Showing papers on "Wastewater published in 1984"

Complexation of heavy metals by extracellular polymers in the activated sludge process

Abstract: Raw industrial and domestic wastewaters are likely to contain persistent anthropogenic pollutants, one group of which, the heavy metals, is particularly hazardous. Therefore, these ma terials must be removed prior to effluent discharge to reduce the potentially harmful effects to both the ecosystem of the receiving watercourse and the public health.1 Englande and Reimers2 have stressed that adequate dilution capacity of receiving waters is important to minimize the adverse effects of effluents, especially in areas where water reuse is practiced. In the U.K., during the low flow period of 1976, 40% of the River Derwent consisted of effluent, mainly from industry3; in other areas with extensive water reuse, almost 90% of surface flow could be from wastewater effluents.4 Because of the nature of wastewater treatment processes, accumulation of mineral content is inherent in water reuse2; thus, considerable environ mental concern has focused on these nonbiodegradable and toxic heavy metals.5 By whatever method water quality control standards are used, the movement to reduce and ultimately eradicate aquatic pollution is likely to require increased restrictions on the discharge of metal-laden and other effluents.6 To comply with the standards, industrial effluents could be diverted from direct discharge to sewers, which could cause treatment plant perfor mance to deteriorate but which would improve the condition of receiving water. Thus, as standards are raised, wastewater treatment will contribute significantly to the maintenance of surface water quality. Particulate and precipitated material is removed by primary sedimentation, which generally accounts for up to 40% of the initial metal load.7'8 Forms of metal entering the biological treatment stage are predominantly soluble.9 Biological removal of soluble metals is critical because their overall retention depends on absorption by the activated sludge biomass.

Use of artificial wetlands to remove nitrogen from wastewater

Abstract: As demands for water continue to increase and new water sources become scarcer and more expensive to develop, water resource planners look for alternative methods, such as waste water reclamation, to increase supplies. The Clean Water Act of 1977 (PL95-217) encourages the use of alternative and in novative technologies for water reuse. The concept of using wetlands for cost-effective and energy efficient treatment of municipal wastewaters has been dem onstrated both in Europe,1,2 and in the United States,3-6 with some degree of success; however, to date there has been little literature published on the operational parameters and associated treatment efficiency of wetlands (either natural or artificial) spe cifically designed for the removal of certain problem constituents, such as nitrogen. The deleterious effects of nitrogen on the aquatic environment include the increased eutrophication of receiving waters, and the increased risk of methemoglobinemia in human infants where elevated levels of nitrate (N03) or nitrite (N02) nitrogen are present in drinking supplies.7 With regard to the latter case, the Committee on Water Quality Criteria of the National Acad emy of Science has recommended that N03-nitrogen (NO3-N) concentration not exceed 10 mg/L in public water supplies.8 Therefore, it is essential that whenever reclaimed wastewater is injected or percolated into a domestic groundwater supply for recharge, a treatment process be selected that is capable of meet ing drinking water standards (<10 mg/L NO3-N). The most successful procedure for the removal of nitrogen from wastewater is sequential nitrification-denitrification, whereby ammonia (NH3) is first oxidized to NO3 by chemoau totrophic nitrifying bacteria, and then reduced to the gaseous end products (nitrogen gas, N2 or nitrous oxide, N20) by denitrifying bacteria, which utilize N03 or N02 as respiratory electron acceptors to carry out the oxidation of carbonaceous organic substrates. Denitrifying systems for NO3 removal from secondary wastewaters, agricultural drainage waters, or contam inated groundwater supplies, all of which contain very low levels of biochemical oxygen demand (BOD)?and often require sup plemental organic carbon (methanol) to increase the carbon pool and stimulate denitrification. Ehreth and Basifico9 pointed out the importance of low-cost alternatives to methanol, the use of which can account for nearly 50% of the operation and maintenance costs of treatment.10 Gersberg et al.,11 described the use of pilot-scale (66-m2) ar tificial wetlands as biological systems for the removal of N03 from secondary wastewater effluents. This report describes stud ies with larger, demonstration-scale (820-m2) artificial wetlands, which removed nitrogen from secondary wastewater effluents. Methanol, or lower-cost alternatives such as mulched plant bio mass or blended primary effluent, were used as the carbon sources to drive the denitrification process.

