A 13-month survey of nematodes at three water treatment plants in southern Ontario, Canada

Nematodes were present in almost every sample of treated water from all 3 plants examined, often in high numbers (a maximum of 42.5 1⁻¹), with a considerable proportion being motile. Existing suggested standards of nematode concentrations were exceeded at each plant. Treatment processes, including coagulation, filtration and chlorination, were ineffective in immobilizing or removing most nematodes. The most significant factor in reducing nematode densities in this study was a slow-moving canal at one plant which acted as a presettling tank.High river flow, heavy rainfall and high raw water turbidity all corresponded to increases in nematode concentrations and can be used to indicate those times when extra measures to reduce numbers might be applied.Further research is recommended on the supposed pathogen carrying abilities of nematodes in drinking water.     

Effects of microelements on soil nematode assemblages seven years after contaminating an agricultural field

Long-term effects of Cd, Cr, Cu, Se and Zn were studied 7 years after artificially contaminating plots of an agricultural field on a calcareous chernozem soil. Effects of three to four different contamination levels (originally 10, 30, 90 and 270 mg kg⁻¹) were studied. Nematode density was significantly reduced by 90 and 270 mg kg⁻¹ Se as well as by 270 mg kg⁻¹ Cr, while 90 and 270 mg kg⁻¹ Se also reduced nematode generic richness. Maturity Index values (calculated for c-p 2–5 nematodes) consistently decreased with increasing Cr and Se concentration and to a lesser extent in Zn plots as well. Structure Index showed decreasing trends in increasing Cr, Se and (to a lesser extent) in Zn treatments, while in Cd it shows a moderate increase. Distribution of c-p groups was negatively affected by the increasing Cr and Se concentration, while in Zn plots, this decrease was not significant. Response of feeding groups to pollutions was similar to other parameters: Cr and Se caused significant changes toward the loss of variability. The proportion of the most sensitive omnivorous and predatory nematodes decreased clearly as a consequence of Cr and Se treatments. Zn pollution also resulted in a slight decrease in this group, while Cd caused an increase. Nematode diversity profiles showed a significant decrease in the plots of increased Cr and Se concentrations, while increased concentrations of Cu and Zn resulted in ambiguous effects. Besides providing evidence on the harmful effects of Cr and Se on a soil nematode assemblage, our results suggest that simultaneous analysis of Maturity Index, Structure Index and diversity profiles provide a promising tool in nematological indication of soil pollution.     

Sedimentation of helminth eggs in water

Helminth parasite eggs in low quality water represent health risks when used for irrigation of crops. The settling velocities of helminth eggs (Ascaris suum, Trichuris suis, and Oesophagostomum spp.) and wastewater particles were experimentally determined in tap water and in wastewater using Owen tubes. The settling velocities of eggs in tap water was compared with theoretical settling velocities calculated by Stoke’s law using measurements of size and density of eggs as well as density and viscosity of tap water. The mean settling velocity in tap water of 0.0612 mm s⁻¹ found for A. suum eggs was significantly lower than the corresponding values of 0.1487 mm s⁻¹ for T. suis and 0.1262 mm s⁻¹ for Oesophagostomum spp. eggs. For T. suis and Oesophagostomum spp. eggs the theoretical settling velocities were comparable with the observed velocities in the Owen tubes, while it was three times higher for A. suum eggs. In wastewater, the mean settling velocity for A. suum eggs (0.1582 mm s⁻¹) was found to be different from T. suis (0.0870 mm s⁻¹), Oesophagostomum spp. (0.1051 mm s⁻¹), and wastewater particles (0.0474 mm s⁻¹). This strongly indicates that in low quality water the eggs are incorporated into particle flocs with different settling velocities and that the settling velocity of eggs and particles is closely associated. Our results document that there is a need to differentiate the sedimentation of different types of helminth eggs when assessing the quality of low quality water, e.g. for irrigation usage. The results can also be used to improve existing models for helminth egg removal.     

