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.     

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.     

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.     

Toxicity of chlorine to juvenile spot, Leiostomus Xanthurus

The sensitivity of juvenile spot, Leiostomus xanthurus, to total residual chlorine (TRC) in flowing sea-water was investigated. Incipient LC₅₀ bioassays, histopathology, avoidance tests and the combined effect of thermal stress and TRC were used to assess sensitivity.

Estimated incipient LC₅₀ values were 0.12 mg 1⁻¹ TRC at 10°C and 0.06 mg 1⁻¹ TRC at 15°C. Histological examination of spot used in the incipient LC₅₀ bioassay at 15°C and sacrificed while alive indicated pseudobranch and gill damage occurred in individuals exposed to a measured TRC concentration of 1.57 mg 1⁻¹. Spot exposed to lower concentrations of TRC, 0.02 0.06 mg 1⁻¹ at 15°C and sacrificed alive showed no consistent tissue damage.

Spot demonstrated temperature dependent avoidance responses to TRC. At 10°C, a concentration of 0.18 mg 1⁻¹ was required for significant (X²; P < 0.05) avoidance; at 15 and 20°C, spot showed significant avoidance of TRC concentrations as low as 0.05 mg 1⁻¹.

Simultaneous exposure of spot to thermal stress (5, 10 or 13°C above the acclimation temperature of 15°C) at measured TRC concentrations of 0.05 0.07 and 0.34–0.52 mg 1⁻¹ demonstrated a significant, (Z²) with Yates correction, P < 0.05) increase in sensitivity to TRC with increased temperature and exposure times for some of the groups tested.     

Histological and toxicological responses of the mummichog, Fundulus Heteroclitus (L.) to combinations of levels of cadmium and dissolved oxygen in a freshwater

Impact of dissolved oxygen concentration (D.O.) on toxicity of cadmium to mummichogs in a freshwater medium and histological changes associated with exposure were determined. Levels of mortality were related to duration of exposure, cadmium concentration, and levels of dissolved oxygen. Median tolerance concentrations, at 96h, ranged upward from 1.3 to about 3.0 mg Cd 1⁻¹ at 2.3 and 8.5 mg DO 1⁻¹, respectively. Statistical analyses of mortality data showed factors examined were interdependent and that Cd × DO and Cd × time interactions were significant (P < 0.01). No histopathology was evident at 3 mg Cd 1⁻¹, although histopathology was evident in gills from fish exposed to 28 mg Cd 1⁻¹ for 6 1/2 h.

Responses of mummichogs to cadmium in freshwater are compared with results of a previous study involving exposure of the species to cadmium in seawater and with responses of freshwater fishes subjected to various heavy metals. Differences and similarities in patterns of response are discussed in terms of water balance.     

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.     

Acclimation to and biodegradation of nitrilotriacetate (NTA) at trace concentrations in natural waters

Acclimation to and biodegradation of nitrilotriacetic acid (NTA), an organic builder used in synthetic laundry detergents as the sodium salt, was studied at trace concentrations (ppb) in several river waters. The river waters tested ranged from those where extensive NTA exposure via detergents had not occurred, to those where NTA exposure had been continuous for several years. In rivers not previously exposed to NTA, acclimation and degradation were observed at the lowest initial concentration tested, 5 μg 1⁻¹. Degradation of NTA after acclimation followed apparent first order kinetics, and half lives for NTA removal ranged from 7 to 138 h at initial NTA concentrations of 50 and 5 μg 1⁻¹, respectively. Degradation of NTA in water samples where prior NTA exposure had already occurred required no acclimation and was less variable than in unexposed rivers. First order rate constants varied only slightly over a 1000-fold initial concentration range (1–1000 μg 1⁻¹) and NTA half lives ranged from 7 to 17 h. In general, our results indicate that microflora present in natural waters can acclimate to and degrade NTA, even if exposed to only trace levels in laboratory experiments. However, rates of NTA biodegradation are more rapid and less variable in river waters where natural NTA exposure has already occurred.     

Recovery of ammonia from industrial waste water

Some types of industrial waste water contain high concentration of ammonia, which makes nitrification too costly. It has been found, that ion exchange is an attractive alternative, even the waste water contains such high concentration of competitive ions at 1 g 1⁻¹ Ca²⁺ and 5 g 1⁻¹ Na⁺. However it was found, that the pH increased during the treatment due to the release of OH^- ions left in the interstitial water. Since it is essential for the efficiency that pH is 7·0 or lower, it was necessary to rinse the ion exchangers with acid. The observed data by column experiments agree with the equilibrium data found.     