Biofilm Fouling of RO Membranes—Its Nature and Effect on Treatment of Water for Reuse

Abstract: Increasing demand for domestic water has spurred renewed activity in the treatment of secondary municipal effluent to augment existing resources. Demineralization of pretreated wastewater by reverse osmosis yields safe, potable supplies, but microorganisms and chemical substances in the feedwater rapidly impede membrane flux, reducing plant efficiency and increasing treatment costs. The nature of biofilm development was studied at an advanced wastewater treatment plant in Southern California under low- and high-chlorine conditions, where close relationships were found between the accumulation of biochemical material and the loss of membrane premeability. High chlorine residuals damaged the membrane structure and reduced mineral rejection capacity. The demand for potable water continues to increase in Southern California, renewing interest in wastewater reclamation to bolster existing domestic water supplies. Forecasts for the next five to ten years estimate a continuing, rapid rise in demand for domestic water. Industry professionals are concerned about this increasing need and are taking steps to prevent shortfalls.

Role of resistance to starvation in bacterial survival in sewage and lake water.

Abstract: A study was conducted to determine the significance of starvation resistance to the ability of a species to survive in sewage and lake water. Tests were conducted for periods of up to 14 days. Rhizobium meliloti and one fluorescent and one nonfluorescent strain of Pseudomonas were resistant to starvation because their population sizes did not fall appreciably in buffer and sterile lake water, and the first two maintained high numbers after being added to sterile sewage. Cell densities of these bacterial species dropped slowly in nonsterile sewage, and more cells of these three organisms than of the other test organisms remained in nonsterile lake water. Rhizobium leguminosarum was moderately resistant to starvation because its numbers fell slowly in buffer and sterile lake water and did not change appreciably in sterile sewage. The abundance of Micrococcus flavus added to buffer and sterile lake water did not change, but the density of M. flavus declined in nonsterile lake water. The abundance of R. leguminosarum fell in nonsterile lake water and nonsterile sewage. Streptococcus faecalis, Staphylococcus aureus, an asporogenous strain of Bacillus subtilis, and Streptococcus sp. were susceptible to starvation because their populations were markedly reduced in buffer. Populations of the last three species declined rapidly in nonsterile and sterile samples of lake water and sewage. S. faecalis declined rapidly when added to nonsterile lake water and sewage and sterile lake water but not when added to sterile sewage, the persistence in the last instance probably being associated with the availability of organic nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)

An evaluation of single- and separated-phase anaerobic industrial wastewater treatment in fluidized bed reactors.

Abstract: Four fluidized bed reactors were used to evaluate single-and separated-phase anaerobic treatments of a high strength wastewater. Two reactors were fed with a synthetic wastewater, containing glucose as the primary carbon source, with a COD of 1.2 x 10(4) mg/L while the remaining pair were fed with a wastewater with a COD of 6000 mg/L. AT each influent strength, one fluidized bed reactor was operated as a single-phase system while the other was operated as a methanogenic reactor which was preceded by an acidification reactor in a separatedphase system. The reactors were operated under steady-state and variable process conditions. The separated-phase system consistently gave a better quality effluent with lower effluent suspended solids and total COD, and the methane yield was also improved. Under variable process conditions, the separated-phase system was inherently more stable and recovered more rapidly following a shock loading. Propionate and acetate degradation studies indicated that the biomass in the methanogenic fluidized beds of the two-phase systems was more adapted to volatile acid degradation than the biomass in the single-phase fluidized beds.

Anaerobic wastewater treatment

Abstract: The article reviews the present understanding of bacterial populations involved in anaerobic degradation of organic material into methane and CO2 (biogas); furthermore some recent process developments for anaerobic wastewater treatment are described It could be demonstrated that at least three groups of bacteria are involved in methanogenesis Hydrolytic and acidogenic bacteria first decompose the organic material into various organic acids, alcohols, hydrogen and CO2 The second group of bacteria convert these metabolites into acetic acid, hydrogen and CO2, which are then utilized by the methanogenic bacteria to produce biogas

