Assessing unrecorded organic pollution from agricultural, urban, and wooded lands

An investigation was conducted of the organic pollution for seven small New Jersey watersheds representing agricultural, urban, and wooded lands. The 5-day biochemical oxygen demand (BOD) was used as a main index of organic pollution. Data obtained for a 2·5 yr period indicate background BOD concentrations averaging from 0·5 to 2·0 mg l⁻¹ in all streams, except that a value of 9·0 mg l⁻¹ was obtained for a residential-commercial-industrial area. During or after rainstorms, the BOD loadings, in pounds per day per unit area, averagely became more than ten times as the background amount for all streams. No significant correlation was found between BOD concentration and flow rate, but good correlations were obtained between BOD loadings and flows. The seasonal pattern of BOD loading distribution was examined. Also the frequency distribution of BOD concentrations and loadings were obtained.     

The treatment of leachates from domestic wastes in landfills—I: Aerobic biological treatment of a medium-strength leachate

A medium-strength leachate from domestic solid wastes in a landfill (COD 5000 mg l⁻¹, BOD 3000 mg l⁻¹ was treated using aerobic biological processes in continuous-flow, laboratory-scale reactors at low temperatures. Each unit was completely mixed, and mixed liquor was wasted such that solids retention time (SRT) was equal to the hydraulic retention period.At 10 C with addition of phosphate (COD:P less than 100:1) SRT values of 10 days were required to obtained well-clarified effluents, and high removal of BOD (>;98%) and COD (>;92%). Reduction of temperature to 5°C resulted in adverse effects on settling of sludges from units with SRT values of less than 10 days, but in other units good removal of organic materials could still be obtained. These units operated successfully with concentrations of mixed liquor volatile suspended solids (MLVSS) of 1450 mg l⁻¹, equivalent to a ratio of F/M of 0.21 kg BOD kg⁻¹ MLVSS day⁻¹ or less. Removal of ammoniacal nitrogen which took place (influent concentration 80 mg l⁻¹ as N) resulted from incorporation in biomass, and at SRT values of 10 days no nitrification took place at 5 or 10 C. Higher concentrations of ammonia in influent leachates resulted in ammonia in effluents when the ratio of BOD:N was less than about 100:3.6. Increasing the SRT of units to 20 days resulted in erratic conversion to nitrite, but reduced pH-values and possible simultaneous denitrification caused floating sludges and poorly-clarified effluents. Removal of ammonia is identified as a major problem when treating leachates, and further research is recommended.     

Nitrification kinetics in activated sludge at various temperatures and dissolved oxygen concentrations

Activated sludge from a domestic sewage works was enriched with nitrifying bacteria by running a laboratory fermenter on ammonia-supplemented sewage. This enriched culture was used to determine respirometrically the kinetics of microbial nitrification. It was demonstrated that the reaction fits the Michaelis-Menten model for temperatures from 10 to 35°C, having a temperature optimum at 15°C (K₃ 0.72 mg 1⁻¹ NH₃). Nitrification is unaffected by high dissolved oxygen concentration 38 mg 1⁻¹ O₂ at 30°C) after acclimatisation. Nitrite concentrations > 20 mg 1⁻¹ are inhibitory to the reaction.     

Thermal tolerance of zooplankton

First immature instar Daphnia pulex Leydig acclimated at 5, 10, 15, 20, 25 and 30°C, and Daphnia magna Straus acclimated at 10, 15, 20, 25 and 30°C, were instantaneously immersed at the specified temperatures which differed from acclimation temperatures by 10°C or more. Observations for mortality were made at regular intervals for 48 h or longer until at least one molting had occurred. Organisms acclimated at the same temperatures were also instantaneously immersed at 35°C, an ultimately lethal temperature, and followed to 95% mortality. Daphnia pulex acclimated at 20°C were stepped over varying rates of temperature change to 35°C and observed for mortality over a 48-h period. Thirty first immature instar organisms were used in each test, and tests were carried out in temperature controlled water baths and incubators. Filtered pond water was used for culture and testing.Both species survived instantaneous temperature changes over the entire normal tolerance ranges tested. Animals succumbed more rapidly upon instantaneous immersion at 35°C as the temperature at which they were acclimated decreased, with D. magna succumbing more rapidly than D. pulex from all acclimation temperatures. Daphnia pulex acclimated at 20°C and stepped to 35°C at varying rates of temperature change exhibited a decreasing 48-h mortality percentage as rates decreased from 6°C h⁻¹ to 1.33°C h⁻¹.Shortcomings in methodologies of previous thermal tolerance studies on zooplankton were discussed, and recommendations were made as to how these methods can be improved.     

