Degradation of the non-ionic surfactant dobanol 45-7 by activated sludge

The degradation of Dobanol 45-7 by activated sludge was examined. The surfactant was used at high concentrations (500 mg 1⁻¹) both to simulate an overloading situation at a municipal sludge works, such as could result from an accidental spillage, and to facilitate the isolation of any transient products formed on degradation. Analyses by total organic carbon (TOC) measurement, thinlayer chromatography (TLC) and gas-liquid chromatography (GLC) of both trimethyl silyl ether derivatives and HBr fission products indicated that degradation was both rapid and complete; no persistent metabolites were detected. The data presented suggested that the surfactant was initially degraded by removal of the alkyl moiety giving rise to a polyglycol-like product which was subsequently degraded via an acidic intermediate(s).     

Bacterial treatment effectiveness of point-of-use ceramic water filters

Laboratory experiments were conducted on six point-of-use (POU) ceramic water filters that were manufactured in Nicaragua; two filters were used by families for ca. 4 years and the other filters had limited prior use in our lab. Water spiked with ca. 10⁶ CFU/mL of Escherichia coli was dosed to the filters. Initial disinfection efficiencies ranged from 3 - 4.5 log, but the treatment efficiency decreased with subsequent batches of spiked water. Silver concentrations in the effluent water ranged from 0.04 - 1.75 ppb. Subsequent experiments that utilized feed water without a bacterial spike yielded 10³-10⁵ CFU/mL bacteria in the effluent. Immediately after recoating four of the filters with a colloidal silver solution, the effluent silver concentrations increased to 36 - 45 ppb and bacterial disinfection efficiencies were 3.8-4.5 log. The treatment effectiveness decreased to 0.2 - 2.5 log after loading multiple batches of highly contaminated water. In subsequent loading of clean water, the effluent water contained <20-41 CFU/mL in two of the filters. This indicates that the silver had some benefit to reducing bacterial contamination by the filter. In general these POU filters were found to be effective, but showed loss of effectiveness with time and indicated a release of microbes into subsequent volumes of water passed through the system.     

Microbiological aspects of fish grown in treated wastewater

Tilapia, common carp and silver carp were reared in treated domestic wastewater. The most sensitive to this environment was the silver carp, followed by common carp and tilapia. In healthy clean fish, bacteria were not found in the blood or the muscles. They were present in small numbers in various organs and in concentrations of 10⁶–10⁷ g⁻¹ in the digestive tract content. In fish exposed to treated wastewater for the entire growing period, bacteria were found in the muscles. The number of bacteria recovered from various organs ranged between 10⁴–10⁶ g⁻¹ and their concentration in the digestive tract content was 10⁸–10⁹ g⁻¹. The number of bacteria in the pond water determined the presence and concentration of bacteria in the fish. The number of bacteria that caused their appearance in the muscles of fish has been named the “threshold concentration”. Considering the public health aspects, fish can be reared in treated wastewater provided the bacteriological quality of the water is compatible with the “threshold concentration” levels of the fish grown in the ponds. The suitability of E. coli (fecal coliform bacteria) as indicators for the bacteriological quality of fish grown in wastewater-fed ponds is examined.     

Quantitative in situ monitoring of organohalogen compounds in domestic sewage resulting from the use of hypochlorite bleach

A field monitoring program was carried out on the sewage of five large apartment blocks in the city of Parma, Italy, to verify under realistic conditions existing laboratory data and model calculations on organohalogen formation by domestic hypochlorite (NaOCl) bleach usage. The average adsorbable organic halogens (AOX) level was determined for three distinct experimental phases: an “undisturbed period,” a “no bleach period,” and a “controlled bleach usage period.” The study involved participation of the site inhabitants in the second and third phases.In line with what could be predicted from the hypochlorite chemistry, an effect of the use of hypochlorite bleach on the AOX concentration in domestic sewage was detected. In a laboratory simulation conducted in parallel with the field study, the degree of NaOCl-to-AOX conversion ranged from 0.75 to 2.25% (w/w). The degree of conversion in the field study itself was of the order of 1.5% (or 0.075% when expressed for a typical bleach product containing 5% NaOCl). Under the specific conditions of the site, the difference in average AOX concentration in sewage between the “no bleach” and the “undisturbed” bleach use period was of the order of 37 μg·1⁻¹ (P < 0.05). The average bleach-related AOX emission at the study site was around 7 mg·(inhabitant·day)⁻¹. Overall, these figures correspond well with existing literature data. Linking the measured amounts of AOX with available ecotoxicity data for treated domestic effluents and their organohalogen constituents, it can be considered unlikely that the organohalogens formed by domestic bleaching will exert or trigger any adverse environmental effect.     