Modeling volatile organic solute removal by surface and bubble aeration

Abstract: It has long been recognized that volatile solutes are transferred to the atmosphere during aeration in wastewater treatment.1"3 In particular, halogenated organic substances, including many purportedly hazardous substances, are transferred to the at mosphere at appreciable rates.4"10 The purpose of this paper is to present a methodology for estimating the removal of volatile organic solutes, especially halogenated compounds, resulting from aeration under typical conditions of wastewater treatment. The calculations are based on simple models that have been verified by Matter-M?ller et al9 and in our laboratory.11,12 The objective is to point out the influences of design and operation variables: for example, the general type of aeration process (sur face or bubble aeration), the amount of oxygen (02) transferred (grams of 02 per cubic metre of wastewater), and the oxygen transfer efficiency, as well as the importance of solute volatility. The model calculations presented are illustrative, and are not to be construed as accurate predictions for given conditions.

Process for deodorizing sludge

Abstract: Sludge, especially sewage sludge is deodorized, particularly to obtain the biomass by treating the waste water sludge (pollution sludge) with an active oxygen developing compound at 5° to 40°C.

Method of treating peroxide-containing wastewater

Abstract: It was found difficult to carry out anaerobic treatment of peroxide-containing wastewater. According to the invention, the problem is solved in that the peroxide content of the water is reduced in a catalytic pretreatment step (1), preferably an enzymatic pretreatment step.

Mutagenic 1‐nitropyrene in wastewater from oil‐water separating tanks of gasoline stations and in used crankcase oil

Abstract: Wastewater collected from oil-water separating tanks of ten gasoline stations for a year was fractionated into diethyl ether-soluble neutral, acidic, and basic fractions. Mutagenicity of these fractions was measured with Salmonella typhimurium strains TA98 and TA100 in the presence or absence of S9 mix. The neutral fractions showed high mutagenicity in the absence of S9 mix. Each neutral fraction was subjected to high-performance liquid chromatography (HPLC) and fractionated. A 1-nitropyrene(1-NP)-corresponding fraction was collected and analyzed by gas chromatography-mass spectrometry (GC-MS) and HPLC to prove that wastewater contains 1-NP and to quantitate 1-NP in wastewater. GC-MS patterns showed the following molecular and fragment ion peaks of 1-NP: 247, 217, 201, and 189. The amount of 1-NP in 36 samples of wastewater was 4.2-25,600 ng per liter of wastewater, and 1-NP accounted for 0.3-58.5% of the total mutagenicity of the neutral fractions. The other 19 samples of wastewater did not contain any detectable 1-NP. The mutagenicity of wastewater may be due to water from car washing and contamination by used crankcase oil. A Soxhlet extract of crankcase oil used in a gasoline was fractionated into three fractions as above. Mutagenicity was measured with strains TA98, TA100, TA98NR, and TA98/1,8-DNP6 in the absence or presence of S9 mix. The neutral fraction showed the highest mutagenicity with strain TA98 in the absence of S9 mix, and its mutagenicity was decreased in strains TA98NR and TA98/1,8-DNP6. The latter result indicates that the used engine-oil contained 1-NP and dinitropyrenes. Actually, the amounts of 1-NP and 1,6-diNP in used crankcase oil were 138 and 2.0 ng per ml of oil, respectively, and these concentrations accounted for 0.45 and 2.7%, respectively, of the total mutagenicity of the neutral fraction with strain TA98 in the absence of S9 mix. Moreover, the concentrations of 1-NP and 1,6-diNP in used crankcase oil of a diesel engine were 349 and 31 ng per ml of oil, respectively, accounting for 0.9 and 12%, respectively, of the total mutagenicity of the neutral fraction in the same assay system.

Nickel Removal from a Synthetic Nickel-Plating Wastewater Using Sulfide and Carbonate for Precipitation and Coprecipitation

Abstract: The uses of soluble sulfide and carbonate were evaluated to determine their effectiveness in reducing nickel in a synthetic nickel plating wastewater. Nickel is a toxic substance and is detrimental to aquatic and human health as well as the operation of biological processes in wastewater treatment. Using a series of jar tests, an optimum pH range for nickel removal from a synthetic wastewater was found to be 10.0–11.0. The optimum removal occurred at pH 11 where a residual total nickel concentration of 0.1 mg/L was obtained with a sulfide: nickel weight ratio of 2.0 and a carbonate: nickel weight ratio of 20.0. A similar degree of removal was achieved at pH 10 where a residual total nickel concentration of 0.2 mg/L was obtained with a carbonate: nickel ratio of 10.0 and a sulfide: nickel ratio of 0.5. A mathematical model of the synthetic system was produced by multiple regression analysis. The model predicted the sample data trends quite effectively.