Analysis of photosynthetic activity in the most polluted stretch of river Ganga

As a result of the increasing anthropogenic activities in the gangetic plain, Ganga water quantity as well as quality has declined over the years. A major effort to clean Ganga, named Ganga Action Plan (GAP) was instituted by the Government of India in 1984. The emphasis in GAP was on the reduction of organic load on the river through interception, diversion and treatment of wastewater reaching the river, thus maintaining the biochemical oxygen demand (BOD) and dissolved oxygen (DO) levels of river within the acceptable limits. A major criticism of GAP is that the significance of river ecology has not been addressed adequately during its conception and implementation. One of the important aspects from this perspective is the photosynthetic activity in the river Ganga. It has been postulated that photosynthetic activity plays an important role in maintaining high levels of DO in Ganga, and as a result the river can assimilate high organic loads without appreciable depletion in dissolved oxygen levels. Objective of the present study was to assess the photosynthetic activity and oxygen production rates in the river and correlate these values with various water quality parameters. Most polluted stretch of Ganga, which is known as the Kannauj-Kanpur stretch was chosen for this study. Based on the results of the study, it was concluded that despite implementation of phase I of GAP, and consequent diversion and reduction of organic loading to the river, both BOD and DO levels in the river has increased in the entire Kannauj-Kanpur stretch, except at Jajmau, where anaerobically treated effluent is discharged to the river. The nitrogen levels have also increased in the entire Kannauj-Kanpur stretch. Dissolved oxygen (DO) and alkalinity in the river water vary diurnally at all sites. Chlorophyll-a levels and oxygen production rates due to photosynthesis appear to be positively influenced by phosphate levels in the river water. Chlorophyll-a levels appear to be negatively correlated to the Ammonical and total Total Kjeldahl Nitrogen (TKN) content in the river water, suggesting the possibility of release of nutrients due to algal death and decomposition under certain circumstances.     

Psychrotrophic bacteria in sediments from the great lakes

The in vitro growth rates at 0°C of 8 representative psychrotrophs, isolated from Great Lake's sediment, ranged from k values of 0.047-0.022 h⁻¹ and generation times of 14.46-30.69 h. Faster rates were obtained at 15, 20 and 25°C, ranging from k values of 0.205-0.055 h⁻¹ and generation times of 3.38-12.48 h, with the optimum growth rate occurring at either 20°C or higher. Measurement of in situ microbial growth at 0°C in sediment columns by direct microscopy and protein-labelling fluorescent staining showed increases in microbial numbers of 10-fold when the sediment columns were amended with glucose, and 23-fold when amendment was with a more natural supplement, specifically, algal detritus. Determination of the number of viable microorganisms in the sediment columns again showed that considerable increases occurred at 0°C when glucose and detritus were added as substrates. Examination of the types of microbes occurring, during the growth conditions at 0°C when the substrates were added, by microscopy, and isolation of representative microbial types by replica plating showed that different populations responded to the two amendments.     

Modifications to electrolytic respirometer systems for precise determination of BOD exertion kinetics in receiving waters

Modifications to an electrolytic respirometric system are described which facilitate precise measurements of BOD progressions for low substrate concentration (BOD₅ < 20 g m^?3) as found in natural waters receiving organic enrichment. Samples may be incubated at any desired temperature or dissolved oxygen concentration with automatic hourly monitoring of the BOD progression. Subsamples may be withdrawn at any time without interference to the measurement. The system is independent of atmospheric temperature and pressure fluctuations and has a detection sensitivity of 0.05 mg of oxygen. Nomographs are presented to enable the maximum dissolved oxygen deficit, and the “apparent lag” time to be estimated. CO₂ removal, which may result in an extended lag phase, need not be used for BOD values below 50 g m^?3 provided adequate buffering is supplied.     

