The inactivation kinetics of H-1 parvovirus by chlorine

A newly isolated enteric virus has recently been found to be associated with large outbreaks of waterborne gastroenteritis. Most commonly referred to as the Norwalk agent, this virus appears to be morphologically and biophysically similar to the parvoviruses. In this study the parvovirus H-1, a putative human virus containing single-stranded DNA, was used as a model virus for chlorine inactivation experiments. The objective of this research was to investigate the kinetics of inactivation of this virus by low levels of free chlorine (0.05–0.20 mgl⁻¹) at pH 7 and at 5, 10, 20 and 30°C.Inactivation occurred in the usual dose-response relationship, that is, increasing the chlorine dose caused an increase in the rate of inactivation. The energy required for the inactivation reaction using 0.05 mgl⁻¹ free chlorine from 5 to 30°C was graphically determined to be 2.4 kcal mol⁻¹. The change in entropy was calculated to be -52.34 entropy units. For disinfection purposes, the time required for 99% inactivation of H-1 parvovirus at pH 7.20°C and a chlorine dose of 0.2 mgl⁻¹ free chlorine was 3.2 min. The parvovirus H-1 appeared to be less resistant to free chlorine than poliovirus type 1 (LSc).     

The stability of bovine parvovirus and its possible use as an indicator for the persistence of enteric viruses

Bovine parvovirus 1 (Haden virus) gives with grown in 0–24 h secondary cultures of calf kidney a pronounced CPE. The virus is very thermoresistant, it takes e.g. at 60°C 6 h to decrease the titer of infectivity 1 log unit.When seeded in liquid manure the virus becomes inactivated at a rate of around 6–8 days for 1 log unit under aerobic conditions at 5–20°C. The inactivation under anaerobic conditions is very temperature dependent: at 5°C it takes about 200 days to decrease the titer 1 log unit, but at 20°C a rate of inactivation of 20 days per log unit of virus was found.It is suggested that the bovine parvoviruses may be useful as indicators in connection with evaluations of the importance of viral bovine faecal pollution. For evaluations of treatment efficiencies it is suggested that these parvoviruses may also be used as indicators for human enteric viruses like the virus of infectious hepatitis.     

Determination of chloride in water with a HgS/Hg2Cl2 electrode

The application of a new type of solid state chloride ion sensitive electrode, based on HgS/Hg₂Cl₂ has been investigated for manual and automated measurements of chloride in natural, industrial and waste water. The electrode displays Nerstian response for the range 0·05–3·500 ppm of chloride and can be used for concentrations down to 0·05 ppm (5 × 10⁻⁷m). Achieved values of standard deviation, recovery and comparative tests from a variety of water samples are highly satisfactory. Inherent simplicity and sensitivity together with obtained results demonstrate the usefulness of the proposed method in routine analyses.     

Determination of ozone in water by the indigo method

The concentration of aqueous ozone can best be determined by the decolorization of indigo trisulfonate (600 nm, pH below 4) whenever the ozone cannot be measured directly by its u.v. absorption. The method is stoichiometric and extremely fast. The change of absorbance vs ozone added is −2.0 ± 0.1 × 10⁴ M⁻¹ cm⁻¹ and is independent of the concentration of aqueous ozone in the range 0.005–30 mg 1⁻¹. The precision of the analysis is 2% or 3 μg 1⁻¹ for low concentrations if a spectrophotometer or a good filter instrument is used. Visual methods can be used to measure 0.01 mgl⁻¹ ozone. Secondary oxidants produced by ozone in natural water, including hydrogen peroxide or chlorite, do not interfere; chlorine can be masked. The reagent solution is stable for 3 months. The method is recommended for kinetic measurements, for studies of ozonation processes and for visual field methods.     

Uptake of cadmium, zinc, copper, lead and chromium in the pacific oyster. Crassostrea gigas. Grown in the tamar river. Tasmania