Optimization of electro-oxidation and electro-Fenton techniques for the treatment of oilfield produced water

Electrochemical advanced oxidation processes are the most promising methods for destroying and degrading organic and inorganic pollutants present in produced water effluents. This study presents the electro-oxidation process using graphite electrodes and electro-Fenton process using iron electrodes for the treatment of real produced water. The effect of operating parameters such as current density on chemical oxygen demand (COD) removal efficiency was addressed. The result showed that electro-Fenton process was more efficient than electro-oxidation process where it gave 98% as maximum COD removal efficiency with energy consumption of 1.9 kWh/dm³ at H₂O₂ concentration of 12 mM, current density of 10 mA/cm², temperature of 25°C, pH of 3, and treatment time of 80 min compared with 96.9% as maximum COD removal efficiency with energy consumption of 3 kWh/dm³ at pH of 6, current density of 10 mA/cm², temperature of 40°C, and reaction time of 80 min when using electro-oxidation process. These results demonstrated that electrochemical technologies are very promising methods for the treatment of produced water from oil/gas industry, so it can be safely disposed of or effectively reused for injection and irrigation.     

Physicochemical properties and biological activity of the water depleted of heavy isotopes

Data on physicochemical properties of the light water (deuterium concentration is reduced to the ratio D/H = 4 ppm and that of the isotope of oxygen 18—to the ratio ¹⁸O/¹⁶O = 750 ppm) have been obtained. They include the melting and boiling points, kinematic viscosity, density, the spin-spin proton relaxation time, self-diffusion coefficients, and the small-angle laser light scattering. It was found out that the biological activity of the light water was determined by the mechanisms different from the ligand-induced toxic effects. An explanation was proposed for the detected significant changes of the light water as compared with the high-resistivity water having geochemically ordinary isotope composition. This explanation was based on the mechanism of formation of supramolecular density inhomogeneities in water representing the deuterium-stabilized heterophase clusters.     

Characteristics of air pressure fluctuations in high-rise drainage stacks

Maximum air pressure in a drainage stack can deplete the appliance water trap seals that prevent the ingress of foul gases and odors into a habitable space. This study investigates the air pressure fluctuation frequency, as well as the maximum and average air pressures with their respective standard deviations, in a 38 m high drainage stack of a full-scale experimental tower under steady flow conditions of flow rates 1 Ls⁻¹ to 4 Ls⁻¹ discharging at a height between 15 m to 33 m above the stack base. Mathematical expressions are proposed to correlate the maximum air pressure with the probability density function of the data measured. The average prediction and the maximum under-prediction of the absolute peak pressure were determined with the margin of error taken within certain confidence levels. It was demonstrated that water seal failure would likely be occurred at some heights below the discharge locations. The outcome enhances the understanding of the characteristics of air pressure fluctuation within a drainage stack of a high-rise building.     

The dynamics of suspended algal populations in the lower Wye catchment

The algae of the R. Wye and its tributary the R. Lugg were described principally from samples collected from 7 sites in the lower Wye catchment during 1980 and 1981. The density of algae in the Wye was found to be correlated with river flow and solar radiation, highest numbers (12.5 × 10⁵ cells ml⁻¹), principally of Scenedesmus and Cyclotella, occurring at low stable flows and relatively high solar radiation. Algal populations in the Lugg were much smaller ( 1.3 × 10³cells ml⁻¹) than those of the Wye and were principally composed of species derived from the periphyton. Downstream increases in load (cell density × flow) of both Scenedesmus and Cyclotella in the Wye were generally equivalent to about 0.3 division d⁻¹; these rates were lower than those obtained in laboratory culture and this was probably largely related to underestimates arising from algal removal by filter feeders (principally simuliid larvae). Potential problems arising from the treatment of Wye water supporting substantial algal growths are considered: these include haloform production, deoxygenation in a transfer pipeline, algal penetration into potable supply and taste and odour.     