Acute toxicity and behavioral responses of coho salmon (Oncorhynchus kisutch) and shiner perch (Cymatogaster aggregata) to chlorine in heated sea-water

The acute toxicity and behavioral response to chlorinated and heated sea-water was determined for coho salmon smolts and 1–3 month old shiner perch. LC₅₀'s were determined for 7.5, 15, 30 and 60 min exposure times; 13, 16 and 20°C (Δt = 0, 3, 7°C) temperatures and total residual oxidant (TRO) concentrations ranging from 0.077 to 1.035 mg l⁻¹. The mean 60 min LC₅₀ for shiner perch was significantly reduced (P ≤ 0.05) from 308 μg l⁻¹ TRO at 13°C to 230 μg l⁻¹ TRO at 20°C. The 60 min LC₅₀ for coho salmon decreased from 208 μg l⁻¹ TRO at 13°C to 130 μg l⁻¹ at 20°C. The LC₅₀'s for coho salmon in chlorinated sea-water averaged 55% of those for shiner perch. The relationship between TRO concentration, exposure time, and percent survival in chlorinated sea-water at 13°C is presented for both species.A significant (P ≤ 0.01) avoidance threshold for coho salmon occurred at 2 μg l⁻¹ TRO and was reinforced with increasing temperature. A significant (P ≤ 0.01) avoidance threshold for shiner perch occurred at 175 μg l⁻¹ TRO, while a significant preference (P ≤ 0.05 or 0.01) response at 16°C and 20°C occurred at 10, 25, 50 and 100 μg l⁻¹ TRO. The ecological implications of the toxicity tests and the behavioral responses are discussed.     

Influence de sediments argileux incorpores au milieu d'insemination sur le succes de la fecondation chez la truite arc-en-ciel (Salmo Gairdneri)

The aim of this paper is to determine whether clay sediments suspended in water can prevent trout eggs from being fertilized. Kaolinite-rich clays (granulometric fraction: <2μm) (Fig. 1) were suspended in an artificial insemination diluent in doses ranging between 0 and 20 g l⁻¹. The eggs were exposed for 1, 10 or 20 min (experiment A) or inseminated (experiment B) in the diluent-sediment mixture. In experiment (C), the eggs were exposed to this mixture at three different temperatures (10, 15, 20°C). After insemination, the eggs were incubated for 10 days at 10°C and the percentage of eyed-eggs was used as an approximation of the fertility rate. The presence of clay sediments in the medium in which artificial insemination was carried out did not affect fertilization rate after the ovules had been exposed during 1 min to clay suspensions, at any of the temperatures used (8°C: Fig. 3; 10–15 or 20°C: Fig. 5) or at any of the sperm dilution rates (10⁻², 10⁻³, 10⁻⁴) (Fig. 3). On the contrary, there was a significant decline (P < 0.01) in the fertilization rate after the eggs had been exposed for 10 min at 8°C to doses of sediment exceeding 1.2 g l⁻¹ (Fig. 2). The fertilization rate also decreased significantly (P < 0.05) when the dose of sediment in the medium increased after 20 min at 20°C and 40 min at 15°C (Fig. 4). The 15 and 20°C temperatures were unfavourable for the eggs anyway. It is probable that fertility decreased due to micropyle clogging when the eggs were exposed longer than 10 min to the sediments. It is concluded that presence of sediments in the medium in which the gametes meet does not prevent fertilization.     

Activated sludge treatment of abattoir wastewater—II : Influence of dissolved oxygen concentration

Performance of laboratory scale completely mixed activated sludge reactors fed with abattoir wastewater was measured at different dissolved oxygen (DO) concentrations. Degradation of fat present in the influent was inhibited at DO concentrations below about 0.5 mg l⁻¹, leading to sludges with high fat content which settled poorly due to excessive numbers of filamentous microorganisms. Fat was degraded rapidly at higher DO concentrations (up to 4.0 mg l⁻¹) and the sludge contained few filamentous microorganisms, a low fat content and settled readily. However, effluent quality was highest at low DO concentrations due to lower levels of soluble breakdown products from the fat.When wastewater was fed intermittently at constant aeration rate, sludge with a low fat content and good settleability resulted, even though the DO concentration was about 0.2 mg l⁻¹ for more than 30% of the time. Effluent quality was also high. Thus it is concluded that for full-scale abattoir treatment plants where wastewater flow is intermittent, DO concentration may be low during periods of high loading without adversely affecting effluent quality or sludge settleability.     