Recovery of metal from waste water by chemical precipitation

Abstract: Metals are removed from waste water by chemical precipitation and filtration. The system is controlled by a control system responsive to an ion specific electrode and a pH responsive electrode in a manifold that recycles filtrate to a reaction tank where precipitation occurs.

Emission of organic air pollutants from shale oil wastewaters.

Abstract: The emission of organic compounds from shale oil waste waters was investigated by using headspace and purge and trap sampling followed by analysis by gas chromatography with mass spectral and flame ionization detection. The air above waste water samples held in closed containers contained relatively small amounts of organic compounds (ng/mL), while 3 orders of magnitude greater quantities were purged from the waste waters. Six waste waters exposed to large amounts of air emitted similar distributions of the same compounds, with aromatic nitrogen-containing compounds (primarily alkylpyridine isomers) accounting for 40-78% of the total emitted organics from a single waste water, ketones for 3-13%, phenols for 2-11%, and nitriles for 2-6%. Vaporized organic compounds accounted for 2-5% of the dissolved organic carbon for the three process retort waste waters, compared to 23-52% of the three gas-condensate retort waste waters. Air samples collected in and near a pilot shale oil waste water treatment facility displayed qualitative agreement with the results of purge and trap analyses.

High rates conversions of soluble organics with a thermophilic anaerobic attached film expanded bed

Abstract: Anaerobic digestion has had limited application because of slow bacterial growth rates, relatively low organic removal ef ficiencies, and the sensitivity of the microorganisms to toxic materials, temperature, and pH. Over the last decade, however, interest in anaerobic digestion has increased. Recent efforts have emphasized: the fundamentals of anaer obic digestion; improvements of the more conventional tech niques such as digestion of animal waste and other agricultural residues and secondary wastewater sludge; reactor design.1-3 The anaerobic attached-film expanded bed (AAFEB) process, de veloped by Jewell and colleagues, was in fact a natural devel opment from existing processes and information on the fun damentals of process limitations.4 This process accumulates large quantities of microbial biomass (30 to 40 kg/m3 volatile solids (VS)), which in turn enables it to efficiently convert dilute sub strates (such as wastewater) to biogas, with minimum sludge yields.

Method of controlling an anaerobic treatment process

Abstract: The invention relates to a method of treating wastewater from the manufacture of peroxide bleached mechanical or chemi-mechanical pulp. The method comprises a hydrolysis step, a methane fermentation steps and an aerobic step. After the hydrolysis and methane fermentation steps, sludge is separated from the wastewater and partially recycled to the hydrolysis step. The redox potential of the outgoing water from the hydrolysis step is continuously measured and controlled to a value between -400 and -260 mV by regulating the amount of sludge recycled or by passing ingoing wastewater directly to the aerobic treating step.

Irrigation of Monterey Pine with Wastewater: Effect on Soil Chemistry and Groundwater Composition

Abstract: Fifteen-year old Monterey pine (Pinus radiata) was irrigated for 3 yr with wastewater derived from industrial and municipal sources. The wastewater contained high concentrations of Na²⁺ and HCO₃⁻ and was quite alkaline. Irrigation thus caused substantial increases in exchangeable Na²⁺, extractable P, exchangeable K⁺, pH, and the electrical conductivity of the soil solution. Highly colored organic compounds derived from pulp-mill effluent apparently combined with inorganic N from municipal effluent to form organic N compounds. Nitrogen remained largely in the organic form and became concentrated in the groundwater with colored humic compounds. The greatest environmental hazard in the use of such blended wastewater for irrigation is the contamination of drainage water with colored, saline water containing high concentrations of organic N. The organic compounds appeared to inhibit nitrification in the groundwater.

Method for anaerobic wastewater treatment

Abstract: The invention relates to a method of treating wastewater from closed manufacture of mechanical or chemi-mechanical cellulose pulp, which treatment is carried out in a hydrolysis and acid fermentation step and a methane fermentation step with subsequent sludge separation and recycling of separated sludge.