Zur Absch?tzung von W?rmeleitf?higkeiten der oberfl?chennahen Lockergesteinsschichtenfolge in Norddeutschland

In the course of a groundwater investigation program in east Schleswig-Holstein, groundwater temperature measurements were performed in groundwater observation wells. First, the heat flux density of the investigation area was determined. The heat flow ranged from 20 to 77?mW?m^?2. Near the boundaries of the area, subsurface salt structures cause an increase in heat flow to the earth’s surface. In the centre of this region the heat flow is due to convective processes, and is somewhat low. Here the groundwater recharge as well as the influx from top to bottom affects the temperature field. By means of heat flux densities and the measured temperature gradients, the thermal conductivity was estimated. For clays in the study area the thermal conductivity averaged 1.4?W?m^?1?K^?1 ranging between 1.1 and 1.7?W?m^?1?K^?1. For the coarse grained sand the conductivity was 3.0?W?m^?1?K^?1 and for the fine sands it was 2.8?W?m^?1?K^?1. Due to its heterogeneity, the thermal conductivity of the till ranged between 1.6 and 2.8?W?m^?1?K^?1, depending on the mineralogical composition, the bulk density and the water content of the till. The average thermal conductivity was 2.1?W?m^?1?K^?1.     

Field Placing Test of Lightweight Treated Soil under Seawater in Kumamoto Port

A lightweight treated soil method has recently been developed to reuse dredged soils as artificial lightweight geomaterials, the density of which ranges from 1.0 ~ 1.2 g/cm³, for coastal construction projects. In the two types of lightweight soils, foam-treated soil (FTS) and bead-treated soil (BTS), the slurry of dredged soil is mixed with cement and air foam, or cement and EPS beads (the diameters are 1 ~ 3 mm), respectively. The lightweight treated soil method have been applied in several seaports and coastal airport projects, but only in the sites at a level shallower than –3 m to avoid density change due to large water pressure and the possibility of washout during underwater placing.In this study, full scale field placing tests of lightweight soils were carried out at sites 10 m below the sea level in Kumamoto Port with the purpose of investigating the material properties of lightweight soils placed under deep water. Especially the change of density through the process of mixing, transportation, placing and hardening was examined in detail. It was found that the lightweight soil method can be applied under sea water of –10 m, although a part of the total volume of mixed foam or mixed EPS beads is swept away during the construction process. However the wet-density of lightweight soil measured 1 year after the construction was almost the same as that of a 28-day specimen, while the 1 year strength was 40% larger than the 28-day strength.     

Some chemical properties of hazelnut husk and its suitability for particleboard production

Hazelnut husk is a renewable natural resource that has not industrial utilization yet. The objective of this study was to examine some chemical properties (holocellulose, cellulose, lignin and ash contents, alcohol–benzene, hot and cold water solubility and solubility in dilute alkali (1% NaOH)) of hazelnut husk and to evaluate its suitability to produce composite panels. For this study, particleboards were produced using hazelnut husk as an alternative raw material for the forest products industry. Two panel density levels (0.6 and 0.7 g/cm³) and three types of resins (urea-formaldehyde (UF), phenol formaldehyde (PF), melamine-formaldehyde (MUF)) were selected as treatments. The findings indicated that hazelnut husk waste is a valuable renewable natural resource for particleboard production and could be utilized as a substitute for wood in board production. Its shortcomings, such as higher water absorption and thickness swelling could easily be controlled by adding water repellent chemicals in production. The bending and the internal bond strength properties of the hazelnut husk boards produced met the requirement for the general purpose product standards (TS-EN 312-2) at 0.70 g/cm³ density.     

Occurrence of nematodes in benthic deposits

This paper describes a method which has been developed and found satisfactory for sampling and separation of nematodes in benthic deposits of shallow streams with sandy bottoms. A simple scoop is described for obtaining an undisturbed sample. A modification of the centrifugal flotation technique described was found more quantitative than other methods. A 3-min flotation at 2900 g in a sugar solution was followed by filtration of the supernatant through a 5μ membrane filter for separation. Enumeration was carried out after staining with eosin-Y dye. The method can safely be used to make a quantitative determination of the concentration of nematodes in benthic samples.

