Automated fluorometric method for determination of boron in waters, detergents and sewage effluents

An automated method for the determination of boron in natural waters, detergents and sewage effluents is described. The method is based on the reaction of 4'-chloro-2-hydroxy-4-methoxybenzophenone (CHMB) with boron to produce fluorescent species, in a 90% sulfuric acid medium. The method has been made specific to remove any interferences from all major and minor ions and other organic compounds normally present in water. The method is capable of measuring different chemical forms of boron such as boric acid, borax, sodium perborate and tetraphenyl boron. The method analyses 10 samples per hour, in the 5–100 μg 1⁻¹ boron range. The rate of sample analysis can be increased to 20 per hour at higher concentration ranges. The limit of detection is 1 μg 1⁻¹ boron.     

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).     

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.     

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.     

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.     

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.     

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.     

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.     

Removal of saxitoxins from drinking water by granular activated carbon, ozone and hydrogen peroxide--implications for compliance with the Australian drinking water guidelines

In a laboratory-scale trial, we studied the removal of saxitoxins from water by ozone, granular activated carbon (GAC) and H₂O₂, and considered the implications of residual toxicity for compliance with the Australian drinking water standards. Cell-free extracts of Anabaena circinalis were added to raw, untreated drinking water obtained from a water supply reservoir to provide a toxicity of 30 μg (STX equivalents) l⁻¹. Ozone alone, or in combination with H₂O₂, failed to destroy the highly toxic STX and GTX-2/3, and only partially destroyed dc-STX, and the low-toxicity C-toxins and GTX-5. In all cases, the toxicity of the water was reduced by less than 10%. GAC removed all of the STX, dc-STX and GTXs, but only partially removed the C-toxins. However, the residual toxicity was reduced to the suggested Australian drinking water guideline concentration of 3 μg (STX equivalents) l⁻¹ without O₃ pre-treatment. Modelling the spontaneous chemical degradation of residual C-toxins following treatment shows that residual toxicity could increase to 10 μg l⁻¹ after 11 d due to formation of dc-GTXs and would then gradually decay. In all, residual toxicity would exceed the Australian drinking water guideline concentration for a total of 50 d.     

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.     

Atrazine in groundwater of Vojvodina Province

The objective of this study was to investigate concentrations of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), deethylatrazine (DEA) (2-amino-4-chloro-6-isopropylamino-1,3,5-triazine), deisopropylatrazine (DIA) (2-amino-4-chloro-6-ethylamino-1,3,5-triazine) and deethyldeisopropylatrazine (DEIA) (6-chloro-2,4-diamino-1,3,5-triazine) in groundwaters of Vojvodina Province. A study was conducted during April 2001. Some 110 samples of groundwater were taken from near surface aquifers. The water samples were first passed through a disk containing solid matrix coated with a chemically bonded C-18 organic phase. The disk was then eluted with supercritical carbon dioxide to remove compounds from the sorbent. Finally the extract was injected into capillary gas chromatograph. Average concentrations were 0.198 μg L⁻¹ for atrazine, 0.116 μg L⁻¹ for DEA, 0.043 μg L⁻¹ for DIA and 0.077 μg L⁻¹ for DEIA.     

Solubility of polychlorinated biphenyls and capacitor fluid in water

A quantitative method to determine the solubility of polychlorinated biphenyls (PCBs) and used capacitor fluid in water was developed employing high-resolution glass capillary-column gas chromatography. The responses of the electron capture detector to mono-, di-, tri- and tetra-chlorobiphenyls and an internal standard were used to estimate the solubility of the PCBs. Results of the rate of dissolution of Aroclor 1242 and used capacitor fluid in water indicated that a period of five months was required to reach equilibrium. The water-solubile fractions of Aroclor 1242 and used capacitor fluid (Aroclor 1242-impregnated) were found to be identical. Certain isomers of the mono-, di- and poly-biphenyls in Aroclor 1242 were relatively soluble and were identified as 2-mono-, 2,4′-di-, 2,5.2′-tri-, 2.3,2′-tri-, 2,5.4′-tri-, 2,5.2′,5′-tetra-, 2,4.2′,5′-tetra-, 2,4.2′,4′-tetra-, 2,3.2′,5′-tetra- and 2,4.3′,4′-tetra-chlorobiphenyl. In general, the water-soluble fractions of the PCB mixtures were richer in the lower chlorinated isomers than the original PCB mixtures. The solubilities of Aroclor 1016, 1221, 1242, and 1254 were 906. 3516, 703 and 70μg1⁻¹, respectively, whereas the solubility of the used capacitor fluid was the same as that of Aroclor 1242.     

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.     

On the reoxygenation efficiency of diffused air aeration

One technique used to increase the dissolved oxygen concentration of polluted waters is the bubbling of air through a diffuser pipe located at depth, thereby producing a bubble curtain from which oxygen transfer to the water occurs.