Biodegradability and toxicity of sulphonate-based surfactants in aerobic and anaerobic aquatic environments

Four types of commonly used sulphonate-based surfactants (alkane sulphonates, alpha-olefin sulphonates, sulphosuccinates and methyl ester sulphonates) were tested for their aerobic and anaerobic biodegradability as well as for their toxicity to Daphnia magna and Photobacterium phosphoreum to assess the effect of the surfactant structure on those properties. Aerobic biodegradation was evaluated by means of the CO₂ headspace test and anaerobic biodegradation was assessed by a method based on the ECETOC test. All the surfactants tested were readily biodegraded under aerobic conditions. No clear effect of the surfactant structures on the toxicity to the aquatic organisms tested was found. The most significant differences in the surfactants studied were observed in their behaviour under anaerobic conditions. Alkane sulphonates, alpha-olefin sulphonates and methyl ester sulphonates were not mineralized in lab anaerobic digesters despite the fact that the last one showed a certain degree of primary degradation. Nevertheless, these surfactants did not significantly inhibit methanogenic activity at concentrations up to 15 g surfactant/kg dry sludge, a concentration that is much higher than the expected concentrations of these surfactants in real anaerobic digesters. Sulphosuccinates showed a high level of primary biodegradation in anaerobic conditions. However, linear alkyl sulphosuccinates were completely mineralized whereas branched alkyl sulphosuccinates achieved percentages of ultimate biodegradation ≤50%.     

Adsorption of non-ionic surfactants on activated carbon and mineral clay

A series of non-ionic surfactants of nonyl-phenol ethoxylates, with n = 4?23;0 ethylene oxide groups and dinonyl-phenol ethoxylate were studied in dilute aqueous solution. Their removal efficiencies and mechanisms by adsorption on powdered and granular activated carbon and on Na-montmorillonite clay were investigated. The powdered activated carbon proved to be the most efficient with 94–100% non-ionic surfactants removal by addition of 40–80 mg activated carbon.Various models of adsorption isotherms such as Langmuir, BET and S-type were used to determine Q⁴, the limiting adsorption capacity. The relationships between Q^o and parameters affecting the adsorption of non-ionic surfactants such as n, HLB and CMC were determined. The cross-sectional area σ₀ occupied by surfactant molecules on the adsorbent was calculated. Adsorption has been proven to be a potential advanced physicochemical treatment method for the effective removal of non-ionic surfactants present in effluents intended for reuse.     

Essais d'aerateurs: Enseignements tires de 500 essais en eau claire effectues dans 200 stations d'epuration differentes—I. MethodologieTests on aerators: Conclusions drawn from 500 clean water tests conducted in 200 different sewage treatment plants—I. Test procedure

