Fish toxicity of jet fuels—I. The toxicity of the synthetic fuel JP-9 and its components

The toxicity of the jet fuel JP-9 and its components RJ-4, RJ-5 and MCH was assessed in static bioassays on the warm water fish, golden shiner (Notemigonus chrysoleucas). The 96-h LC₅₀ of emulsions was 2.0 mg 1⁻¹ for JP-9, 0.51 mg 1⁻¹ for RJ-4, 0.61 mg 1⁻¹ for RJ-5 and 72 mg 1⁻¹ for MCH. As determined by the 96-h LC₅₀ values unemulsified fuel (pools of fuel) JP-9 was 235 times less toxic, RJ-4 was 196 times less toxic, RJ-5 was 7700 times less toxic and MCH was 3.3 times less toxic than the corresponding emulsified materials.

In continuous flow bioassays with the water soluble fraction of the fuel and its components the effect on egg hatchability and fry development of flagfish (Jordanella floridae) and rainbow trout (Salmo gairdneri) was studied. The no effect of level on flagfish egg hatchability was 0.23 mg 1⁻¹ for JP-9 and 0.05 mg 1⁻¹ for RJ-5. Concentrations of 0.83 mg 1⁻¹ MCH and 0.2 mg 1⁻¹ RJ-4 did not affect egg hatchability. In rainbow trout studies 97-day LC₅₀ values for RJ-4 and RJ-5 were 0.045 mg 1⁻¹ and 0.072 mg 1⁻¹, respectively, and 23-day LC₅₀ values for JP-9 and MCH were 0.26 mg 1⁻¹ and 1.3 mg 1⁻¹, respectively.

The accumulation of fuels in fish bodies was studied and it was found that flagfish can tolerate a total body burden of 0.5 mg MCH g⁻¹ wet weight without lethality. It was also found that body burdens of 0.43 mg RJ-4 g⁻¹ and of 0.27 mg RJ-5 g⁻¹ on a wet weight basis will produce 50% mortality in rainbow trout.

Voiding of MCH from fish bodies occurs readily in fuel-free water, but RJ-4 and RJ-5 are retained in the tissues.     

Toxicities of total and chelex-labile cadmium to salmon in solutions of natural water and diluted sewage with potentially different cadmium complexing capacities

The LC₅₀ for total Cd averaged 4.8 and 8.0 μg1⁻¹ in river water and 33% sewage-treatment-plant effluent (STPE), respectively, and for Chelex-labile Cd, 3.9 and 5.6 μg1⁻¹, respectively. The LC₅₀ values for total Cd were significantly (P < 0.05) different, indicating a reduction in toxicity of Cd in the presence of 33% STPE, presumably due to complexation of Cd²⁺. The similarity of LC₅₀ values for Chelex-labile Cd indicates that that fraction contained toxic species of Cd at approximately the same concentration(s) in both river water and 33% STPE; it is therefore considered a better measure of Cd toxicity than total Cd. Furthermore, mortality was correlated with the concentration of Chelex-labile Cd but not with that of Chelex-nonlabile Cd. Measurements of Cd²⁺-complexing capacity by the Chelex method indicated that toxicity was due, at least in part, to Cd²⁺. Values were less than those obtained by the ion-selective-electrode method; these indicated that toxicity was due only to complexed Cd. Values from both methods were uncorrelated with LC₅₀ values.     

Effect of exposure time and copper concentration on reproduction of the fathead minnow (Pimephales Promelas)

Three concurrent studies were conducted to determine the chronic effect of prespawning exposure to various concentrations of copper on fathead minnow reproduction. Copper was introduced into the three exposure systems to give 6-, 3-, and 0-months exposure prior to spawning. Prespawning exposure time had no significant effect on reproduction. Number of eggs produced per female decreased, however, with increase in copper concentrations. Egg production at copper concentrations of 37μg 1⁻¹ and higher was significantly lower (P = 0.05) than in the control, but at concentrations of 24μg 1⁻¹ and lower it was not different. The maximum acceptable toxicant concentration (MATC) was estimated to be 32μg Cu 1⁻¹, which is 0.07 of the 96h LC₅₀. This application factor for copper is similar to those found in other studies.     