Hundreds of oysters and mud samples from 15 sites along the Tamar River were analysed for cadmium, copper, zinc, lead and chromium. The widely accepted concept of enrichment factors of up to several hundred thousand, describing accumulation by oysters of cadmium, zinc and copper from seawater has been found to be grossly misleading. Concentrations found for these three metals in oysters were only 10–40 times the concentrations in inhabited muds. Concentrations of metals in muds may be used to indicate whether a potential oyster bed would produce oysters that were grossly contaminated. Approximately 1 ppm cadmium in mud could result in oysters containing at least 25 ppm, i.e. 4–5 ppm wet wt. Similarly. 100 ppm zinc in mud could produce oysters containing at least 4000 ppm. i.e. 800–1000 ppm wet wt. Three heavy metal accumulation processes were discernible. Copper and chromium appeared to be absorbed up to a maximum weight that was limited by the size of the oyster and was independent of the amount of metal in the mud. Lead was not absorbed through any physiological demand, but was randomly incorporated at sites containing high concentrations in the mud. Zinc and cadmium were accumulated by a process that depended primarily on the concentrations of these metals in the mud at each site. Mean dry wt concentrations of metals in oysters and mud samples ranged from: 4.2–134 ppm and 0·4 to 5·7 ppm cadmium; 200–1700 ppm and 3–224 ppm copper: 0 135 ppm and 4–1500 ppm lead: 1–37 ppm and 2–88 ppm chromium; 1700 14.000 ppm and 20–500 ppm zinc. respectively.     

Experimental simulation of biodegradation in rivers: Oxygen, organic matter and biomass concentration changes

Dissolved oxygen (DO) and biochemical oxygen demand (BOD) concentration changes after an organic matter discharge into a river have been studied in the absence of oxygen transfer. According to these laboratory experiments, biodegradation of various organic compounds (glucose, glutamic acid, starch, ovalbumin and ethanol) in Seine river samples incubated at 15 30°C follow a biphasic behaviour. During a lag-phase of 10–20 h, DO decreases linearly (0.12 ppm h⁻¹ at 20°C), whereas BOD is constant. During a subsequent aerobic exponential phase, DO and BOD uptake are proportional and increase exponentially with time (0.13 h⁻¹ at 20°C). Using cell ATP as biomass indicator, the latter phase was shown to correspond to a cell division step. A kinetic model was developed for stimulating DO and BOD concentration changes after a waste water discharge at temperatures ranging between 15 and 30°C.     

Rotavirus and reovirus stability in microorganism-free distilled and wastewaters

Survival of calf rotavirus and reovirus under controlled laboratory conditions in microorganism-free, distilled and wastewater at 8 and 26°C was examined by periodic measurement of cytopathic effects (CPE) and indirect fluorescent antibody (IFA) assays. Five samples of both water-types were collected and inoculated with the two viruses. Three samples of each type of water were divided into two bottles, one per virus, for incubation at 8°C. Two samples were used at 26°C, one per trial. In the absence of light and shaking at 26°C, 7–13 days were required for a loss of 90% infectivity for rotavirus and reovirus, while at 8°C, averages were 80 days for rotavirus and 260 days for reovirus. Virus infectivity remained for more than 30 days at 26°C and 400 days at 8°C. Rates of decline were 10–100 times greater at 26 than at 8°C, but at both temperatures, the MPN log₁₀ rate of decline of infectivity was linear.     

Removal of viruses from water by sorption on coal

The objective of this research was to investigate the potential of bituminous coal as sorbent for removing viruses from water and to delineate the sorption mechanism(s). This study was undertaken in view of the increasing use of coal in water and wastewater treatment. Bacteriophage T4 against Escherichia coli BB was used as a model virus and coal samples from Neyveli and Giridih were used as sorbents. A sampling method for rapid separation of unsorbed viruses from the sorbent was standardized which consisted of filtering the sample containing coal and viruses through a Whatman filter paper soaked in beef extract. Effects of the following parameters on virus sorption were investigated: pH, ionic strength, temperature, and presence of proteinaceous matter.Maximum virus sorption (about 70%) was observed at pH 8·0 with input virus concentration 1·44 × 10⁴ PFU ml⁻¹, coal size 350 μm and ionic strength 0·02. Optimum ionic strength for virus sorption was found to be 0·015. Higher temperatures increased the sorption capacity and the activation energy was found to be 30·3 kcal/mole. This and low desorption values (6–10%) suggested irreversible chemisorption. Effect of carbon content of coal on sorption-desorption was studied using pure graphite which showed negligible desorption. Effect of proteinaceous matter was investigated using 5% domestic wastewater and the culture broth. Proteinaceous matter appeared to compete with virus for sorption sites on coal and reduced sorption by about 12%.Kinetics and equilibria of sorption on Neyveli coal at pH values 5·5, 7·1 and 8·0 were studied in a non-flow agitated system. Equilibrium sorption was attained in 90 min, the bulk of it being over in 45 min. Sorption data followed Langmuir type isotherm plots and suggested L2 type plot according to Gile's classification (J. Chem. Soc. Part 3, p. 3973, 1960). Isotherm plot with 5% domestic wastewater gave an S curve, suggesting moderate to large intermolecular attraction and implying strong competition for substrate sites from molecules of the solvent. Monomolecular coverage to the extent of only 0·1% of total surface area agreed with the assumptions of isotherm plot and penetration into micropores and macropores of coal was ruled out.     

