NTA biodegradation and removal in subsurface sandy soil

This lab-scale study examined the biodegradation and removal of nitrilotriacetic acid (NTA) in the subsurface environment, mainly sandy soils. Batch tests indicated that NTA adsorption on the sandy soils played a minor role in its removal in these soils. Removal of NTA was investigated in 50.5 mm i.d. by 1.17 m long soil columns under unsaturated conditions at 15°C. Septic tank effluent containing 20 mg NTA l⁻¹ was dosed to soil columns four times a day at an overall loading rate of 1 gpd ft⁻² for a 43-day period. This feed NTA concentration was routinely reduced to a steady-state concentration of 0.1 mg l⁻¹ by passage through the 1.17 m of soil, after an indigenous soil microflora became sufficiently established over a 25 day period. In addition, the results of samples taken on day 21 demonstrated that greater than 75% removal of NTA can be expected in a soil depth of less than one-third meter.     

The effects of a chlorinated discharge and a thermal outfall on the structure and composition of the aquatic macroinvertebrate communities in the sheep river, Alberta, Canada

Physico-chemical and biological samples were collected from 12 sampling stations over a 13-month period to assess the effects of a small town's chlorinated sewage discharge and a thermal discharge on the Sheep River's macroinvertebrate communities. During the study, the chlorinated effluent plume was restricted to the left third of the channel for approx. 0.5 km at which point the effluent was thoroughly mixed due to an abrupt change in channel direction. Within the concentrated 0.5 km chlorinated plume, total residual chlorine TRC concentrations periodically exceeded 5.0 mg l⁻¹. Stations were categorized into similar community assemblages on the basis of species abundance and composition using heirarchical cluster analysis. Stations immediately downstream of the thermal outfall and those within the chlorinated plume had distinctly different structure and were dominated by Oligochaeta. Multiple discriminant analysis indicated that temperature was the principle discriminating variable immediately below the thermal discharge while the chlorinated sewage (MCSE) variable was the most important discriminant function within the chlorinated effluent plume. Following complete mixing of the effluent plume within the stream channel (0.6 km downstream of outfall), macroinvertebrate structure and diversity improved, presumably due to nutrient enrichment and dilution of TRC below detectable levels.     

Effect of temperature and dissolved oxygen on biodegradation of nitrilotriacetate

The effect of temperature and dissolved oxygen on the rate of biodegradation of nitrilotriacetate (NTA) was examined in water samples collected from the Rur River. Biodegradation of NTA was first order with respect to NTA concentration over a concentration range of 50–1000 μg l⁻¹. First order rate constants showed a typical temperature dependency (temperature coefficient, Q₁₀ = 2) and biodegradation of NTA was observed over a temperature range of 2–24°C. The effect of temperature on the rate of NTA biodegradation was described by the Arrhenius equation, with calculated activation energies in the range reported for ordinary enzyme reactions. Biodegradation of NTA was also observed at low dissolved oxygen concentrations (0.3 mg l⁻¹), although at reduced rates compared to high oxygen concentrations (13 mg l⁻¹). Biodegradation of NTA was oxygen-dependent, suggesting an obligate oxygen requirement for the initial steps in NTA metabolism by natural microbial communities in surface waters. In general, our results indicate that NTA biodegradation will occur in natural waters under conditions of low temperature and low dissolved oxygen and also at low NTA concentrations.     

Distribution of enteroviruses in sediments contiguous with a deep marine sewage outfall

The distribution of enteroviruses, coliforms, fecal coliforms and fecal streptococcus discharged from a raw sewage outfall pipe 3.6 km from shore at a depth of 44 m was studied. Enteroviruses and indicator bacteria were only isolated from water in an area within 200 m of the outfall. However, viruses were isolated from sediments as far as 3.6 km from the outfall at recreational bathing beaches. The concentration of enteroviruses in the sediment at the outfall boil ranged from 112 to 78 PFU l⁻¹ and 0 to 30 PFU l⁻¹ at the bathing beach. Indicator bacteria were not detected in the water or sediment at the bathing beach. Analysis of sediments for viruses may give a better idea of the long term distribution of sewage discharged from the outfall pipe.     