Aerobic treatment of piggery waste

The operating characteristics of laboratory waste treatment systems were studied during the aerobic degradation of pig excrement at different loading rates and temperatures. The treatment systems were of two types: one was operated with floc formation and gravity separation of liquid and suspended solid effluents; and a second was operated without floc formation or separation of the effluent into liquid and solid fractions.

With an operating temperature of 15°C the parameters most affected by loading rate were (1) the concentrations of suspended solids and chemical oxygen demand in the liquid effluent; (2) the pH value of the mixed liquor; (3) nitrification; (4) the BOD of the supernatant from the mixed liquor; and (5) output of suspended solids as a percentage of input.

The concentrations of suspended solids and chemical oxygen demand in the liquid effluents were little affected by loading rates in the range 0·05-0·15 g SS g MLSS⁻¹ d⁻¹ (0·02-0·06 g BOD g MLSS⁻¹ d⁻¹) but increased with increasing loading rate in the range 0·15-0·30 (0·06-0·12 BOD). At loading rates below about 0·17 g SS g MLSS⁻¹ d⁻¹ (0·07 g BOD g MLSS⁻¹ d⁻¹) the mixed liquors were acidic, with pH values down to 5·2, whereas at loading rates above about 0·80 (0·32 BOD) they were alkaline, with pH values up to 8·9. At intermediate loading rates the mixed liquor pH value was more variable though in general the higher the loading rate the higher also the pH value of the mixed liquor. Acidic conditions in the mixed liquors were attributed to the occurrence of nitrification, while in the absence of nitrification the mixed liquors remained alkaline. The concentration of BOD₅ in the supernatant from the mixed liquors increased with increasing loading rate from about 35 mg 1⁻¹ at a loading rate of 0·17 g SS g MLSS⁻¹ d⁻¹ (0·07 g BOD g MLSS⁻¹ d⁻¹) to about 250 mg 1⁻¹ at a loading rate of 1·30 (0·52 BOD). The output of suspended solids from the treatment systems represented about 70 per cent of input suspended solids at loading rates of about 0·15 g SS g MLSS⁻¹ d⁻¹ (0·06 g BOD g MLSS⁻¹ d⁻¹) and increased to about 100 per cent at loading rates of 0·80 (0·32 BOD). Output of chemical oxygen demand was about 60 per cent of input at the lower loading rates and 80–90 per cent at the higher ones.

Operation of treatment units at temperatures of 5 and 10°C instead of 15°C had little effect on the efficiency of degradation at loading rates in the range 0·085-0·20 g SS g MLSS⁻¹ d⁻¹ (0·034-0·08 g BOD g MLSS⁻¹ d⁻¹), but nitrification was prevented at 5°C. At loading rates of 0·77 (0·31 BOD) and 1·46 (0·58 BOD) operation at 25°C appeared to increase the amount of degradation as compared with that achieved at 15°C.

The practical implications of the results and possible future approaches to the aerobic treatment of farm wastes are discussed.     

Complexation of copper in the effluent of a sewage treatment plant and an estimate of its influence on toxicity to coho salmon

Measurements by cupric ion electrode of the complexing capacity of the effluent from a sewage treatment plant (STPE) averaged 0.300 mg 1⁻¹. Of the complexed Cu 67% was due to compounds of 10,000 MW. Organic compounds removable by activated carbon composed 88% of the total organic carbon and were responsible for 87% of the complexation. Complexation of Cu²⁺ by STPE diminishes the toxicity from total Cu to juvenile coho salmon; the LC₅₀ was 0.164 mg 1⁻¹ for river water vs 0.286 mg 1⁻¹ for 40% STPE. The LC₅₀ of Cu²⁺ was approximately the same (0.017 vs 0.022 mg 1⁻¹) in both matrices; this species thus appears to play a toxic role. The mean survival time in diluted STPE with added Cu was inversely proportional to the Cu²⁺ concentration.     

