Water treatment control using the joint estimation outlier detection method

The loss of contaminated wastewater into the environment by leakage or other means is a serious problem. This problem is essentially the same as true of the loss of chemical reagents from a chemical production or purification process. The present article shows how the joint estimation method, an outlier detection method for time series analysis, can be used by a facility manager to deal with these problems.     

Support Vector Machine Modeling Using Particle Swarm Optimization Approach for the Retrieval of Atmospheric Ammonia Concentrations

This study was performed in order to improve the estimation accuracy of atmospheric ammonia (NH₃) concentration levels in the Greater Houston area during extended sampling periods. The approach is based on selecting the appropriate penalty coefficient C and kernel parameter σ ². These parameters directly influence the regression accuracy of the support vector machine (SVM) model. In this paper, two artificial intelligence techniques, particle swarm optimization (PSO) and a genetic algorithm (GA), were used to optimize the SVM model parameters. Data regarding meteorological variables (e.g., ambient temperature and wind direction) and the NH₃ concentration levels were employed to develop our two models. The simulation results indicate that both PSO-SVM and GA-SVM methods are effective tools to model the NH₃ concentration levels and can yield good prediction performance based on statistical evaluation criteria. PSO-SVM provides higher retrieval accuracy and faster running speed than GA-SVM. In addition, we used the PSO-SVM technique to estimate 17 drop-off NH₃ concentration values. We obtained forecasting results with good fitting characteristics to a measured curve. This proved that PSO-SVM is an effective method for estimating unavailable NH₃ concentration data at 3, 4, 5, and 6 parts per billion (ppb), respectively. A 4-ppb NH₃ concentration had the optimum prediction performance of the simulation results. These results showed that the selection of the set-point values is a significant factor in compensating for the atmospheric NH₃ dropout data with the PSO-SVM method. This modeling approach will be useful in the continuous assessment of NH₃ sensor discrete data sources.     

Impact of land disturbance on the fate of arsenical pesticides

Increasing development of historic farmlands raises questions regarding the fate of pesticides applied when these land were in cultivation. We quantified As and Pb budgets in field soils in two orchards where arsenical pesticides were applied in the early 20th century and a third uncontaminated control field. Sequential extractions and X-ray analyses also were used to determine mineral phases. In addition, we measured metal loads in drainages adjacent to the fields and in two common macroinvertebrate taxa within the wetland at the outlet of the drainages. We find that the applied As and Pb have undergone little vertical redistribution; concentrations of As and Pb in the top 25 cm of contaminated orchard soils are higher than in the uncontaminated control field. However, none of the applied lead arsenate (PbHAsO4) remains in its original mineral phase. Instead, the metals are now primarily adsorbed onto fine silt and clay-sized amorphous oxides and organic matter. Further, physical erosion associated with tilling and replanting appears to have mobilized the fine-particulate-bound As and Pb in one orchard. The remobilized metals are found in sediments in the stream channel draining the tilled orchard. It is unclear if the As and Pb transported sediments are biologically active; average macroinvertebrate metal burdens in the wetland are not elevated above those observed elsewhere in the region. However, little of the mobilized metals may have reached the wetland. These results demonstrate that land use change can significantly impact the retention of arsenical pesticides.     

Macroalgal Introductions by Hull Fouling on Recreational Vessels: Seaweeds and Sailors

Macroalgal invasions in coastal areas have been a growing concern during the past decade. The present study aimed to assess the role of hull fouling on recreational yachts as a vector for macroalgal introductions. Questionnaire and hull surveys were carried out in marinas in France and Spain. The questionnaires revealed that the majority of yacht owners are aware of seaweed introductions, usually undertake short range journeys, dry dock their boat at least once a year, and use antifouling paints. The hull survey showed that many in-service yachts were completely free of macroalgae. When present, fouling assemblages consisted mainly of one to two macroalgal species. The most commonly found species was the tolerant green seaweed Ulva flexuosa. Most of the other species found are also cosmopolitan and opportunistic. A few nonnative and potentially invasive Ceramiales (Rhodophyta) were found occasionally on in-service yachts. On the basis of the information gathered during interviews of yacht owners in the surveyed area, these occurrences are likely to be uncommon. However they can pose a significant risk of primary or secondary introductions of alien macroalgal species, especially in the light of the increase in yachting activities. With large numbers of recreational yachts and relatively rare occurrences of nonnative species on hulls, comprehensive screening programs do not seem justified or practical. The risks of transferring nonnative species may, however, be minimized by encouraging the behaviors that prevent fouling on hulls and by taking action against neglected boats before they can act as vectors.     