Mechanism of NTA degradation by a bacterial mutant

Transport of nitrilotriacetic acid (NTA) into the cytoplasm of a bacterial mutant was an active process. The mutant was able to degrade NTA from an initial concentration of 290,000 μg l⁻¹ of NTA to less than 50 μg l⁻¹ in 45 min, representing a rate of 486 μg NTA degraded per hour per mg dry weight of cells. This extremely fast rate of NTA utilization was substantiated by kinetic studies in which a Km of 82 μg l⁻¹ and a V_max of 370 μg h⁻¹ (mg dry weight cells)⁻¹ were found. The maximal temperature for NTA degradation was 50°C. The ability of the mutant to metabolize NTA resided mainly in the cell membrane fraction. Exchange diffusion technique showed that glycine and acetic acid were the metabolic products of NTA degradation. No iminodiacetic acid (IDA), succinate or citrate could be detected.     

Effects of trial disposal of acid-iron effluent from titanium dioxide production on the seafloor and epibenthic macroflora offshore from Koombana Bay, Western Australia

The effects of a trial discharge of acid-iron effluent, resulting from titanium dioxide production, on the seafloor and epibenthic macroflora offshore from Koombana Bay, Western Australia, were assessed. Approximately 88,0001 day⁻¹ of effluent containing 28 g l⁻¹ of iron and 137 g l⁻¹ of H₂SO₄ were discharged through a submarine pipeline from February 1976 to December 1977. This amount of effluent, constituting approx. 5% of total production, was intended to provide a guide as to the environmental effects on the seafloor of discharging the total amount of effluent.Preliminary studies suggested that discernible effects of the discharge were likely to be restricted to the immediate vicinity of the outfall. Consequently, surveys of the effects of the discharge were conducted by divers in December 1976 and April and December 1977 within 400 m of the outfall. The parameters measured were iron concentration in the surface sediment, number of macroscopic plant species (algae and seagrass) and leaf characteristics of the seagrass, Posidonia ostenfeldii. Additional observations on iron staining of the sediment and the condition of the macroscopic plants were also recorded by the divers.By December 1976, the outfall was surrounded by a zone, with a diameter of approx. 200 m, which was totally denuded of macroscopic plants. Extending further from the outfall was a zone in which some effects of the effluent (e.g. sediment stained by iron, reduction in macroscopic plants) were discernible. The total area of seafloor discernibly affected by the effluent in December 1977 when this study finished was 16 ha. At that time, the affected area may have still been increasing in size, and thus the figure of 16 ha must be considered only as the minimum area likely to have been affected by the discharge.     

Factors affecting nutrient loads in some Iowa streams

The export and concentration of inorganic nitrogen and total phosphorus from 34 watersheds in a northwestern Iowa lake district were measured during March 1971–August 1973. Annual nutrient losses were approximately 0.35 kg ha⁻¹ P. 6.7 kg ha⁻¹ NO₃-N, and 1.0 kg ha⁻¹ NH₃-N. A statistical analysis of the relationship between land-use and plant nutrients was used to determine differences among streams. Animal units in feedlots were significantly correlated with phosphorus and ammonia nitrogen (mg l⁻¹ and kg ha⁻¹ yr⁻¹). Nitrate nitrogen was negatively correlated with the percentage of watershed in marshland. Tile drainage and surface runoff from grasslands, feedlots, cornfields, and soybean fields were analyzed for nitrogen and phosphorus in spring 1974: mean values are given.     

The influence of nitrilotriacetic acid on heavy metal transfer in the activated sludge process—II. At varying and shock loadings

In laboratory simulations of the activated sludge process, the impact of shock loads of the detergent builders sodium tripolyphosphate (STPP) and nitrilotriacetic acid (NTA) on the transfer of heavy metals to the effluent, has been studied. Experiments have also been undertaken in which the influent concentration of each builder was doubled, in an endeavour to simulate the effect of a “wash day”. It is apparent from the data presented that NTA, when present under either of these conditions, resulted not only in deterioration of metal removal by the activated sludge process but caused a mobilisation of heavy metals from the sludge. Copper and lead were the metals most extensively affected. The mobilisation of heavy metals from the mixed liquor to the effluent in activated sludge units acclimated to NTA, upon a doubling of the influent NTA concentration, resulted from a failure by the activated sludge unit to completely degrade the additional NTA. The concentration of NTA in the effluent rose to 4.7 mg l⁻¹ following the increase in influent concentration. Ten days were required before effluent NTA concentrations returned to values equivalent to those prior to the increase in influent concentration. When condensed phosphates were added as shock load or upon the doubling of their influent concentration only the removal of copper was adversely affected.     