Effect of water hardness on the toxicity of cadmium to micro-organisms

A study was made of the effect of water hardness at different concentrations (viz. 0, 80, 120, 160, 240, 320, 400 and 480 mg l⁻¹ as CaCO₃) on the toxicity of cadmium metal (5 mg 1⁻¹) as sulphate to saprophytic and nitrifying bacteria, with respect to the rate constant (K) and ultimate biochemical oxygen demand (L) which were calculated from BOD data (15 days) using the Thomas Graphical Method. Glucose was used as a source of carbon for micro-organisms. It was observed that the toxicity of cadmium to micro-organisms (both saprophytic and nitrifying) decreased with increasing hardness and reached a maximum at 320 mg 1⁻¹ as CaCO₃ for nitrifying and 400 mg l⁻¹ as CaCO₃ for saprophytic bacteria. After these hardness levels, the ultimate BOD (L) and rate constant (K) showed a decrease. Nitrifying bacteria were found to be more sensitive to the metal as well as to its complexation with calcium or with other ions as they retained their normal activity at a lower hardness level as compared to saprophytic bacteria.     

The effects of free chlorine and chloramine on growth and respiration rates of larval lobsters (Homarus Americanus)

The length, dry weight and standard respiration rate of larval lobsters (Homarus americanus) were monitored for 19 days following a 60 min exposure at 25°C to 1.0 mg I⁻¹ applied free chlorine and 1.0 mg I⁻¹ applied chloramine. Compared to control organisms, significantly lower increases in dry weight (P < 0.05) and significant reductions in standard respiration rates (P < 0.01) were measured among exposed organisms; greater differences were detected among chloramine exposed organisms. From these results it can be concluded that acute exposure to either free chlorine or chloramine results in subsequent reductions in growth and metabolic activity of larval lobsters.     

Denitrification rates in relation to stream sediment characteristics

Potential rates of nitrate removal were studied in sediments from three Ontario rivers that differed in texture, organic carbon contents and other characteristics. Intact 0–5 cm depth sediment cores from 22 sites on each river were overlain with aerated 5 mg 1⁻¹ NO₃⁻-N solution and incubated in the laboratory at 21°C for 48 h. Rates of nitrate-N loss from the overlying solutions varied from 37 to 412 mg m⁻² day⁻¹ for a 24 h incubation period. The acetylene blockage technique was used with nitrate amended sediments to evaluate the relative importance of denitrification and nitrate reduction to ammonium. Denitrification accounted for 80–100% of the nitrate loss in the majority of sediment samples tested. Rates of nitrate loss for the 24 h period exhibited a highly significant positive correlation (r = 0.82–0.89) with the water-soluble carbon content of the sediments in each river. Significant relationships were also observed between nitrate loss and organic carbon, total nitrogen and sediment ammonium. A decline in nitrate loss via denitrification and increased nitrate reduction to ammonium was correlated with the organic carbon and water-soluble carbon content of the stream sediments.     

Anaerobic biological treatment of phenol at 9.5-15 degrees C in an expanded granular sludge bed (EGSB)-based bioreactor

The aims of this study were to demonstrate the (1) feasibility of psychrophilic, or low-temperature, anaerobic digestion (PAD) of phenolic wastewaters at 10–15 °C; (2) economic attractiveness of PAD for the treatment of phenol as measured by daily biogas yields and (3) impact on bioreactor performance of phenol loading rates (PLRs) in excess of those previously documented (1.2 kg phenol m⁻³ d⁻¹). Two expanded granular sludge bed (EGSB)-based bioreactors, R1 and R2, were employed to mineralise a volatile fatty acid-based wastewater. R2 influent wastewater was supplemented with phenol at an initial concentration of 500 mg l⁻¹ (PLR, 1 kg m⁻³ d⁻¹). Reactor performance was measured by chemical oxygen demand (COD) removal efficiency, CH₄ composition of biogas and phenol removal (R2 only). Specific methanogenic activity, biodegradability and toxicity assays were employed to monitor the physiological capacity of reactor biomass samples. The applied PLR was increased to 2 kg m⁻³ d⁻¹ on day 147 and phenol removal by day 415 was 99% efficient, with 4 mg l⁻¹ present in R2 effluent. The operational temperature of R1 (control) and R2 was reduced by stepwise decrements from 15 °C through to a final operating temperature of 9.5 °C. COD removal efficiencies of c. 90% were recorded in both bioreactors at the conclusion of the trial (day 673), when the phenol concentration in R2 effluent was below 30 mg l⁻¹. Daily biogas yields were determined during the final (9.5 °C) operating period, when typical daily R2 CH₄ yields of c. 3.3 l CH₄ g⁻¹ COD_removed d⁻¹ were recorded. The rate of phenol depletion and methanation by R2 biomass by day 673 were 68 mg phenol g VSS⁻¹ d⁻¹ and 12–20 ml CH₄ g VSS⁻¹ d⁻¹, respectively.     