Application of an empirical transport model to simulate retention of nanocrystalline titanium dioxide in sand columns

Nanocrystalline titanium dioxide was injected into sand columns to simulate subsurface injection for creation of a permeable treatment barrier. Past usage of this material as an ex situ pilot scale treatment filter has shown that it has a high adsorption capacity for a number of heavy metals and therefore would be a good candidate for injection technology. Three suspension concentrations (50, 75 and 100 mg l(-1)) were pumped through packed sand columns at different flow velocities (3.0, 6.8 and 14.1 cm min(-1)). Little to no particles was detected in the effluent. Most of the nanoparticles remained in the sand columns, with an increasing then decreasing retained solids pattern. Application of a one-dimensional advection-dispersion flow model, that included two empirical kinetic terms to account for particle retention in the porous media, produced data fits that followed the general trend of the data, but did not truly capture the concentration maxima in the data sets. Discussion of these results highlights the limited ability of existing models to aid in predicting particle retention of non-ideal materials for engineering purposes.     

The primary aerobic biodegradation of biodiesel B20

We describe the primary aerobic biodegradation of a B20 fuel (20% soybean fatty acid methyl esters, 80% petroleum diesel) by unacclimated inocula from a rainwater detention pond. Biodegradation was rapid and essentially complete, with an overall median 'half-life', at approximately 100 ppm B20, of 6.8 days (n=34). Using purge-and-trap and extraction methodologies, both coupled to GC/MS, and hexachloroethane and hexachlorobenzene as conserved internal markers in the B20, we followed the biodegradation of total detectable material, 76 individual analytes and eight undifferentiated groups of isomers, and calculated their half-lives under these conditions. The fatty acid methyl esters, n-alkanes and iso-alkanes, and simple and alkylated aromatic compounds were the most readily degraded compounds, followed by the naphthenes. The last (identified) compounds to be degraded were ethylalkanes, trisubstituted cyclohexanes and decalins, but even these disappeared with an apparent 'half-life' of <30 days.     

How good micro/macro ergonomics may improve resilience,but not necessarily safety

ContextProfessional sea fishing is among the world’s most variable (non-standardized) and dangerous sectors of activity. Because of this, it provides a remarkable model to study the complex links existing between resilience and safety. Paradoxically, even if the huge risks being run cause many shipwrecks (low safety level), studies show that these sailors avoid an even greater number of accidents thanks to their exceptional skill and know-how (remarkable resilience level). This article examines several ways of improving safety in an activity of this type.MethodTwo intervention strategies are tested: (i) a micro-ergonomics strategy offering conduct assistance guidelines based on accident analyses of the most serious and frequent causes (collisions while fishing); (ii) a macro-ergonomics strategy comparing the safety level of large firms having committed to a Total Quality approach, to that of smaller companies, often privately owned.ResultNeither of the two strategies works out as expected. The micro-ergonomics anti-collision assistance strategy is misused towards an increase of the fishing objective; the macro-ergonomics strategy is even more surprising: the largest firms suffer from a smaller number of shipwrecks, but a much greater number of work-related injuries; the strategy simply results in a minor shift of the sacrificial decision between performance and safety (loss of men vs. loss of vessels), while maintaining the same priority for financial performance.DiscussionThe article submits a simple modeling of the relationship between resilience and safety, and discusses the choice of strategies for safety-improving interventions, taking into account the system’s financial performance and the legal pressure to which it is subjected.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

Bestimmung von Mineralölkohlenwasserstoffen in Bodenproben mit Hilfe der Dünnschichtchromatographie

A thin-layer chromatographic method for the determination of mineral oil hydrocarbons (aliphatic compounds and naphtenes) of medium and low volatility in soil samples is presented which is based on their separation and quantitative determination. The extraction of the soil samples is effected by means of an n-hexane-acetone mixture (10∶1) supported by ultrasonics. The evaluation can be made visually or densitometrically by means of a thin-layer scanner. The applicability and restrictions of the method are shown. The advantage of the method lies in its low requirements pertaining to apparatus and chemicals, as well as in its rapidness which makes it suitable for quick in-situ analyses as, for example, for the assessment of the mineral oil content of a contaminated site.