Aeration represents the main part of energy consumption in the activated sludge process and the evaluation of aeration systems efficiency is becoming more important, especially as energy cost increases. Since 1972, CEMAGREF teams have carried out more than 500 non-steady state clean water tests in sewage treatment plants. The first aim of these measurements was to compare the results collected in plants with those predicted by manufacturers.The distribution of the different types of aerators tested in the field by the CEMAGREF is given in Table 1. All tests are conducted using tap water under non-steady state conditions: the initial dissolved oxygen (DO) level is brought down to zero by adding cobalt chloride as catalyst and sodium sulfite. When all the sodium sulfite has been used, the increase in water dissolved oxygen content is monitored vs time in various places in the tank by means of membraned probes.The graphical procedure used for estimating the oxygen transfer coefficient (K_La) is shown in Fig. 1; this procedure is usually called “log deficit method”. The results are expressed for “standard conditions” (θ = 10°C; P = 760 mm Hg). The influence of temperature on oxygenation capacity is illustrated in Fig. 2.The water quality parameters that may affect oxygen transfer are investigated: it appears that only the presence of surfactants, flocculated suspended solids, or high salinity (conductivity > 1500 μS cm^?1—Table 2) are liable to have any appreciable effect on oxygen transfer. The unflocculated SS, pH and alkalinity have no effect on oxygenation results in the common range of values occurring in the tests (Table 3).Authors differ about the operational procedure in non-steady state clean water test. After 7 years' field-measurements the CEMAGREF teams have developed their own recommendations about test procedures; their main conclusions are the following:Dissolved oxygen analysis: the differences observed between the results ($\text{K}{}_{\mathrm{L}}\text{a}$) obtained simultaneously by Winkler titration of piped samples and those from in-tank probes never exceed 4% (Table 4). Reliable dissolved oxygen probes are suitable for accurate measurements of oxygen transfer.The number of sampling points should be no smaller than three for aeration tanks with a volume below or equal to 500 m³. It should be recommended to add one sampling point for every additional 500 m³.Location of sampling points requires attention. Differences may appear according to the locations of probes in the basin (Tables 5, 6 and 7).Sulfite pre-dissolution has no influence on results and should be avoided whenever possible.     

Impact of microbial <Emphasis Type="Italic">Nocardia vaccinii</Emphasis> IMB B-7405 surfactants on oil destruction in water

The degradation degree of oil and complex oil pollutions with heavy metals in water in the presence of microbial Nocardia vaccinii IMB B-7405 surfactants has been studied. The destruction of oil in water (at concentrations of 2.6–6.0 g/dm³) 25–30 days after the treatment with post-fermentative culture liquid (5–10 vol %) containing the surfactants amounted to 76–94%.     

A method of reducing drag and fluctuating side force on bluff bodies

Measurements have been made of the forces imposed on typical two-dimensional bluff bodies with a small circular cylinder (here called a “rod”) placed upstream on the stagnation line. In most cases, the interaction was beneficial in that the drag of the overall system was lower with the rod than without it. Fluctuating side forces due to vortex shedding from the main body were also reduced for most rod positions and diameters.Three two-dimensional bluff bodies were investigated: a flat plate, a square and a circular cylinder. Reynolds numbers were in the range of 1 × 10⁴ to 7 × 10⁴.The measured overall drag coefficient at various rod spacing showed a discontinuous “jump” at some critical “jump” spacing. This change corresponded to the elimination of the usual single stagnation point on the bluff body centre line and the appearance of two stagnation points symmetrically placed, close to the lateral edges of the body.Significant drag reductions were obtained for all bluff body shapes when a front rod was located near the “jump” spacing. The fluctuating side force on the circular cylinder was reduced by the rod at high Re. On the square cylinder, the reduction in fluctuating side force was large (up to 90%) for any Re and rod size investigated.     

Experimental investigation of the aerodynamic stability of the “Endless Column”, Romania

Wind tunnel tests have been performed on several models of the “Endless Column”, a 30 m tall sculpture, created by C. Brancusi in 1938. In spite of its slenderness, the Column, located in Targul Jiu, Romania, has shown a great stability against wind. In order to clarify if the symmetric, original shape has influence upon its stability, we have carried out tests on section models of “Endless Column” shape (EC models) and square shape (SQ models), of various Sc numbers. Across-wind response was determined in smooth flow for wind speeds in wind tunnel of 1–10 m/s (Re=4000–46,000) for angles of attack 0°, 10° and 45°. Furthermore, an aerolastic full model was created and tests under smooth and turbulent flow conditions were performed for angles of attack between 0° and 45°. For low wind speeds, in the area of vortex-induced vibrations, the EC models had similar response with the SQ models; however, for higher wind speeds the EC models proved to be more stable. Based on measurements of aerodynamic drag and lift coefficients and by a verification of Glauert den Hartog criterion, it could be concluded that is a very low possibility for EC model to encounter galloping; for extremely high wind speeds though, this might not be impossible.     