Mobilization of some metals in water and animal tissue by NTA, EDTA and TPP

Parallel experiments were conducted under stagnant and flowing conditions to determine whether sodium tripolyphosphate (TPP), the conventional detergent builder, or two potential replacements, nitrilotriacetic acid (NTA) and ethylene—diaminetetraacetic acid (EDTA) significantly influenced the mobilization of major cations (Ca, Mg, Na, K) and some heavy metals (Fe, Mn, Zn, Cu, Pb, Cr). Water sediments and tissue of chironomid adults (Chironomus tentans Fabricius), crayfish (Orconectes virilis Hagen) and rainbow trout (Salmo gairdnerii Richardson) were examined. The results showed that the chelating agents applied in concentrations of 0.2–5.0 mg 1⁻¹ often increased the concentration of iron, manganese, lead and zinc in water above contaminated lake sediments. Other heavy metals were not affected significantly. EDTA was the most active mobilizing agent while NTA and TPP both had a less significant effect. The chelating agents generally had little effect on the rate of uptake of most metals by chironomids in aquaria. The role of chelating agents in flowing systems was even less pronounced. Zinc concentrations in water were significantly elevated by the treatment with 1 mg 1⁻¹ EDTA and manganese concentrations were significantly higher in trout from the pond treated with an intermediate level (1 mg 1⁻¹) of NTA. All other treatments yielded levels of major ions and heavy metals that were not significantly different from those in the control ponds.     

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.     

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.     

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.     

Downflow fixed-film anaerobic reactors stability studies under organic and hydraulic overloading at different working volume

Four downflow fixed-film anaerobic reactors were used in this study. The effect of organic and hydraulic overloading on the reactors performance was studied. Initially, the reactors were operated at different working volumes and fed with a synthetic medium during start-up and after reaching a steady organic loading with deproteinized cheese whey. Reactors operated fully flooded (DSFF mode) had higher levels of acetic and butyric acids than reactors operated half flooded (ATF mode) during organic overloading. During hydraulic overloading, propionic and butyric acids rose to much higher levels within DSFF reactors than within ATF reactors. Systems operated in an ATF mode produced slightly higher amounts of methane as well as giving higher conversion at lower HRT than DSFF reactors. ATF reactors had a thin though very active biofilm, since biofilm thickness was controlled by shear and gravity forces as well as fluid recycle. In an ATF, inhibition occurred at a maximum of 2000 mg l⁻¹ of acetic, 3000 mg l⁻¹ of propionic and 400 mg l⁻¹ of butyric acid after a sharp overloading.     

Kinetics of alachlor transformation and identification of metabolites under anaerobic conditions

Alachlor is one of the two most commonly used herbicides in the United States. In the environment, little mineralization of this compound has been found to occur, and metabolites of alachlor may be formed and could accumulate. The objectives of this study were to determine the rate of alachlor biotransformation and to identify the transformation intermediates formed under aqueous denitrifying, methanogenic, and sulfate-reducing conditions. Second-order biotrasnformation coefficients for alachlor were determined to be 7.6 × 10⁻⁵ (±4.0 × 10⁻⁵), 2.9 × 10⁻³ (±1.6 × 10⁻³), and 1.5 × 10⁻² (±1.4 × 10⁻²) 1 mg VSS⁻¹ day⁻¹ under denitrifying, methanogenic, and sulfate-reducing conditions, respectively. Acetyl alachlor and diethyl aniline were positively identified as transformation products of alachlor under all conditions. In denitrifying reactors aniline was identified as a product of alachlor. When acetyl alachlor was fed as the parent compound, aniline was also identified as a transformation product under methanogenic conditions. This research showed that although alachlor is degraded under denitrifying, methanogenic, and sulfate-reducing conditions, significant concentrations of several metabolites are formed and are only slowly degraded.     

Shell valve movement response of dark false mussel, Mytilopsis leucophaeta, to chlorination

Shell valve movements of fouling mussel, Mytilopsis leucophaeta, have been studied in the presence of chlorine, using a mussel monitor. Data showed increasing shell valve closure with increasing chlorine concentration. Shell opening rates of M. leucophaeta at control experiments (0 mg litre⁻¹ residual chlorine) were about 10 times more than those at 1 mg litre⁻¹ residual chlorine. Continuous dosing of 0.75 mg litre⁻¹ residual chlorine is required before shell movements are critically affected. Since current environmental stipulations do not permit this, a level of 0.5 mg litre⁻¹ has to be used continuously during settlement periods of M. leucophaeta for their control. The results also indicate that M. leucophaeta is more tolerant to chlorine than other mussel species.     