Nematodes were found to be present in all sections of the stream system investigated. The concentration of nematodes in water and benthic samples were significantly higher below the outfall of a waste treatment plant than above the outfall. The concentrations of nematodes in the benthos during the fall months were found to be about twice that observed during summer months. This was attributed to the more favorable temperatures during the fall. During the same period, the nematode concentration in the stream benthos did not bear any constant ratio to that in the water. The nematodes in the benthos were severely affected by high flows in the stream because of the erosive action of such high discharges. The concentration of nematodes in the benthos was observed to increase during low flows. The variation found in physical properties such as effective size and uniformity coefficient and chemical properties such as chemical oxygen demand, total nitrogen, and pH of the bottom material were found to have no direct relationship to the nematode concentration.     

Study of high performance autoclaved shell-aggregate from propylene oxide sludge

This study focuses on the comprehensive utilization of propylene oxide sludge (POS). High performance propylene oxide sludge aggregate (POSA), whose main hydrated phase is tobermorite, was prepared by the hydrothermal synthesis of POS and silica materials under the condition of 180 °C saturated steam. The factors affecting the performance of the aggregate were investigated systematically by orthogonal experiments, thus aggregate with cylinder compressive strength between 6.14 and 13.52 MPa, bulk density between 882 and 1163 kg/m³, apparent density between 1515 and 1916 kg/m³, 1 h water absorption rate between 4% and 14%, 24 h water absorption rate between 11% and 19%, the mass loss of freezing and thawing between 1.63% and 3.92% was achieved. By single-factor analysis, it was shown that cylinder compressive strength and specific strength of propylene oxide sludge shell-aggregate (POSS-A) increases by 21.3% and 13.9%, respectively, in contrast to the POSA with no shell. At the same time, 1 h water absorption rate and 24 h water absorption rate decreases by 57% and 20%, respectively. The compressive strength of the concrete with POSS-A as coarse aggregate reaches 80 MPa, which is 8.1% higher than that of the crushed stone concrete. In addition, the density gets lowered by 17%. The HVEP results of analysis of the aggregate imply that heavy metals are solidified inside aggregate and the POSA thus fabricated is non-hazardous for construction use.     

The role of nematodes in low rate percolating filter sewage treatment works

The contribution and role of bacterivore nematodes in energy flow in two low rate percolating filter works was calculated based on field sampling and laboratory studies of feeding rates and energy ingestion, growth, reproduction and respiration. At both sewage works energy flow values peaked in May and January corresponding to peaks in nematode density and biomass. Simplified energy flow diagrams related to time are presented expressed for a core extending from the bed surface to its bottom. Nematode ingestion in the filter-beds exercised a distinct effect on the bacterial community such that in order to maintain steady-state conditions a mean bacterial doubling time ranging from 31 to 291 h was necessary at Caton Effluent Treatment Works and 87–4460 h at Carnforth ETW. Localized grazing effects, especially in the upper filter regions, exercised even greater effects, where a doubling time of 4 h may have been required on occasions. Oxygen consumption attributable to nematodes ranged from 0.03 to 2.7% of total community respiration at the two treatment works, suggesting that in general the direct role of nematodes is relatively small and they exert their greatest effect by grazing on bacteria.     

Snow heterogeneity in Luleå, Sweden

Snow water equivalent (SWE) and snow covered area (SCA) are fundamental considerations when planning for snowmelt events. Depth, density and albedo measurements are used to demonstrate the spatial variability of SWE in the city of Luleå, Sweden. Undisturbed urban snow is similar to nearby rural snow (albedo 0.5–0.6, density 200–300 kg m⁻³) whereas ploughed snow piles have a wide range of characteristics (albedo < 0.3–0.5, density 250–700 kg m⁻³). Snow piles are located on permeable surfaces in suburbs and impervious surfaces where landuse is intense. Snowmelt runoff simulated assuming first a homogenous then a heterogeneous snowpack shows that the presence of piles can reduce the maximum volume of melt and extend the melt period.     