Microbial uptake of cadmium and its effects on the biochemical oxygen demand at various temperatures

Uptake of cadmium by microbes at different temperatures has been studied at pH 7. Glycine was used as a source of carbon for microorganisms in the BOD bottle at 20, 30, 40 and 50°C with varying concentrations of cadmium: control 0.0437, 0.437, 0.875 and 1.31 mg 1⁻¹ in each set. The influence of temperatures on the toxic effects of cadmium has been studied with respect to rate constant (k) and ultimate biochemical oxygen demand which were calculated from BOD data using Thomas Graphical method. Consumed cadmium mg 1⁻¹ was determined after eight days and it varied from 14.04 to 32.40% at four temperatures. Highest consumption of Cd was noted in the set at 30 and 40°C and lowest at 50°C.     

Combined γ-ray irradiation-activated sludge treatment of humic acid solution from landfill leachate

Humic acid, which is a typical microbially refractory organic substance, was extracted from a landfill leachate. The humic acid solution (COD = 367 mg 1⁻¹; TOC = 293 mg 1⁻¹; BOD = 27 mg 1⁻¹) was applied to a batch scale activated sludge treatment after the modification of its biodegradability by γ-ray irradiation. The BOD increased to 64 mg 1⁻¹ by irradiation of 15 kGy (1.5 Mrad), while the COD and TOC decreased to 231 and 230 mg 1⁻¹, respectively. When the irradiated sample was treated with an activated sludge, the BOD decreased rapidly in 2–3 h to about 15 mg 1⁻¹ which was a similar value as the unirradiated sample was treated. The elimination efficiency of TOC by the sludge treatment was approximately equal to that obtained by irradiation of 15 kGy. These facts suggest a utility of applying microbial processes after radiation treatment of microbially refractory wastewaters.     

Hypolimnetic aeration and dissolved gas concentrations: Enclosure experiments

Two large circular enclosures, each containing approx. 550 m³ of water, 14 m deep, and open to the mud-water interface, were used to monitor the effects of hypolimnetic aeration. One enclosure was held as a control, the other aerated every 3 or 4 days for a period long enough (usually < 2 h) to maintain hypolimnetic O₂ levels at > 4 mg 1⁻¹. Nutrient additions (10 g of 90% H₃ PO₄ and 250 g NaNO₃ per week) to each enclosure were controlled from the commencement of the experiment (17 June 1980) until its completion (2 November 1981). Temperatures in both enclosures were identical. Hypolimnetic O₂ levels in the control fell to zero during both summers, but remained at > 4 mg 1⁻¹ in the aerated enclosure. Free N₂ concentrations in the hypolimnion of the aerated enclosure was higher than in the control. Concentrations of H₂S in the control hypolimnion increased to > 5 mg 1⁻¹ and concentrations of CH₄ increased to > 18 mg 1⁻¹. Both remained at or near zero in the aerated enclosure. Tests of aerator efficiency suggested that the full air-lift design that was employed had an average O₂ exchange efficiency of 42% which is higher than the values reported for most other designs.     

Plant-scale phosphate removal experiments at the Balatonfüred sewage treatment plant

Operational parameters at the Balatonfüred sewage treatment plant and the technology of chemical phosphate removal on a plant-scale have been examined in a 3-week series of experiments. Aluminium sulphate and iron(II) sulphate have been used as precipitating agents. It was found that the addition of 30 mg 1⁻¹ aluminium gave 90 per cent removal of total phosphorus. The addition of 60 mg 1⁻¹ iron(II) gave 89 per cent removal of total phosphorus. The costs of these chemicals are 0·93 Ft m⁻³ for aluminium and 0·11 Ft m⁻³ for iron precipitants, resp. Thus the iron is significantly less expensive as a phosphorus precipitant.     

