminant that may be removed in a given volume of reactor. Fluidization of the medium increases the effective surface area, compared with that of packed beds,

Chlorine-containing organic constituents in chlorinated effluents

Abstract: Residual chlorine x from the chlorina tion of wastewater treatment plant effluents and other waters, such as cooling waters and industrial wastes, has biotoxic properties.2-4 Residual chlorine, however, does not include stable chlorine-containing organic compounds that may have been produced during the chlorination process.5-7 Relatively little is known about the forma tion of such compounds at the reaction conditions that exist during the chlorina tion of organic constituents at dilute con centrations such as those present in waste water treatment plant effluents.8-10 Asses ment in terms of biohazards, cumulative effects, and the socioeconomics of the total ecological impact of chlorination of waters requires qualitative and quantitative in formation concerning the formation of chlorine-containing organic compounds during the chlorination process with milli gram per liter concentrations of chlorine.2'11 The need for such information has become apparent with the recent determination of the detrimental ecological effects of cer tain chlorine-containing organic residues (for example, pcb, ddt, and ddt degrada tion products), which have now been found to be almost ubiquitous in the glo bal environment.12'13 This paper reports the results obtained by using a 36C1 tracer, high resolution Chromatographie method14> 15 to make a detailed examination of the chlorine-con taining compounds present in the chlori nated primary and secondary effluents from two domestic sanitary wastewater treat ment plants.

Renovation of waste water

Abstract: A waste water treatment system for the renovation of waste water includes a four stage treatment for removal of gross solids, suspended, colloidal and dissolved organic matter, dissolved nitrogenous material, phosphates odor, color, coliform and residual solids.

Die Einleitung von gereinigtem Abwasser in Seen

Abstract: Treated wastewater discharged into a lake should be introduced below the trophogenic layer. Tracing the marked wastewater by echosounding revealed that the usual discharge method is unsuitable. The wastewater flows more or less to the depth of its own density, which is usually in the trophogenic layer. If there is no movement, that is, current in the water body, the wastewater accumulates at the pipe's mouth. A continuous current is therefore an indispensable prerequisite for a wastewater discharge site. It is only when wastewater is mixed with at least five parts of lake water that it does not rise more than two meters.

Adsorption biooxidation treatment of waste waters to remove contaminants therefrom

Abstract: Suspended and dissolved biodegradable carbonaceous materials and nitrogenous materials present as contaminants in waste water, typically in raw domestic or municipal sewage, are substantially removed by a one-stage treatment. The waste water is contacted with a mixture of activated carbon and microorganisms, known herein as activated sludge, having molecular oxygen absorbed therein, which results in adsorption and biooxidation of the carbonaceous material, biooxidation of non-nitrate nitrogenous material to nitrate and depletion of the molecular oxygen whereupon biological reduction of the nitrate to nitrogen gases occurs. The nitrogen gases are vented and the resulting treated water is separated from the activated sludge. Regeneration of the activated sludge may be achieved by air stripping, after which the regenerated activated sludge material may be recycled. Further, the treated water may be subjected to clarification to complete the biological reactions and to remove residual suspended solids. The activated sludge from the clarification may be regenerated by air stripping followed by recycle of the regenerated material to the reactor.

Removal of heavy metal ions from wastewater

Abstract: Concentrations of undesirable heavy metals in industrial wastewater are reduced to below or very close to the most stringent aqueous discharge limits This is accomplished by forming an insoluble metal-polyelectrolyte complex which can be easily and economically removed from the effluent

Phosphate removal from BOD-containing wastewater

Abstract: Activated sludge wastewater treatment process for removing phosphate from BOD-containing wastewater in which phosphate-enriched sludge formed in the aeration zone is settled in a phosphate stripping zone under anaerobic conditions to cause release of phosphate from the sludge solids. The released phosphate is countercurrently stripped from the sludge in the stripping zone by a low phosphate, low solids stripping medium to provide phosphate-lower sludge for recirculation to the aeration zone.

Water and wastewater disinfection with ozone: A critical review

Abstract: (1975). Water and wastewater disinfection with ozone: A critical review. C R C Critical Reviews in Environmental Control: Vol. 5, No. 1, pp. 141-152.

Method for removing soluble selenium from acidic waste water

Abstract: Selenium is removed from solution in acidic waste water by treatment of the water with a metallic reducing agent. The invention is particularly effective for removal of selenium from zinc smelter effluent by reaction of the effluent with powdered zinc.

Methods and apparatus for treating wastewater

Abstract: This invention provides improved methods and apparatus for dissolving oxygen in wastewater treatment processes such as is required to satisfy the biological oxygen demand in the activated sludge process for the biodegradation of organic impurities. The invention enables attainment of high concentrations of dissolved oxygen with minimum consumption of oxygen and power. Wastewater with the high concentration of dissolved oxygen may be mixed with a larger volume of untreated wastewater to achieve the desired oxygen concentration and maintain volatile solids in suspension in the bulk liquid for optimum efficiency of purification.

Process and system for treating waste water

Abstract: A process of treating raw or primary waste water using a powdered, activated carbon/aerated biological treatment system is disclosed. Effluent turbidities less than 2 JTU (Jackson turbidity units), zero TOC (total organic carbon) and in the range of 10 mg/l COD (chemical oxygen demand) can be obtained. An influent stream of raw or primary waste water is contacted with an acidified, powdered, activated carbon/alum mixture. Lime is then added to the slurry to raise the pH to about 7.0. A polyelectrolyte flocculant is added to the slurry followed by a flocculation period -- then sedimentation and filtration. The separated solids (sludge) are aerated in a stabilization sludge basin and a portion thereof recycled to an aerated contact basin for mixing with the influent waste water stream prior to or after contact of the influent stream with the powdered, activated carbon/alum mixture.

Low-temperature biological denitrification of wastewater.

Abstract: Until recently, the approach to waste treatment was to ensure the removal of settleable solids, to reduce the bio chemical oxygen demand (bod), and to eliminate bacterial contaminants. In recent years, the advent of severe eutrophication problems has brought attention to nutrient control. Phosphorous, nitrogen, and car bon are the principal nutrients required by aquatic fauna and flora. It has been demonstrated that the growth limitation for algae may be the result of one or a combination of these nutrients. Extensive research into phosphorous removal tech niques has resulted in practical, economical processes for its removal from wastewater effluents. Nitrogen transformation or re moval is currently under investigation. The control of nitrogen in the aquatic environment is required for several reasons in addition to its role as an algal nutrient. The bod of municipal wastes may be sub stantially influenced by the presence of ammonia. The conversion of ammonia to nitrate requires 4.56 parts of oxygen for each part of ammonia nitrogen. The sig nificance of this oxygen demand is illus

Thermophilic microbiological treatment of high strength wastewaters with simultaneous recovery of single cell protein.

Abstract: Simultaneous removal of organic materials and recovery of protein in the form of bacterial cells from a simulated high strength biodegradable wastewater was studied using thermophilic aerobic microorganisms. A naturally occurring mixed culture of thermophilic microorganisms was obtained from soil, wastewater, hay, silage, etc. A chemically defined medium containing glucose along with other essential nutrients was employed as the feed. The kinetic behavior of the culture was studied in a continuous culture at an optimum temperature of 58 degrees C. Studies were were also performed on the effects of solids retention time (SRT) on the observed cell yield and the protein and ash content of the harvested biomass. An economic analysis of the process for single cell protein recovery was given.