Free nitrous acid inhibition on the aerobic metabolism of poly-phosphate accumulating organisms

In full-scale wastewater treatment systems, phosphorus removal typically occurs together with nitrogen removal. Nitrite, an intermediate of both the nitrification and denitrification processes, can accumulate in the reactor. The inhibitory effect of nitrite/free nitrous acid (FNA) on the aerobic metabolism of poly-phosphate accumulating organisms (PAOs) is investigated. A culture highly enriched (90 ± 5%) in Candidatus “Accummulibacter phosphatis”, a well-known PAO, was used to perform a series of batch experiments at various nitrite and pH levels. FNA was found to inhibit all key aerobic metabolic processes performed by PAOs, namely PHA oxidation, phosphate uptake, glycogen replenishment and growth. The inhibitory effect on the anabolic processes (growth, phosphate uptake and glycogen production) was much stronger than that on the catabolic processes (PHA oxidation). 50% inhibition on all anabolic processes occurred at FNA concentrations of approximately 0.5 × 10^?3 mg HNO₂–N/L (equivalent to 2.0 mg NO₂^?–N/L at pH 7.0), while full inhibition occurred at FNA concentrations of approximately 6.0 × 10^?3 mg HNO₂–N. These concentrations could be found in full-scale wastewater treatment systems that achieve nitrogen removal via the nitrite pathway. In comparison, PHA oxidation remained at 40–50% of the highest rate at FNA concentrations in the range 2.0 × 10^?3–10.0 × 10^?3 mg HNO₂–N/L. Interestingly, PAOs were able to reduce nitrite under aerobic conditions (DO ≈ 3 mg/L), with the rate increasing substantially with the FNA concentration. The inhibition on phosphate uptake was found to be reversible.     

Strain Rate Dependency of Cohesive Soils in Consolidation Settlement

It has been revealed from the long term consolidation test that the e-logp relation is linearly shifted with decrease in the strain rate in logarithm scale. The minimum strain rate measured by the conventional long term consolidation test is at most in the order of 10^-9s^-1. Question arises whether such a shift of the e-logp relation continues at even the infinite small strain rate, for example, smaller than 10^-9s^-1. To investigate the strain rate dependency of cohesive soil, the relaxation test was carried out for Osaka Pleistocene clays. It may be considered that in relaxation test, recoverable strain decreases due to decrease in acting pressure, and the irrecoverable strain equally increases, because the total strain remains constant. In this paper, assuming that the isotaches model can be applied to the irrecoverable strain, the strain rate dependency at very small strain rate was obtained from a series of relaxation tests. In this investigation the “strain rate dependency ratio” (SRDR) is defined as the ratio of the stress in the same &epsilon; or e under the objective strain rate, based on the strain rate of 3.3×10^-6s^-1. It is revealed that the SRDR at infinite small strain rate is about 0.7.     

Rapid measurement of suspended C,N, and P from Precambrian Shield Lakes using Near-infrared Reflectance Spectroscopy

Rapid (<2 min), simultaneous, non-chemical, non-destructive, cost-efficient measurement of the C, N, and P concentrations in suspended, particulate matter in water from lakes of varying trophic status, pH, and extent of metal contamination was attempted by the use of near-infrared reflectance spectroscopy (NIRS). This technique, widely used in the agricultural, food, pharmaceutical, petrochemical, and textile industries, is being explored for its applications to aquatic and environmental sciences. Suspended matter from lake water (10–100 ml) was collected on 2.5 cm dia. G/FC glass fibre filters so that filters bore 10.5–109.2 μg C, 0.8–18.9 μg N, and 0.09-2.67 μg P per filter. Filters were oven-dried and scanned with an NIRSystems 6500 near-infrared spectrophotometer. The spectral data were treated by multiple linear regression analysis to develop mathematical relationships (calibrations) between absorbance at particular wavelengths and amounts of C, N, and P determined by conventional chemical analytical methods. These calibrations were used to predict C, N, and P from an independent set of spectra. Agreement between these NIRS-predicted values and their chemical values was generally greater than 0.9 for C, N, and P (r² from 0.88 to 0.97).     