Factors affecting the denitrification rate in two water-sediment systems

Effects of temperature, oxygen and nitrate concentrations of the overlying water, and the thickness of the sediment layer on the rate of denitrification in the sediment were investigated in two water-sediment systems, A and B. At 4°C, denitrification started after a prolonged lag period in contrast to nitrification which did not occur significantly. At 15°C, and particularly at 25°C, both processes proceeded readily. The disappearance of NO₂⁻ - N from the overlying water was more rapidly than that of NO₃⁻ - N.The denitrification rate was slightly reduced by increasing the dissolved oxygen concentration in the overlying water from 0 to approximately 2 mgl⁻¹. A further rise of the dissolved oxygen concentration had no further decreasing effect on the denitrification rate.The denitrification rate in sediment was dependent on the nitrate concentration in the overlying water approximating first order kinetics at lower concentrations, gradually becoming independent of the nitrate concentration at higher nitrate contents (zero order kinetics).When starting with a nitrate-nitrogen concentration of 25.2 mgl⁻¹, a sediment layer of 7 mm with A and 14 mm with B was roughly found to be involved in denitrification.Denitrification rates found in the present laboratory experiments were supposed to be considerably lower than those occurring under natural conditions as additional mechanisms for the transport of nitrate into sediments occurred in natural environments.     

Denitrification with a bacterial disc unit

An enclosed rotating disc unit was operated anaerobically as a denitrifying system, with methanol as the hydrogen donor. As the bacterial population became established, denitrification rate increased by 1·5 mg NO₃⁻—N reduced m⁻² h⁻², to a maximum rate of 260 mg NO₃⁻—N reduced m⁻²h⁻¹. The C:N ratio necessary for complete denitrification was found to be 2·6:1. Optimum pH for denitrification lay in the range between pH 7·0 and 8·5. Q₁₀ values were 1·38 between 10 and 30°C, −2·66 above 30°C and 13·06 below 10°C.     

A microbial sensor for BOD

A microbial amperometric sensor for the determination of the biochemical oxygen demand (BOD) determination using Trichosporon cutaneum cells immobilized in polyvinylalcohol has been developed. This sensor allowed BOD measurement with very short response times (< 30 s), an operation stability of 48 days and a serial coefficient of variation of ±3.3% when a sample solution containing 22 mg l⁻¹ BOD was employed. A linear range was obtained up to 100 mg l⁻¹ BOD using a glucose/glutamic acid standard. The sensitivity and specificity was increased by incubation of the BOD sensor with the respective wastewater. Comparable results were obtained for BOD values estimated by the biosensor and those determined by the 5-day method.     

Microbial degradation of nitrilotriacetate (NTA) during river water/groundwater infiltration: Laboratory column studies

In laboratory column experiments with aquifer material collected from a natural river water/groundwater infiltration site, the effects of changes in NTA concentration (0.06–3.40 μM), temperature (5–20°C), and redox conditions on the microbial degradation of NTA during infiltration have been investigated. Under both aerobic and denitrifying conditions, NTA was rapidly mineralized and supported microbial growth as a sole carbon and energy source. The presence of other degradable organic compounds and of trace metals had no significant effect on the total rate of NTA elimination after a 21.8 cm flow distance. At concentrations between 0.02 and 0.05 μM, NTA degradation was still rapid (apparent pseudo first-order rate constants of up to 15 d⁻¹). From the results of the column experiments it may be concluded that under environmental conditions typical for Switzerland, very low residual NTA concentrations (< 0.01 μM) should be present at all times of the year in the groundwater after only a few meters of infiltration, even when concentrations of NTA in river water reach 3–4 μM. This conclusion is corroborated by results of field measurements.     

The effect of temperature on the removal of non-ionic surfactants during small-scale activated-sludge sewage treatment—I. Comparison of alcohol ethoxylates with a branched-chain alkyl phenol ethoxylate

The degree of biodegradability of three non-ionic surfactants has been assessed using small-scale activated-sludge sewage treatment plants. The effect of temperature on biodegradability was studied by operation at 15°, 11° and 8°C.The two alcohol ethoxylate surfactants tested were well degraded at all three operating temperatures. The alkyl phenol ethoxylate surfactant tested was well degraded at 15°C but at lower temperatures the biodegradability was dependent on concentration. At 5 mg 1⁻¹, greater than 90 per cent removal was achieved but at 20 mg 1⁻¹ the degree of removal fluctuated between 40 and 95 per cent at 11°C and between 20 and 80 per cent at 8°C.The present results have been compared with those obtained using the same surfactants in community trials at a small sewage works employing biological filtration. Although a similar temperature effect was observed with the alkyl phenol ethoxylate, the biodegradabilities obtained in the laboratory were consistently greater than those obtained at the sewage works, perhaps because of the constant conditions of the laboratory test.     