An improved microdesulphonation/gas liquid chromatography procedure for the determination of linear alkylbenzene sulphonates in U.K. rivers

An improved microdesulphonation/gas liquid chromatography (GLC) procedure is described for the specific determination of μg l⁻¹ levels of linear alkylbenzene sulphonates (LAS) in aqueous environmental samples including sewage, sewage effluent and surface waters. The LAS is concentrated from samples as its methylene blue complex by a large-scale solvent extraction and is then freed from potential interferences by a series of clean-up steps, i.e. ion-exchange chromatography, hydrolysis and solvent extraction, prior to its desulphonation with a concentrated phosphoric acid reagent. The resulting alkylbenzene hydrocarbons are recovered and quantitatively determined by a capillary GLC technique with the aid of internal standards (primary and secondary alkylbenzene sulphonate isomers) added at the initial concentration stage.The introduction of the clean-up stages, particularly a selective extraction of the LAS as the l-methylheptyl amine salt into hexane, has resulted in GLC traces that are free from major interferences and in which it is possible to readily identify LAS isomers on the basis of the relative retention times. The procedure has a limit of detection of less than 10 μg l⁻¹ LAS in a sample and allows the quantification of sub-μg l⁻¹ levels of individual isomers (C₉–C₁₅ homologues). The mean recovery of a C₁₂ LAS internal standard through the complete procedure is 91% for the environmental samples analysed.This procedure, together with a non-specific methylene blue colorimetric method (for determining anion surface active material), has been used in a monitoring exercise to establish the levels of LAS and methylene blue active substances (MBAS) in U.K. rivers and the River Rhine. A mean MBAS level of 0.15 mg l⁻¹ was found at the U.K. river sites selected (35 samples), of which only 26% on average was attributable to LAS by microdesulphonation/GLC analysis. However, the levels of LAS and its contribution to the total MBAS in rivers was found to vary with the nature of the sampling location, i.e. depending whether it was above, below or in the vicinity of a sewage effluent discharge. The distribution of the LAS isomers at these sites also showed differences that could be explained in terms of their relative biodegradabilities.     

Microbiological effects of wastewater effluent discharge into coastal waters of Puerto Rico

Microbiological effects of non-disinfected, combined chemical and domestic wastewater effluent discharge into coastal waters north of Barceloneta. Puerto Rico were investigated by membrane filter enumeration of fecal indicator bacteria and by enrichment isolation of specific pathogens. A wastewater plume was detected and delineated around the sewage outfall, located 800 m offshore and 30 m below the ocean surface. Fecal coliform and fecal streptococcus counts within the plume were significantly (F test) larger than comparable counts outside the plume. The shape and location of the plume was compatible with current patterns and prevailing winds and extended as far as 3.7 km west of the outfall, at which point the fecal coliform count was 146 100 ml⁻¹. The average non-plume fecal coliform concentration was 6.7 100 ml⁻¹. Specific pathogens isolated included Salmonella and Vibrio spp, including V. cholerae non-01 serovar isolated from a nearby river also impacted by the sewage plant.     

Pentachlorophenol biodegradation—II : Anaerobic

The fate of pentachlorophenol (PCP) during anaerobic digestion of sewage sludge solids was tested in a three phase protocol. Phase I involved acclimation; Phase II investigated biodegradation in semicontinuous-flow, stirred-tank reactors at solids retention times of 10, 20 and 40 days; phase III assessed the importance of nonbiological removal mechanisms and collected additional data concerning the extent of biodegradation. PCP was found to inhibit methanogenesis in unacclimated cultures at concentrations in excess of 200 μg l⁻¹ and thus acclimation of the digesters to PCP required very gradual increases in the influent concentration thereby allowing enrichment of organisms capable of degrading PCP. Once acclimation was achieved, digesters receiving influent containing 5.0 mg l⁻¹ PCP achieved stable operation with effluent PCP concentrations below 5 μg l⁻¹ at all retention times studied. Sorption was shown to be unimportant in PCP removal. Volatilization was considered to be unimportant based upon results obtained in forced aeration studies. This suggested that PCP was subject to at least primary biodegradation. Other evidence collected during the study indicated that more complete biodegradation probably was occurring.     