Degradation of acetic and propionic acids in the methane fermentation

A series of batch digestion experiments was performed to evaluate the effect of elevated acetic acid concentrations on the degradation of propionic acid and vice versa. Flask digesters were incubated at 37°C with acetic and propionic acids added at up to 2000 and 1500 mg 1⁻¹, respectively. It was found that increasing the concentration of either acid from low levels reduced the rate of its utilization and that increasing the acetic acid concentration from 1000 to 2000 mg 1⁻¹ significantly inhibited degradation of propionic acid added at 500 mg 1⁻¹. Good agreement was obtained from fitting the logistic equation to the measured data and between duplicate runs performed within the experiments. The observed inhibition of propionate degradation by acetate confirms several earlier reports of product inhibition in the literature and emphasizes the importance of controlling acid levels in maintaining satisfactory digester operation.     

Empirical rate equation for trihalomethane formation with chlorination of humic substances in water

Trihalomethane (THM) in drinking water is formed by chlorination of humic substances. In this study, the rates of THM formation in aqueous solution of humic acid were examined under various conditions. The following rate equation was obtained empirically. [THM] = k (pH − a)[TOC][Cl₂]₀^mtⁿ.

Here, [THM] is the concentration of total THM after t h, [TOC] and [Cl₂]₀ are the concentrations of total organic carbon and chlorine dose, k is the rate constant and a, m and n are parameters. The values of k, a, m and n for humic acid as reagent were obtained as 8.2 × 10⁻⁴ (l^mmg^−mh⁻ⁿ), 2.8, 0.25 and 0.36, respectively. The activation energy was obtained as 37 kJ mol⁻¹. Further, it was proved that the above equation could be applied to the rates of THM formation from precursors in actual river and lake waters.     

Studies on marine biological filters: Model filters

Model systems of 401. capacity were used to study chemical changes which affected buffering in continuously recycled sea water and which restricted nitrification in percolating biological filters at 28°C.

Sustained hydrogen ion production during the microbial oxidation of ammonia to nitrite caused continuous carbon dioxide formation from carbonate and bicarbonate. The carbon dioxide was steadily lost to the air through vigorous aeration, leaving < 2 mg inorganic carbon 1⁻¹ in the sea water. Oxidation of nitrate to nitrate did not significantly reduce pH nor deplete buffer capacity.

Ammonia oxidation was severely inhibited by the combination of low pH and dissolved inorganic carbon levels, but similar low levels of pH produced when carbon dioxide was bubbled through the water had only a moderate effect. Inhibition could be rapidly overcome or prevented by additions of inorganic carbon, sodium hydroxide or sodium dihydrogen phosphate.

Values recorded for the maximum specific growth rate of Nitrosomonas and Nitrobacter were 0.53 and 0.81 d⁻¹ respectively. The corresponding generation or doubling times were calculated to be 31.4 and 20.5 h.

Some evidence was found for the uptake of phosphate and the formation of hydroxylamine during nitrification.     

Sorption of cadmium(II) and zinc(II) ions from aqueous solutions by cassava waste biomass (Manihot sculenta Cranz)

The sorption of two divalent metal ions, Cd(II) and Zn(II), onto untreated and differentially acid-treated cassava waste biomass over a wide range of reaction conditions was studied at 30°C. The metal ion removal from the spent biomass was also measured. The batch experiments show that pH 4.5–5.5 was the best range for the sorption of the metal ions for untreated and acid-treated biomass. Time-dependent experiments for the metal ions showed that for the two metals examined, binding to the cassava waste biomass was rapid and occurred within 30 min and completed within 1 h. High sorption capacities were observed for the two metals. The binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 86.68 mg/g Cd, 55.82 mg/g Zn and 647.48 mg/g Cd, 559.74 mg/g Zn for untreated and acid-treated biomass, respectively. It was further found that the rate of sorption was particle-diffusion controlled, and the sorption rate coefficients were determined to be 2.30×10⁻¹ min⁻¹ (Cd²⁺), 4.0×10⁻³ min⁻¹ (Zn²⁺) and 1.09×10⁻¹ min⁻¹ (Cd²⁺), 3.67×10⁻² min⁻¹ (Zn²⁺) for 0.5 and 1.00 M differential acid treatment, respectively. Desorption studies showed that acid treatment inhibited effective recovery of metal ions already bound to the biomass as a result of stronger sulfhydryl-metal bonds formed. Less than 25% of both metals were desorbed as concentration of acid treating reagent increases. However, over 60% Cd and 40% Zn were recovered from untreated biomass during the desorption study. The results from these studies indicated that both untreated and acid-treated cassava waste biomass could be employed in the removal of toxic and valuable metals from industrial effluents.     