Thermo-environmental performance analysis of irreversible solid oxide fuel cell – Stirling heat engine

A hybrid, irreversible solid oxide fuel cell – Stirling heat engine system is taken into account. Thermoenvironmental criterion approach, which enables to evaluate environmental impact of any thermal cycle, is applied to the considered system for the first time. Power density, exergy density, thermoenvironmental function density, energy and exergy efficiencies are considered. Results are presented and discussed to determine optimum operating conditions. Some important results for the hybrid system are ordered: maximum power density is 7489.92 (A?m^?2), maximum energy and exergy efficiencies are 0.800 and 0.887, respectively, and finally, thermoenvironmental function density is 0.0276 (W?mpts^?1?m^?2).     

Assessing the risk posed to free-living soil nematodes by a genetically modified maize expressing the insecticidal Cry3Bb1 protein

Before pest-resistant genetically modified maize can be grown commercially, the risks for soil-beneficial, non-target organisms must be determined. Here, a tiered approach was used to assess the risk to free-living soil nematodes posed by maize genetically modified to express the insecticidal Cry3Bb1 protein (event Mon88017), which confers resistance towards western corn rootworm (Diabrotica virgifera; Coleoptera). The toxicity of purified Cry3Bb1 for the nematode Caenorhabditis elegans was determined using a bioassay and gene expression analysis. In addition, a soil toxicity test was used to assess the effects on C. elegans of rhizosphere soil obtained from plots of an experimental field grown with Mon88017, the near-isogenic cultivar, or either of two conventional cultivars. Finally, the indigenous nematode communities from the experimental field site with Mon88017 and from the control cultivars were analyzed. The results showed a dose-dependent inhibitory effect of Cry3Bb1 on the growth and reproduction of C. elegans, with EC50 values of 22.3 mg l⁻¹ and 7.9 mg l⁻¹, respectively. Moreover, Cry-protein-specific defense genes were found to be up-regulated in the presence of either Cry1Ab or Cry3Bb1. However, C. elegans was not affected by rhizosphere soils from Mon88017 compared to the control plots, due to the very low Cry3Bb1 concentrations, as indicated by quantitative analyses (< 1 ng g⁻¹ soil). Nematode abundance and diversity were essentially the same between the various maize cultivars. At the last sampling date, nematode genus composition in Bt-maize plots differed significantly from that in two of the three non-Bt cultivars, including the near-isogenic maize, but the shift in genus composition did not influence the composition of functional guilds within the nematode communities. In conclusion, the risk to free-living soil nematodes posed by Mon88017 cultivation can be regarded as low, as long as Cry3Bb1 concentrations in soil remain four orders of magnitude below the toxicity threshold.     

Electroflottation et desinfection simultanee d'eaux residuaires urbainesSimultaneous electroflotation and disinfection of sewage

This reports presents the results of a simultaneous electroflotation and disinfection sewage treatment, after chemical coagulation and flocculation and in the presence of chloride ions at various concentrations. Theoretical studies had shown that anodic oxidation of chloride ions gives hyperchlorites (for pH 7.5) together with (if sufficient potential is provided) oxygen. A dynamic study was thus achieved. It appeared that for a given chloride concentration the chlorine production linearly increases with the current density and depends on the organic load (COD) and oxidation potential of the effluent (Figs 6, 7 and 8). The performances of the process were studied in the continuous mode on a small pilot plant, after treatment of the effluent with ferric chloride and an organic polymer (Fig. 2). In all experiments current density and chloride concentration were raised (respectively 100, 200, 300 A m^?2 and from 300 to 3000 mg l^?1). The results obtained showed that solid-liquid separation was improved over static clarification for 2 h (Table 3) and the disinfection efficiency was equal or better than that obtained with gaseous chlorine (Table 4, Fig. 9). For example at a 900 mg l^?1 chloride concentration the three current density used give treated water containing less than 10³/100 ml total coliforms (initial concentration 4.7 · 10⁷/100 ml). These results have direct applications to the design of electroflotation units where a better plug flow should be sought. Moreover this process produces highly concentrated sludges. The utilization of ATP (Adenosine Triphosphate) as an indicator of the viability of a biomass showed that the process is applicable to activated sludges with recycling. The experimental conditions required for this application are still uncertain and require further study.     