The effect of surfactants on the mixed chelate extraction-atomic absorption spectrophotometric determination of copper, nickel, iron, cobalt, cadmium, zinc and lead

Twelve surfactants representing pure cationic, anionic and non-ionic detergents, three commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap, nitrilotriacetic acid (NTA), EDTA, and humic acid were investigated for their effect on the extraction-atomic absorption spectrophotometric determination of copper, nickel, iron, cobalt, cadmium, zinc and lead. Cations were extracted into 10 ml of a solution containing diphenylthiocarbazone, 8-quinolinol and acetyl acetone in ethyl propionate. To avoid emulsion formation, the maximum concentration of linear alkylate sulphonate (LAS) was 10 mg l⁻¹ and for solid industrial LAS-type detergent was 50 mg l⁻¹, but washing powder did not interfere at 100 mg l⁻¹. Cationic and non-ionic detergents gave low recoveries for cobalt. Condensed phosphates at a concentration of 20 mg l⁻¹ did not cause significant interference. NTA interfered with nickel extraction and EDTA with all metals. Humic acid, however, gave no interference. A standard addition procedure can be used to correct the results.A comparison is made between the APDC-MIBK and the mixed chelate-ethyl propionate methods for the determination of trace metals in the presence of various surfactants in natural waters; the latter is preferable.     

The use of uric acid as a method of tracing domestic sewage discharges in riverine, estuarine and coastal water environments

The chemical tracking of sewage effluents discharged into fresh and saline waters presents difficulties, especially in estuaries. The main difficulty is caused by the dissolved constituents being used to monitor the effluent also occurring naturally at similar levels. Uric acid is present at significant levels in untreated sewage and is not normally found in unpolluted waters. Until now no suitable routine method has been available for uric acid estimation in fresh and saline waters at levels normally encountered in the environment. In this paper we describe a recently developed technique using high-performance liquid chromatography which estimates uric acid in both fresh and saline waters in the range 1–10,000 μg l⁻¹ with a precision (2σ) of ±20% at 2 μg l⁻¹, ±4% at 40 μg l⁻¹ and ±2% at 10 mg l⁻¹.     

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.     

Direct analytical procedure for determination of volatile organic acids in raw municipal wastewater

A direct analytical method for identification and determination of the individual volatile acids in raw sewage was developed. The proposed procedure is rapid, omitting tedious sample pretreatment and thus avoiding possible losses involved in steam distillation, evaporation or extraction. It consists of direct injection of raw sewage into a gas chromatograph, including Carbowax 20 M on acid washed Chromosorb W column and a flame ionization detector. Sample preparation is confined to addition of solid metaphosphoric acid to the raw sewage, and removal of precipitated proteins and suspended solids by centrifugation.The direct injection method proved to be practicable, accurate and rapid. Volatile acids content in raw municipal sewage in Haifa, Israel, was found to be in the range of 150–160 mg l⁻¹, of which 120–125 mg l⁻¹ was acetic acid, 30–33 mg l⁻¹ propionic acid, 6–8 mg l⁻¹ butyric acid, 2 mg l⁻¹ isovaleric acid, and 0.5–1 mg l⁻¹ valeric acid.     

Disinfection of viruses in sewage by ozone

The action of ozone on poliovirus was examined employing two different methods. In the first, the filtered sewage together with a virus inoculum was added to a buffer solution which contained known concentrations of ozone. The most outstanding finding was the complete disappearance of the ozone immediately after the addition of the effluent. At the same time, there was a rapid reduction in virus titer. However, after the initial reduction, the virus titer remained unchanged. The degree of virus inactivation was dependent on ozone concentration and on the amount of organic matter in the effluent. With increased ozone concentration and decreased organic matter, a larger percentage of viruses were inactivated. With the second method, ozone was bubbled into filtered sewage containing a virus inoculum. Inactivation of the virus started after a lag period of about 30 s. even before ozone residual in the sewage was detected. Inactivation of 99.999% of the virus was obtained when the ozone residual was about 0.6 mg l⁻¹. In similar experiments performed with buffer instead of sewage, the entire process took place at a much faster rate. When ozone concentrations reached about 1.0 mg l⁻¹. 99.999% of the virus was inactivated. In conclusion, ozone was found to be a very potent viral disinfectant, even in contaminated water.     