Effects of Water Content Distribution on Hydraulic Conductivity of Prehydrated GCLS against Calcium Chloride Solutions

When geosynthetic clay liners (GCLs) are applied as bottom liners at waste containment facilities, they are naturally prehydrated by absorbing moisture in the underlying base layers. In order to evaluate the effects of cations contained in waste leachates, this study investigated the effects of the water content distribution of the GCLs prehydrated with actual soils on their hydraulic conductivities against CaCl₂ solutions. The “prehydration tests”, which were conducted prior to the hydraulic conductivity tests, showed that the water content distribution of the prehydrated GCLs depends on the properties of the GCLs and the base layers. In particular, drastic differences between GCLs with powdered bentonite and GCLs with granular bentonite were observed in the prehydration water content and its distribution. Prehydrated GCLs with powdered bentonite had a higher water content and a more homogenous distribution than those with granular bentonite. The hydraulic conductivity tests showed that most of the prehydrated GCLs exhibit a low hydraulic conductivity of k?1.0×10^-8 cm/s against CaCl₂ solutions with 0.1-0.5 M. However, GCLs with granular bentonite may be difficult to homogeneously prehydrate and exhibit an unstable hydraulic conductivity, which varies from k=2.9×10^-9 cm/s to k=1.5×10^-6 cm/s. The homogeneity of the water content distribution has been considered an important factor to obtain a required barrier performance under prehydration conditions, which are naturally generated in actual sites.     

Isolation of Yersinia from surface water: Comparative study of three selective media

Isolation of Yersinia was undertaken on three media from surface water of the Moselle River. Samples collected over an 8-month period were examined with Y-M agar, CAL agar and “Y” medium. Out of 48 water samples, 33.3% were positive. The isolation frequency with Y-M agar (27%) was significantly higher than with CAL agar of “Y” medium (χ² = 11.2; 0.001 < P < 0.01). Furthermore, Y-M agar exhibited a wide diversity of species; Y. enterocolitica, Y. frederiksenii, Y. kristensenii and Y. intermedia were isolated. In addition, the aerobic cold-enrichment technique without culture broth appears adequate for Yersinia isolation.     

The panopticon prison as a “social condenser”: The study of the project for De Koepel prison by Rem Koolhaas/OMA (1979–1988)

Rem Koolhaas/OMA carried out the study for De Koepel prison throughout a decade (1979–1988). However, only its initial stages (1979–1980) were disclosed and have been investigated. The hypothesis presented in this article suggests that Koolhaas implemented his —then— recent thesis present in Delirious New York (1978) on “life in the metropolis” and the “Culture of Congestion” in the conception and design of this project. Thus, this article has the aim of examining —by means of the documents compelling the entire period of the study— how the project suggested transforming the domesticity of De Koepel prison into a “social condenser” of the contemporary metropolis. By doing so, it makes it possible to consider the role of this project within the first decade of Koolhaas' career as an architect (1978–1989), and to establish that Delirious New York is, in fact, the theory on which it was based on when first conceived. This project anticipated the strategy and the methodology he implemented, at a later time, in other projects, offering a different perspective. On this occasion, this diagrammatic investigation took place in Bentham's Panopticon; reason why, he was then able to develop the reflections on heterotopias and prisons carried out by Foucault.     

A comment to “Assessment of temperature gradient effects on moisture transfer through thermogradient coefficient”

In their recent paper in Building Simulation (Trabelsi et al. (2012), Building Simulation, 5: 107–115), “Assessment of temperature gradient effects on moisture transfer through thermogradient coefficient”, Trabelsi et al. introduce their assertions on “the occurrence of significant thermal diffusion”. In this comment, the premises and outcomes of their analysis are challenged, based on my own recent paper on that same topic (Janssen (2011), “Thermal diffusion of water vapour in porous materials: Fact or fiction?” International Journal of Heat and Mass Transfer, 54: 1548–1562). Firstly Trabelsi et al.’s physical model and measurement methodology are critiqued, partially based on their own measured results. Reinterpretation of their data indicates that no consistent nor significant thermal diffusion can be found, confirming vapour pressure as sole significant transport potential for diffusion. This suggests that their physical model, built upon vapour density and temperature, is physically confusing and needlessly complicated. The model additionally requires a thermogradient coefficient, the measurement of which is complex and unreliable. A physical model for vapour diffusion based on vapour pressure, making use of the easy to measure vapour permeability, is thus pragmatically and fundamentally preferable. The comment finally ends by disputing Trabelsi et al.’s findings on the impact of thermal diffusion on moisture buffering: it is argued that they are practically and fundamentally faulty.     