Effects of nitrobenzene and zinc on acetate utilizing methanogens

Determination of anaerobic degradation rates and toxic effects of nitrobenzene (NB) on acetate utilizing methanogens was the first objective of this research. Serum bottles were used for anaerobic toxicity assays with an acetate enrichment culture of methanogens. Ten mg/l of nitrobenzene did not inhibit total gas production in the acetate enrichment methanogenic culture. Twenty and thirty mg/l of nitrobenzene caused reversible inhibition of methanogenesis. Batch kinetic experiments showed that 20 mg/l of nitrobenzene was degraded with a first-order rate constant, k, of 0.37 d⁻¹. Acetate was not degraded during the first 7 days when the measured nitrobenzene concentration was higher than about 1 mg/l. The second objective was to determine the effect of zinc on nitrobenzene degradation in methanogenic systems. Ten mg/l of spiked zinc caused a reduction of gas production in the systems with 10 mg/l of nitrobenzene; 20 mg/l of zinc led to failures of systems with 10 and 20 mg/l of nitrobenzene. With 10 and 20 mg/l of added zinc, the k value for nitrobenzene degradation decreased to 0.18 d⁻¹ and 0.14 d⁻¹, respectively. With 20 mg/l of Zn, acetate was not degraded at all even after nitrobenzene concentration reached 0.1 mg/l, indicating toxicity of Zn to methanogenesis. Abiotic control tests with autoclaved culture showed that adsorption alone could remove 60–70% of spiked nitrobenzene in 36 days. However, the samples extracted from solids in the methanogenic test systems showed that nitrobenzene was below the detection limit of 0.1 mg/l, indicating biodegradation of nitrobenzene in these systems. Traces of benzene were seen as an intermediate in the liquid samples. Headspace analysis showed that nitrobenzene and benzene were below detection limits.     

Mechanisms and products of ozonolysis of aniline in aqueous solution containing nitrite ion

The presence of nitrite ions (1 × 10⁻⁴ M) in the reaction medium affected the aqueous reaction of aniline (1 × 10⁻⁴ M) and ozone (2.07–2.15 × 10⁻⁴ M) at pH 6.25–10.65; o-, m- and p-nitroaniline were formed in addition to reaction products reported earlier. The combined yield of o- and p-nitroaniline was as high as 8%. Their yields were significantly higher at pH 6.25 and 7.25 than at pH 10.65 and carbonate species-inhibited their formation. The reaction mechanisms for the formation of the nitroanilines involves pernitrous acid, hydroxyl radical and nitrogen dioxide radical as the important intermediates.     

Utilisation de l''algue oocystis sp. pour le traitement tertiaire des eaux usées—I. Culture en vrac de cellules préalablement conditionnées en cyclostat

With the aim of developing an efficient and economic method for the tertiary treatment of wastewater, a two-phased culture system of Oocystis alga is presented. During the first phase, a unialgal strain grows in a cyclostat supplied with secondary effluents diluted to a low concentration (50 μM NH₄⁺, i.e. 0.7 mg N 1⁻¹) of inorganic ions. Once the equilibrium is reached (i.e. the cell population is conditioned and the nutrient concentration is zero), in a second phase, the starved cells are mixed with a secondary effluent which has a higher nutrient content (200–400 μM NH₄⁺, i.e., 2.8–5.6 mg N 1⁻¹). Ion depletion (NH₄⁺, NO₃^-, NO₂^- and PO₄^3-) follows specific kinetics; successive identifiable stages related to photoperiod lead to a complete stripping of nutrients. In addition to ion concentrations, pH and cell population were determined every 2 h during the experiment. Results and conclusions are presented.     

Growth of Selenastrum capricornutum in natural waters augmented with detergent products in wastewaters

A determination of whether the removal of phosphate builders from detergents would modify the ability of domestic secondary treated sewage effluent to stimulate the growth of a test alga (Selenastrum capricornutum-Printz) in receiving waters alone and augmented with detergent products was made. The lakes used as sources of test waters were located in northeastern New York State and possessed total phosphorus concentrations ranging from ca. 0.01 to 0.04 mg P1⁻¹.

The alga experienced stimulation in all three test lake waters from secondary sewage containing detergent with phosphate or detergent without phosphate. A concentration of 60 μg P 1⁻¹ was sufficient to effect significant algal growth in two of the test waters; however, concentrations ranging up to 110 μg P 1⁻¹ did not generate such a response in the third test water. This latter result and others suggested that neither phosphorus nor other nutrients from these wastewater additions were the factors fully accountable for the observed response(s).