Effect of surfactants on the determination of aluminium in waters

Eleven surfactants representing pure cationic, anionic and nonionic detergents, four commercial detergents, sodium pyrophosphate, sodium tripolyphosphate, a soap and nitrilotriacetic acid (NTA) were investigated for their effect on the determination of aluminium in water using the eriochrome cyanine R, ferron-orthophenanthroline and chrome azurol S methods. Cationic, anionic and nonionic detergents at concentrations up to 2, 100 and 1000 mg l⁻¹, respectively, did not interfere. Sodium tripolyphosphate interfered badly above 1.0 mg l⁻¹, and therefore the interference by formulated detergents containing tripolyphosphate was serious. Concentrations of NTA, soap and sodium pyrophosphate had to be below 0.5, 10 and 20 mg l⁻¹, respectively, to limit the error to 5%.     

Proportion of methylmercury to the total amount of mercury in river waters in Canada and Japan

The proportions of methylmercury to the total amount of mercury in water were determined for three rivers and were found to be similar (around 30%). The proportion in sewage effluent water showed a similar value. A pretreatment procedure which can analyze a low concentration of mercury and various species of mercury compounds in natural water is described. The mercury concentration in once mercury-polluted rivers was reduced considerably to near background levels (Ottawa River: 6.6 ng l⁻¹; Suimon River: 26.2 ng l⁻¹).     

Effect of surfactants on the determination of sulphate in waters

The effects of pure cationic, anionic and non-ionic detergents, industrially prepared detergents, sodium tripolyphosphate, sodium pyrophosphate, soap and NTA, in quantities up to 1000 mg l⁻¹, on the analysis of soluble iron in water using the phenanthroline, tripyridine and biquinoline methods were investigated. The tripyridine method is superior to the other two methods for the determination of iron in the presence of up to 1000 mg l⁻¹ of various surfactants but not for up to 100 mg l⁻¹ of non-ionic detergents. The phenanthroline method can be used to determine iron in the presence of up to 1000 mg l⁻¹ of cationic, anionic and non-ionic detergents, but sodium tripolyphosphate interfered above 2 mg l⁻¹. The biquinoline method can be used for the determination of iron in the presence of up to 1000 mg l⁻¹ of cationic, 100 mg l⁻¹ of anionic and 70 mg l⁻¹ of non-ionic detergents, and 50 mg l⁻¹ of sodium tripolyphosphate.     

Role of aquatic plants in wastewater treatment by artificial wetlands

This report describes investigations using artificial wetlands which quantitatively assess the role of each of three higher aquatic plant types, Scirpus validus (bulrush), Phragmites communis (common reed) and Typha latifola (cattail), in the removal of nitrogen (via sequential nitrification-denitrification), BOD and TSS from primary municipal wastewaters. During the period August 1983–December 1984, the mean ammonia concentration of 24.7 mg l⁻¹ in the primary wastewater inflow (hydraulic application rate = 4.7 cm day⁻¹) was reduced to mean effluent levels of 1.4 mg l⁻¹ for the bulrush bed, 5.3 mg l⁻¹ for the reed bed and 17.7 mg l⁻¹ for the cattail bed, as compared to a mean value of 22.1 mg l⁻¹ for the unvegetated (control) bed. For all three vegetated beds, the mean effluent ammonia values were significantly below that for the unvegetated bed and for the inflow. The bulrushes and reeds (in that order) proved to be superior at removing ammonia, both with mean effluent levels significantly below that for the cattail bed. The high ammonia-N (and total N) removal efficiencies shown by the bulrush and reed beds are attributed to the ability of these plants to translocate O₂ from the shoots to the roots. The oxidized rhizosphere so formed stimulates sequential nitrification-denitrification. Similarly BOD removal efficiencies were highest in the bulrush and reed beds, both with mean effluent BOD levels (5.3 and 22.2 mg l⁻¹, respectively) significantly below that for the unvegetated bed (36.4 mg l⁻¹) and equal to or better than secondary treatment quality (30 mg l⁻¹). Our results demonstrate that higher aquatic plants can indeed play a significant role in secondary and advanced (N removal) wastewater treatment by wetland systems, a role that is completely distinct from that associated with their pollutant uptake capacity.