改进一步法模型及TDR自适应方法研究

建立土体含水率和干密度与电磁参数间的经验模型是TDR技术在岩土工程中应用的关键。在原一步法模型基础上,分别建立了土体含水率、干密度与土体介电常数等电磁参数间新的经验关系模型,实现了干密度和含水率的解耦计算。分析了击实功、孔隙水电导率、温度等因素对新经验公式的影响。通过标定后,新经验公式计算的干密度相对偏差在±5%以内,含水率偏差在±0.02 g.g~(-1)以内。同时,提出了一种TDR自适应方法,可在现场无标定条件下实现土体干密度和含水率的快速高效测定。     

The entrainment of nutrients from below the thermocline in the coral sea into the great barrier reef lagoon via cook's passage

Cool, nitrate-enriched water is drawn into Cook's Passage by rapid inflowing tidal currents. The water is a mixture of surface Coral Sea water and subtropical lower water. At depths > 30 m, the range of the mean nitrate concentration for outflows, calculated from hourly measurements, was 0.25–0.8 μg 1⁻¹, and for inflows it was 1.0–1.5 μg 1⁻¹. The maximum values normally recorded were in the range 2.0–2.7 μg1⁻¹. The quantity of nitrate in the water column is not dependent solely on the tidal amplitude; undulations in the thermocline are believed to play a major role in determining how much enrichment takes place. In the 40 m water column examined, the nitrate concentration in outflowing waters appeared to be a function of the amount entrained on the previous incoming cycle, with a loss to the lagoon of approximately 16 mg under 1 m² of surface. The mean silicate concentrations in outflows and inflows were 32.0 ± 6.0 and 35.2 ± 4.6 μg 1⁻¹, respectively, with corresponding phosphate values of 4.5 ± 0.7 and 4.6 ± 0.9 μg 1⁻¹, respectively. Neither shows any distinctive relationship with tides.     

Electroflottation et desinfection simultanee d'eaux residuaires urbaines

This reports presents the results of a simultaneous electroflotation and disinfection sewage treatment, after chemical coagulation and flocculation and in the presence of chloride ions at various concentrations. Theoretical studies had shown that anodic oxidation of chloride ions gives hyperchlorites (for pH 7.5) together with (if sufficient potential is provided) oxygen. A dynamic study was thus achieved. It appeared that for a given chloride concentration the chlorine production linearly increases with the current density and depends on the organic load (COD) and oxidation potential of the effluent (Figs 6, 7 and 8). The performances of the process were studied in the continuous mode on a small pilot plant, after treatment of the effluent with ferric chloride and an organic polymer (Fig. 2). In all experiments current density and chloride concentration were raised (respectively 100, 200, 300 A m⁻² and from 300 to 3000 mg l⁻¹). The results obtained showed that solid-liquid separation was improved over static clarification for 2 h (Table 3) and the disinfection efficiency was equal or better than that obtained with gaseous chlorine (Table 4, Fig. 9). For example at a 900 mg l⁻¹ chloride concentration the three current density used give treated water containing less than 10³/100 ml total coliforms (initial concentration 4.7 · 10⁷/100 ml). These results have direct applications to the design of electroflotation units where a better plug flow should be sought. Moreover this process produces highly concentrated sludges. The utilization of ATP (Adenosine Triphosphate) as an indicator of the viability of a biomass showed that the process is applicable to activated sludges with recycling. The experimental conditions required for this application are still uncertain and require further study.