Experimental Characterisation of the Fire Behaviour of Thermal Insulation Materials for a Performance-Based Design Methodology

A novel performance-based methodology for the quantitative fire safe design of building assemblies including insulation materials has recently been proposed. This approach is based on the definition of suitable thermal barriers in order to control the fire hazards imposed by the insulation. Under this framework, the concept of “critical temperature” has been used to define an initiating failure criterion for the insulation, so as to ensure there will be no significant contribution to the fire nor generation of hazardous gas effluents. This paper proposes a methodology to evaluate this “critical temperature” using as examples some of the most common insulation materials used for buildings in the EU market, i.e. rigid polyisocyanurate foam, rigid phenolic foam, rigid expanded polystyrene foam and low density flexible stone wool. A characterisation of these materials, based on a series of ad-hoc Cone Calorimeter and thermo-gravimetric experiments, serves to establish the rationale behind the quantification of the critical temperature. The temperature of the main peak of pyrolysis, obtained from differential thermo-gravimetric analysis under a nitrogen atmosphere at low heating rates, is proposed as the “critical temperature” for materials that do not significantly shrink and melt, i.e. charring insulation materials. For materials with shrinking and melting behaviour it is suggested that the melting point could be used as “critical temperature”. Conservative values of “critical temperature” proposed are 300°C for polyisocyanurate, 425°C for phenolic foam and 240°C for expanded polystyrene. The concept of a “critical temperature” for the low density stone wool is examined in the same manner and found to be non-applicable due to the inability to promote a flammable mixture. Additionally, thermal inertia values required for the performance-based methodology are obtained for PIR and PF using a novel approach, providing thermal inertia values within the range 4.5 to 6.5 × 10³ W² s K^?2 m^?4.     

Lead concentration profiles in lead-210 dated Lake Ontario sediment cores

Lead concentrations were measured in sediment cores from four sites distributed among the three major sedimentary basins — Niagara, Mississauga and Rochester — of Lake Ontario for which sedimentation rates had been previously determined by ²¹⁰Pb dating.Around 90% of the total lead present in fine-grained surface sediments was removed by CH₃CO₂H/NH₂OH · HCl leaching, concentrations ranging from 137 μg/g in surface sections to a constant background of 12–13 μg/g at unpolluted depths. Lead-210 dating indicated that increases in lead concentrations commenced ca. 1850–1875 with 5, 10, 35 and 50% of the total “excess” lead inventory in the sediment column being assigned to the pre-1900 period and successive 25-year intervals during the 20th Century, respectively. Anthropogenic inputs of lead from such sources as the combustion of leaded gasoline and coal are responsible for these increases.About 10 μg/g lead remained in the sediment residue after leaching. The total natural lead flux to the sediments ranged from 0.4–1.3 μg/cm²/yr while “excess” lead of anthropogenic origin varied from 1.2–6.7 μg/cm²/yr and totalled 0.5–1.5 g/m² at the four sites.Various potential modes of introduction of anthropogenic lead and of ²¹⁰Pb to the lake are considered in conjunction with the ratio of Pb/²¹⁰Pb fluxes to the sediment.     

Modeling the viral load dependence of residence times of virus-laden droplets from COVID-19-infected subjects in indoor environments

In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus-laden droplets (termed as “virusol”) (Anand and Mayya, 2020). Herein we develop the theory of residence time of the virusols, as contrasted with complete droplet system in indoor air using a comprehensive “Falling-to-Mixing-Plate-out” model that considers all the important processes namely, indoor dispersion of the emitted puff, droplet evaporation, gravitational settling, and plate out mechanisms at indoor surfaces. This model fills the existing gap between Wells falling drop model (Wells, 1934) and the stirred chamber models (Lai and Nazarofff, 2000). The analytical solutions are obtained for both 1-D and 3-D problems for non-evaporating falling droplets, used mainly for benchmarking the numerical formulation. The effect of various parameters is examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from about 100 to 150 s at low viral loads (<10⁴/ml) to about 1100–1250 s at high viral loads (>10¹¹/ml). The implications are discussed.