Showing papers on "Wastewater published in 1989"

Biological wastewater treatment systems: theory and operation

Abstract: Wastewater characteristics and the effects of its discharge on receiving waters conventional wastewater treatment processes process fundamentals microorganisms exploited in wastewater treatment microbial energy generation the kinetics of bacterial growth modelling and design of biological reactors nutrient removal from wastewaters operation and control of conventional systems waste stabilization ponds and aerated lagoons.

Organic Waste Recycling

Abstract: Characteristics of Organic Wastes. Composting. Biogas Production. Algae Production. Fish Production. Aquatic Weeds and Their Utilization. Land Treatment of Wastewater. Land Treatment of Sludge. Planning, Institutional Development and Regulatory Aspects. Index.

Sorption of toxic organic compounds on wastewater solids: correlation with fundamental properties

Abstract: Sorption of toxic organic compounds on primary, mixed-liquor, and digested solids from municipal waste-water treatment plants was correlated with octanol/water partition coefficients and with modified Randic indexes. The correlations developed are useful for assessing the role of sorption in the treatment of toxic or hazardous compounds in conventional biological waste-water treatment plants. Correlations developed provide a basis for predicting the concentration of toxic compounds associated with waste-water solids at a given equilibrium concentration in the aqueous phase. Organics in sludge can impact anaerobic digestion, land spreading, incineration and ocean dumping of sludges. Estimates of the concentration of toxics in sludge allows assessment of the impact of toxics on sludge-disposal options.

Process for the biological purification of waste water

Abstract: A process and a plant for the purification of waste water wherein the waste water is alternatingly treated in the two treatment zones under anoxic and aerobic conditions and the waste water thus treated is subjected to an aerobic treatment in a separate zone before it is introduced into a clarification zone from which purified waste water and sludge is removed, at least a part of the sludge being recycled to the waste water which is introduced into one of the two treatment zones.

Process for treating wastewater

Abstract: The present invention entails a process for treating wastewater utilizing a return activated sludge process. Primary sludge is separated from the wastewater stream and conveyed into a fermentation tank and held a sufficient time to permit hydrolysis of suspended solids so as to produce soluble substrates. The soluble substrates are mixed with the return activated sludge and held for a selected time period to form conditioned return activated sludge. Thereafter, the conditioned return activated sludge is mixed in an initial aerobic treatment zone with pretreated wastewater. Thereafter, the mixed conditioned return activated sludge and pretreated wastewater is conveyed through a series of treatment zones, which may include at least one anoxic treatment zone, where phosphorus and other pollutants are removed from the wastewater.

Two-stage anaerobic/aerobic treatment process

Abstract: A two-stage process for purifying wastewater includes the steps of biophysical anaerobic treatment to remove the majority of the COD, followed by biophysical aerobic treatment to further purify the wastewater. A powdered adsorbent, preferably powdered activated carbon, is used with biological solids in each treatment step. Excess biophysical solids from the aerobic step are transferred to the anaerobic step for digestion. Fresh powdered adsorbent is added to the aerobic treatment step to compensate for that transferred to the anaerobic treatment step. Solids concentration in the anaerobic step is controlled by wasting solids to disposal.

Semi‐micro C.O.D. determination method for high‐salinity wastewater

Abstract: Semi‐micro determinations of the COD of wastewaters can err considerably if chloride is present. This article reports the degree to which accuracy is influenced by 1) COD itself; 2) the concentration of the masking agent HgSO4 in the digesting solution; 3) the presence of other salts, which is especially relevant in the case of water of marine origin; and 4) some of the other particular characteristics of the wastewater. Various experimental conditions are recommended for determination of the COD of different kinds of wastewater.

Fate of viruses during wastewater sludge treatment processes

Abstract: Infectious viruses are shed from humans by many routes. These include coughing and sneezing, contact with and aerosolization from external body lesions, urinary and intestinal excretions. Viruses shed by the latter two routes, urinary and intestinal excretions, are likely to be present as contaminants in domestic wastewater. The purpose of this review is to summarize recent information on the pathways which viruses follow during wastewater sludge‐generation processes and to examine information pertinent to the fate of viruses during wastewater sludge disposal. Information is included on viruses capable of causing human illness, as well as on bacterial viruses also present in wastewater, which, in some ways, may serve as indicators when assessing the likely fate of human viruses.

Particle Filtration for Wastewater Irrigation

Abstract: Conventional water filtration methods cannot be generalized for use in direct wastewater filtration for drip (trickle) irrigation systems. Effluents from an oxidation ponds‐reservoir system and from an activated sludge plant were filtered through granular beds and filter screens, for the purpose of evaluating particle filterability. The granular beds remove particles larger than 10μm with an efficiency of 40 to 85%, depending on the existence of surface straining and effluent type, whereas smaller particles (1-2μm in size) are hardly removed, suggesting that minimum transport theory applies. The removal ratio for all particles measured increases with grain size and with bed depth, and decreases with filtration velocity, affecting the lower particle size range more. Filter screens clog very rapidly even though they remove only about 1–2% of the total suspended solids (TSS). Both turbidity and TSS are inferior to particle size distribution measurements for filterability evaluation of wastewater effluents.

Domestic sewage as mixing water in concrete

Abstract: Reviews of the characteristics of domestic sewage and refinement in its composition upon biological treatment imply its suitability for use in concrete technology. A typical domestic sewage was characterized and used in this study as mixing water. Setting time, air content, specific gravity, and strength tests were performed on cement paste, mortar, and concrete specimens made with distilled water showed that untreated domestic sewage increases the initial setting time, entrains air, and reduces the strength of mortar and concrete, and therefore is not recommended for use in concrete technology. However, average biologically treated domestic wastewater is inistinguishable from distilled water when used as mixing water.