Influence of temperature and u.v. light on disinfection with ozone

An inactivation study was performed with ozone in two laboratory-scale, continuous flow systems to determine the effects of temperature and u.v. light on the survival of Mycobacterium fortuitum, a potential microbial indicator for disinfection efficiency. Four temperatures were investigated in the range of 9–37°C. It was determined that a higher degree of inactivation occurred with ozone at elevated temperatures. The activation energy for M. fortuitum was found to be 18.3 kcal.When u.v. light was employed as a catalyst with ozone disinfection, there was no apparent increase in the degree of inactivation of M. fortuitum in either the clean system (deionized water-phosphate buffer) or secondary wastewater effluent. However, u.v. light in itself exerted a strong disinfecting effect.     

Inactivation of Naegleria gruberi cysts by chlorine dioxide

Investigations were carried out to determine the kinetics of chlorine dioxide inactivation of Naegleria gruberi cysts and the influence of pH from 5 to 9, temperature from 5 to 30°C, cyst age from 3 to 12 days, and cyst clumping. Inactivation was characterized by an initial concave downward shoulder followed by an essentially linear portion but the process obeyed Watson's Law. At 25°C and pH 7 the mean concentration time product for 99% inactivation was 5.5 mg·min l⁻¹. These products varied inversely with temperature and pH.     

Semi-automated ammonia probe determination of Kjeldahl nitrogen in freshwaters

A commercially available ammonia probe was used in an automated continuous flow-through system to determine the ammonia-N concentration in Kjeldahl digests of fresh waters. The method is suitable for samples with Kjeldahl-N concentrations greater than 0·1 mg N.1⁻¹. In the 0·1–1·0 mg N.1⁻¹ range 10 digests.h⁻¹ can be analysed. Only micro-digestion equipment and sample volumes of 25 ml are required. The ammonia probe with modified filling solution and polytetafluoroethylene membrane is sufficiently stable for continuous use throughout a working day. Analyses of Kjeldahl digests of freshwater samples by this method and the distillation-Nesslerisation procedure showed good agreement. More precise results were obtained by the ammonia probe method. The ammonia probe method obviates the steam-distillation operation which is time-consuming and during which errors can be easily introduced by loss or gain of ammonia.     

The effect of arsenic on embrional development of rainbow trout (Salmo gairdneri, RICH.)

Studies were made on the toxic effect and accumulation of arsenic in developing eggs of rainbow trout. Fertile eggs were incubated at 6–7°C in sodium arsenate or arsenic trioxide solution at concentrations of 0.05–50.0 ppm As. The effect of arsenic on the survival of embryos and on the accumulation of the element in eggs were found to be related to the arsenic concentration and to the arsenic compound used (value of As-ion).     

Determination of labile and strongly bound metals in lake water

Differential pulse anodic stripping voltammetry is applied to differentiate and determine the labile and strongly bound forms of Zn, Cd, Pb and Cu in lake water without preconcentration of the sample. The sensitivities as established for an oxidation peak current of 0·020 μA are: 0·2 ppb for Zn. 0·4 ppb Cd. 0·7 ppb Pb and 0·5 ppb for Cu. For the analysis of a lake water containing 5·0–24·5 ppb of the four metals, the relative S.D. ranged from 1·6 to 10 per cent. Interferences of cations and anions and the choice of a buffer system have been discussed. The method has been applied to study a number of small lakes in the Sudbury area. Ontario.     

Response of zebra mussel veligers to chemical oxidants

Experimental studies using chlorine, hydrogen peroxide and ozone showed two responses by zebra mussel veligers. First, veligers readily perceived the presence of oxidants (> 0.1 mg/l for chlorine and ozone) and responded by retracting the velum and ceasing swimming and feeding activities. Under these conditions, veligers are prevented from attaching to solid surfaces. Second, continuous exposure to these oxidants caused death. Complete mortality by chlorine or ozone (0.5–1 mg/l) at 18–22°C required continuous exposure of about 18 and 5 h, respectively. Either chlorine or ozone should be effective in controlling zebra mussel veligers. Hydrogen peroxide was observed to be effective in preventing attachment but only at high doses relative to chlorine and ozone.     