Treatment of low strength domestic wastewater using the anaerobic filter

A laboratory scale anaerobic filter packed with synthetic high surface area trickling filter media was used to treat a low strength domestic wastewater averaging 288 mg 1⁻¹ COD. The filter was operated for 60 days after reaching steady-state at 20, 25, 35°C at a loading rate of 0.02 lb COD ft⁻³ day⁻¹ and 24 h hydraulic retention time. Filter effluent BOD₅ averaged 38 mg 1⁻¹ providing an average removal rate of 79%, and effluent COD averaged 78 mg 1⁻¹, corresponding to a 73% removal rate. Removal efficiencies showed very little sensitivity to daily fluctuations in influent wastewater quality. The filter performance at 25 and 35°C was not significantly different, but BOD and TSS removal efficiency declined a: 20°C. Gas production averaged 0.027 ft⁻³ of gas per ft³ of influent wastewater, or 1.875 ft³ of gas per pound of influent COD. Gas composition averaged 30% nitrogen, 65% methane, and 5% carbon dioxide. Ammonia nitrogen and sulfides both increased during treatment. It is concluded that the anaerobic filter is a promising candidate for treatment of low strength wastewaters and that post treatment for sulfides and ammonia may be necessary.     

Lethal toxicity of permethrin (NRDC-143) to rainbow trout, salmo gairdneri, in relation to body weight and water temperature

Lethal toxicity of permethrin varied inversely with water temperature and body weight. The 96 h LC 50 (median lethal concentration) for 1 g trout increased by an order of magnitude from 0.62 to 6.43 μg 1⁻¹ between 5 and 20°C. However between 5 and 10°C the 96 h LC 50 changed little from 0.6 μg 1⁻¹. Large trout (200 g) were considerably more tolerant to permethrin than small fish. Thus, the 96 h LC 50s for 1 and 200 g trout were 3.17 and 314 μg 1⁻¹ respectively at 15°C. The size effect was most pronounced between 1 and 50 g.It is to be noted that the application of permethrin for insect control coincides with the usual period of emergence of rainbow trout fry subsequent to a spawning period of April to late June.     

Impact of climatic fluctuations and land use change on runoff and nutrient losses in rural landscapes

Results on the influence of land use and climatic changes on nutrient losses in the Porijõgi river catchment, south Estonia, are presented. The main tendency in land use changes is a significant increase in abandoned lands (from 1.7% in 1987 to 12.5% in 1994), and a decrease in arable lands (from 41.8 to 22.5%). Significant climatic fluctuations were observed from 1951–1994. Warmer winters (increase from −7.9 to −5.8°C from 1950–1994) and a change in the precipitation pattern have influenced the mean annual water discharge. This results in more intensive material flow during colder seasons and decreased water runoff in summer. Changes in water discharge and land use are also reflected in the mean annual runoff of total inorganic nitrogen (TIN) and total-P which decreased from 15.6 to 2.7 kg N ha⁻¹ yr⁻¹ (83%) and 0.32 to 0.21 kg P ha⁻¹ yr⁻¹ (34%), respectively during this period. However, nutrient losses from the forest subcatchment (upper course) did not change significantly. In contrast, the mean annual runoff of water, organic matter (after biological oxygen demand: BOD₅), TIN, total-P and SO₄ from cultivated subcatchments showed a significant decrease.     

The removal of colour from effluent using various adsorbents—IV. Silica: Equilibria and column studies

The rate of adsorption of Astrazone Blue, a basic dye, on Sorbsil Silica has been studied. The parameters studied include particle size, initial dye concentration, agitation and dye solution temperature. The rate controlling step is mainly intraparticle diffusion, although a small boundary layer resistance is experienced. The activation energy for the adsorption of Astrazone Blue on silica is 13.2 ± 0.6 kJ kg⁻¹. The diffusion coefficients vary from 9 × 10⁻⁹ cm² s⁻¹ at 20°C to 10 × 10⁻⁸ cm² s⁻¹ at 82°C.