Process for the purification of industrial waste-waters

Abstract: The invention relates to a process for treating industrial waste water which comprises either: (a) pre-treating the waste water with at least two different pre-treatments selected from adsorption, membrane filtration and oxidation and then, biologically purifying the waste water or, (b) neutralizing and biologically purifying the waste water and then after-treating the waste water either by membrane filtration in combination with adsorption or oxidation or, by oxidation optionally in combination with adsorption or filtration on a nanofiltration membrane or, by filtration on a nanofiltration membrane.

Combined air and water pollution control system

Abstract: A bioaquatic air pollution control system for controlling both water and atmospheric pollution. The pollution control system includes an exhaust for directing polluted gases out of a furnace and a fluid circulating system which circulates fluid, such as wastewater, from a source, past the furnace where the fluid flow entrains the pollutants from the furnace. The combined fluid and pollutants are then directed through a rock/plant/microbial filtering system. A suction pump pumps the treated wastewater from the filter system past the exhaust to again entrain more pollutants from the furnace where they are combined with the fluid (wastewater) and directed to the filter system.

Process for the decomposition of explosive nitric acid esters dissolved in wastewaters

Abstract: A process for effecting thermal decomposition of explosive nitric acid esters in wastewater effluents of the explosives industry wherein no additional by-products are produced and wherein the danger of explosions is avoided In this process, the dissolved esters are exposed to a temperature of between 150° and 300° C under pressure lying above the boiling pressure of the wastewater During this step, the nitric acid esters are completely decomposed, and the wastewater treated in this way can then be passed on to further processing and purification In a preferred embodiment, the hot wastewater exiting from a decomposer unit is exploited for preheating the effluent before it enters the decomposer unit

Aquatic wastewater treatment using Elodea nuttallii

Abstract: The feasibility of using aquatic macrophyte-based aquatic treatment systems (ATSs) to treat wastewater in temperate climates was examined. Elodea nuttallii, Myriophyllum hetero phyllum, and Lemna minor were selected for study. E. nuttallii grew in primary effluent year-round, and effectively treated the wastewater to advanced secondary and possibly tertiary water quality levels. E. nuttallii-based systems that operated on a pilot scale continuous flow basis for 2 years were able to remove an annual average of 90% of the 5-day biochemical oxygen demand, (BOD5), 75% of the ammonia, 47% of the total nitrogen, and 38% of the total phosphorus from the primary wastewater. Control reactors without macrophytes removed 67% of the BOD5, 22% of the ammonia, less than 4% of the total nitrogen, and less than 19% of the influent phosphorus. Hydraulic retention times of 2.5 to 3.5 days were required in the E. nuttallii reactors. Removal rates were usually significantly correlated to plant biomass and productivity. J. Water Pollut. Control Fed., 61, 641 (1989).

Systematic characterization and chemical treatment of olive oil mill wastewater

Abstract: Classic and centrifugal olive oil mill wastewater volumes of 1.18 and 1.68m3/Mg olives and corresponding polluting loads of 37 and 53 Kg BOD5 and 82 and 121 Kg COD/Mg olives were established in a systematic study of 15 mills. Lime treatment at an optimum pH level near 11 requiring a dose less than 10g/l effected COD removals from 15 to 22% for classic and from 33 to 46% for centrifugal mill waste. The volume of resulting sludge was large and could not be adequately handled by sedimentation; the sludge had good dewatering characteristics and was amenable to simple straining. Excess lime treatment using up to 50 g/l lime offered little additional benefit.

Major ion content of urban wastewater: assessment of per capita loading

Abstract: Classical urban wastewater characterization includes mainly the determination of suspended solids (SS), organic matter, and nutrients. In some cases, a limited number of specific ion concentrations are determined, especially when the water will be reused directly for irrigation, groundwater recharge, or miscellaneous industrial uses. Very little information is available on the human input to aquatic systems of the major inorganic species (Na+, K+, Ca2+, Mg2+, S042^, СГ, Si, B, and total inorganic C) resulting from domestic water use. However, the potential increase of inorganic contaminants in ground and surface waters may limit the availability of water resources and induce detrimental changes in the aquatic environment. Moreover, major ion budgets are of prime importance in geochemical studies of element cycling and perturbation of these cycles by human activities. Furthermore, from the urban sanitation standpoint, supplied water volumes are still increasing along with urbanization and improvement of living standards. Current wastewater treatment processes provide no means for removal of the major dissolved minerals 1 and thus do not restore the chemical composition of the wastewater to that initially supplied. In the few investigations dealing with water reuse, the concentrations of major dissolved elements in wastewater are generally reported without reference to the water use. The occurrence of these ions is mainly attributed to the initial hardness or softness of the local water supply.2 Some authors have reported average concentration differences between initial water supplies and those resulting from domestic water use, both in Europe3 and the U. S.4 This approach unfortunately does not permit a comparison of data from different investigations, because the per capita water consumption varies significantly. A more quantitative approach consists of comparing the total flux of each major element in the wastewater with the total input flux in the water supply. A daily unit load for each element can be obtained by calculating the difference between these two total element fluxes and a knowledge of the population served in the drainage basin. These per capita values have been evaluated in the U. S.5 and Canada 6 for a limited number of ionic species. The same approach was applied in the present study.