Ozonation of water containing chlorine or chloramines. Reaction products and kinetics

Ozone reacts with free aqueous chlorine when present as hypochlorite ion (OCl⁻) with a second order rate constant of 120 ± 15 M⁻¹ s⁻¹ at 20°C. About 77% of the chlorine reacts to produce Cl⁻ and 23% is oxidized to ClO⁻₃. No ClO⁻₄ is formed. Conversion of chlorine to monochloramine reduces the ozone reaction rate to 26 ± 4 M⁻¹ s⁻¹, independent of pH, NH₂Cl is transformed quantitatively to NO⁻₃ and Cl⁻ by O₃. Rate data for other chloramines are also presented. The direct reaction of ozone with chlorine accounts for a significant amount of the chlorine and ozone demand found when the two oxidants are used in combination under water works conditions.     

Oxygen consumption and activity of the white sucker (Catostomus commersoni), in lethal and nonlethal levels of the organochlorine insecticide, methoxychlor

The survival, oxygen consumption and spontaneous activity of suckers were determined at 15°C in water containing different concentrations of methoxychlor in ethanol, ethanol, and no added substances. A dynamic bioassay was used to estimate the 96 h LC50, which was found to be 0·0345 ppm. Routine oxygen consumption was determined in a continuous-flow respirometer, and the activity was recorded in separate experiments by measuring the water disturbance using silver wire electrodes.After 24 h fish exposed to untreated, ethanol-treated and 0.01 ppm methoxychlor-treated water had oxygen uptake rates which were relatively constant and near standard levels. At 0.10 ppm methoxychlor (lethal to all fish within 85 h), oxygen consumption rates were 2–3.5 × as high as those of control fish. Activity also greatly increased. The fish lost their balance along with the coordination between opercular and locomotor movements. Suckers that died in 0.04 ppm methoxychlor showed oxygen uptake rates and poisoning symptoms similar to 0.10 ppm treated fish, while those that survived this treatment had rates similar to control fish. The increase in ventilation which accompanies this hyperactivity may result in increased uptake of insecticide and thereby explain the irreversible nature of the response.     

Optimized back-analysis for tunneling-induced ground movement using equivalent ground loss model

Application of an optimization technique for the back-analysis of tunneling-induced ground movement is presented in this paper. The conjugate gradient method was adopted for the optimization procedure and the gap parameter model was utilized to evaluate the ground movement. According to the results of back-analysis using the monitoring data of the Taipei Rapid Transit System, the angle of the influence zone of ground settlement is approximately 45° for tunneling in clayey soils, and that for sandy layers ranges from 30 to 50°. Backfill grouting will reduce the physical gap of shield machine in the order of 60–80% for tunneling in clayey soils and in the range of 70–85% for sandy layers. Semi-empirical equations were established to predict the tunneling-induced ground movement in the silty clay and silty sand of Taipei basin. Case studies were presented to demonstrate that the adoption of the method can provide a reasonable prediction of the ground settlement due to shield tunneling.     

The loss of poliovirus 1 infectivity in marine waters

The loss of infectivity (LOI) of poliovirus 1 in marine water from the Gulf of Mexico was studied. Typically, three logs of infectivity were lost in 5–6 days at 24°C. Experiments described in this report suggested that this LOI was not a result of container adsorption or virion aggregation: nor was a resistant component within the stock virus found that would have explained the two-component curves often observed with the virus loss. Viral infectivity loss occurred in raw, filter-sterilized, and autoclaved marine water. Loss was also observed when the virus was suspended in artificial seawater of 1, 10 and 20 g kg⁻¹ salinity. No explanation for the LOI other than true inactivation of the virion was found. The specific component(s) of marine water responsible for virion inactivation remains to be ascertained.     

Denitrification with a bacterial disc unit

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

Water quality criteria for European freshwater fish: Report on ammonia and inland fisheries

In establishing water quality criteria for European inland fisheries, the effect of ammonia is an important factor to be considered. Sewage effluent, effluents from certain industries and from agriculture are common sources of ammonia in water.The harmful effects of ammonia on fish are related to the pH value and the temperature of the water due to the fact that only the un-ionized fraction of ammonia is poisonous. The un-ionized fraction increases with rising pH value, and with rising temperature.Fish differ slightly in their tolerance to ammonia depending on species. The difference in tolerance being more significant for short periods of exposure. The difference in tolerance is, however, not great enough to justify different criteria for different species.The lowest toxic concentration found for salmonids is 0·2 mg NH₃ 1⁻¹ (un-ionized), but other adverse effects caused by prolonged exposure are only absent at concentrations lower than 0·025 mg NH₃ 1⁻¹ (un-ionized). Concentrations of total ammonia which contain this amount of un-ionized ammonia vary from 19·6 mg 1⁻¹ (pH 7·0, 5°C) to 0·12 mg 1⁻¹ (pH 8·5, 30°C).The criterion should not be applied to temperatures below 5°C or to pH values above 8·5 when other factors have to be taken into consideration.