The results of laboratory studies on the aeration efficiency of a diffuser placed along the entire width of a flume, perpendicular to a cross flow are presented (two dimensional aeration). Parameters investigated include (1) diffuser type-porous materials with mean pore sizes of 40, 90 and 180 μm and perforated pipes with 0.4, 0.6 and 1.0 mm diameter ports (2) air flow rate per unit width 3–53 m³ (m h)⁻¹ and (3) cross flow velocity (2.5–15 cm s⁻¹. The effect of variation from the two dimensional situation is also discussed as well as the consequence of using oxygen instead of air, and the sensitivity to discharge angle, port spacing and the free surface. The measured efficiencies are compared with theory as well as available laboratory and field data.

The major conclusions are (1) aeration efficiencies using diffused air aeration are on the order of 2–13%m⁻¹ (2) the aeration efficiency increases with increasing cross flow velocity and decreasing air flow rate per unit width (3) aeration efficiencies using porous filters, for air flow rates less than 40 m³ (m h)⁻¹, are significantly higher (a factor of 2–3) than those achieved using perforated pipes (4) changing the pore size from 40 to 180 μm, the port size from 0.4 to 1.0 mm or the port spacing does not significantly effect the aeration efficiency (5) aeration using oxygen is somewhat less efficient than that using air. However, since equivalent oxygen bubbles contain approximately five times more oxygen than air bubbles, more oxygen is transferred on an absolute basis at the same gas flow rate using compressed oxygen as opposed to air (6) aeration efficiency resulting from aeration over a portion of the entire width can be reasonably predicted using the results of the two dimensional studies and (7) the available laboratory and field data compare well with the results of these laboratory studies.     

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.     

Removal of As(III) and As(V) from water using a natural Fe and Mn enriched sample

The arsenic removal capacity of a natural oxide sample consisting basically of Mn-minerals (birnessite, cryptomelane, todorokite), and Fe-oxides (goethite, hematite), collected in the Iron Quadrangle mineral province in Minas Gerais, Brazil, has been investigated. As-spiked tap water and an As-rich mining effluent with As-concentrations from 100 μg L⁻¹ to 100 mg L⁻¹ were used for the experiments. Sorbent fractions of different particle sizes (<38 μm to 0.5 mm), including spherical material (diameter 2 mm), have been used. Batch and column experiments (pH values of 3.0, 5.5, and 8.5 for batch, and about pH 7.0 for column) demonstrated the high adsorption capacity of the material, with the sorption of As(III) being higher than that of As(V). At pH 3.0, the maximum uptake for As(V) and for As(III)-treated materials were 8.5 and 14.7 mg g⁻¹, respectively. The Mn-minerals promoted the oxidation of As(III) to As(V), for both sorbed and dissolved As-species. Column experiments with the cFeMn-c sample for an initial As-concentration of 100 μg L⁻¹ demonstrated a very efficient elimination of As(III), since the drinking water limit of 10 μg L⁻¹ was exceeded only after 7400 BV total throughput. The As-release from the loaded samples was below the limit established by the toxicity characteristic leaching procedure, thus making the spent material suitable for discharge in landfill deposits.     

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.     

A planktonic Oscillatoria species from Mississippi catfish ponds that produces the off-flavor compound 2-methylisoborneol

A planktonic, gas-vacuolate Oscillatoria species was isolated from catfish ponds in Mississippi during an episode of off-flavor and high 2-methylisoborneol (MIB) levels. Volatile compounds from unialgal cultures were isolated using closed-loop stripping, liquid-liquid extraction, and analyzed by gas chromatography and mass spectroscopy. The organism produced MIB at 75–87 μg 1⁻¹ after 2–3 wk of incubation at 25°C. The alga was found in moderate to high numbers in three pond water samples with high MIB levels, and low numbers in two other samples with low MIB levels. The organism was not present (less than one organism/10 ml) in nine other samples characterized by a “woody” or “swampy” odor and no detectable MIB. This Oscillatoria strain is believed to be the first blue-green alga that produces MIB ever isolated from Mississippi catfish ponds, and may be a cause of the off-flavor problem associated with MIB in those systems.     

Accumulation of nitrous oxide in aerobic groundwaters

N₂O concentrations in the groundwaters collected in the Kanto District and Nagano Prefecture in Japan and five counties in New York State were determined. These N₂O data were obtained from the water samples from wells, springs and seepages from soils in forests and cropping fields. The N₂O concentrations in all samples greatly exceeded those of atmospheric equilibration. The average concentration of 690 nM N₂O is one order of magnitude larger than that in deep ocean. All groundwaters of the present study were aerobic with a high level of NO₃⁻, but with the absence of NO₂⁻ and NH₄⁺, and with a very low level of dissolved organic carbon. These characteristics suggest that the nitrate respiration in the aquifers is of little significance for the production of N₂O.

ΔN₂O/NO₃⁻ molar ratios in the groundwaters were between 10⁻⁴ and 10⁻² (Δ indicates the excess gas over that which would be in equilibrium). This supports the above view since the observed N₂O yield agrees with that reported for the production during an ammonia oxidation. If nitrification was indeed a major mechanism for the production of groundwater N₂O, subsequent release of N₂O from the aquifers that are polluted with nitrogen may deserve more close attention as a potential source of atmospheric N₂O via diffusion and discharge.