Influence of inter-annual variations in climatic factors on fecal coliform levels in Mississippi Sound

Information on the effects of inter-annual variations in climatic factors on fecal coliform levels in coastal waters is scarce. We used 11 years (1990–2001) of rainfall, water temperature, Pearl River stage and salinity data to assess the effects of the 1991–1992 and 1997–1998 El Niño events on fecal coliform levels in Mississippi Sound. El Niño-Southern Oscillation had major effects on Pearl River stage and water quality in the Sound. The geometric mean fecal coliform number differed among years (P=0.0001), being highest during 1991–1992 El Niño years (14.22 MPN per 100 ml) and lowest during 1999–2000 La Niña years (<1.8 MPN per 100 ml). Mean salinity varied among years (P=0.0001) from 9 ppt (1991–1992) to 21 ppt (1999–2000). Mean water temperature was lowest in 1997–1998 (14.5 °C) and highest in 1998–2000 (19.4 °C). Pearl River stage differed among years (P=0.0001), ranging from 1.96 m (1999–2000) to 3.57 m (1997–1998). Inverse relationships were observed between fecal coliform levels and salinity (r²=0.74; P=0.001) and water temperature (r²=0.69; P=0.001), whereas positive relationships were obtained with total rainfall (r²=0.52; P=0.013) and Pearl River stage (r²=0.90; P=0.0001). These relationships are useful for evaluating the potential effects of climate change on water quality and classification of shellfish growing waters in order to protect humans from consuming contaminated shellfish in shallow river-influenced estuaries.     

Field evaluation of geonet flow rate (transmissivity) under increasing load

This paper presents data from a full scale field test of a geonet placed between two geomembranes used as a leak detection system for a solid waste landfill. The cell under investigation is 1·54 ha in area, with the geonet covering 0·87 ha of the base of the cell. The remaining sideslope area was also covered by geonet, but did not contribute to the flow rate testing. Approximately 2300 liters of water were injected at three different times; i.e., at landfill waste heights corresponding to 12, 153 and 311 kPa normal stresses. The percentages of recovered water within a 15-h period were 93·9%, 89·6% and 81·2% respectively. The calculated transmissivity values reflected the increased normal stress as would have been anticipated, i.e., transmissivity values decreased from 45·2 to 43·5 to 40·0 × 10⁻⁴ m²/s, respectively. These decreases were anticipated due to the elastic intrusion of the geomembranes into the geonet under the gradually increasing normal stresses. The results indicate that geonets are viable drainage materials under actual full-scale field conditions and should certainly be considered as drainage replacements for natural granular soil drainage media.     

Denitrification with methanol in tertiary filtration

The large wastewater treatment plants in Switzerland have to be extended by enhanced nitrogen removal to comply with the relevant EU directives. Denitrification in tertiary filtration is a cost-effective alternative to extended denitrification in an activated sludge system which needs additional reactor volume. Full-scale experiments in denitrification with methanol in tertiary filtration were performed at the wastewater treatment plant in Zurich-Werdhölzli during a summer and a winter campaign, each lasting 4 months. One of the original 22-filter cells was equipped with a methanol dosage unit for this purpose. Denitrification rates of about 1.0 kg-N m⁻³ d⁻¹ are attained at temperatures of 12–15°C. The denitrification is reduced significantly after main back-washing. Frequent back-washings (several times per day) lead to methanol breakthroughs due to biofilm loss. The yield coefficient Y_COD was 0.4 kg-COD_xkg-COD⁻¹_me. In spite of the methanol dosage, the quality of the filter effluent is very good during normal operation in the winter campaign. Accumulation of the nitrite intermediate product was observed in summer at temperatures of 20–22°C.