Sizing and Costing of Electrostatic Precipitators

This is the second of a two-part article that reviews electrostatic precipitation theory, presents size estimating methods, and gives costing procedures for a variety of electrostatic precipitator (ESP) types and sizes. Part I of the article, which appeared in the April 1988 issue of JAPCA, discussed theory and sizing; this part presents costing. Information is given for estimating total capital investment including separate costs for the bare ESP (five types) and auxiliaries. Factors are given for installation and for indirect costs. Direct and indirect annual costs are discussed. An example problem is given.     

Evaluation of the best compromise between the urban air quality monitoring resolution by diffusive sampling and resource requirements

The need to collect data representative of overall urban pollution is all-important in order to monitor the population exposure. High spatial resolution monitoring using diffusive samplers allows studying of the urban pollutant distribution, thus enabling deeper investigation of their generation and diffusion mechanisms. Nevertheless, such a monitoring campaign has a certain cost. In this study we point out how to find the best compromise between the number of necessary measurements and the affordable costs for monitoring campaigns. We also describe an innovative method for the proper design of a fixed urban monitoring network by means of preliminary high spatial resolution campaigns using diffusive samplers. Four European capital cities (Dublin, Madrid, Paris and Rome) were monitored six times, each time for seven days. Benzene, toluene, ethylbenzene, xylenes (BTEX) and NO(2) concentrations were measured at 146 sites in Dublin, 293 in Madrid, 339 in Paris and 290 in Rome. Multiscale grids have been drawn which ranged in mesh size from 500 m to 2 km. The statistical processing of data produced a twofold result: the creation of isoconcentration maps with geostatistical procedures, and an algorithm aimed at locating the minimum number of sampling sites where the fixed monitoring stations should be placed. Average urban levels estimated on the basis of these selected sites differ by less than 8% from those calculated on the whole populations of the sampled points. The aim of this work is to investigate how far the resolution of a monitoring campaign of urban pollution by diffusive sampling can be reduced, thus making the monitoring less expensive in terms of human and financial resources, while preserving the same quality of the results that could be achieved with a higher resolution. We found that there is no significant loss of information when the resolution of the monitoring grid for BTEX is lowered to a mesh size of 1.85 km, that is a sampling site each 3.4 km(2), and that the minimum number of sampling sites to be used is N = 0.29 A, where A is the urban surface to be monitored (in km(2)). As the spatial distribution of NO(2) is less sensitive to the distance from the emission source than that of BTEX, this relationship could be retained as a valid lower limit for the mesh grid size also for NO(2) monitoring.     

Generating Synthetic Rainfall on Various Timescales—Daily, Monthly and Yearly

The main objective of this paper is to present a model for generating synthetic rainfall totals on various timescales to be applicable for a variety of uses. Many large-scale ecological and water resource models require daily, monthly and yearly rainfall data as input to the model. As historical data provides only one realisation, synthetic generated rainfall totals are needed to assess the impact of rainfall variability on water resources systems (Srikanthan, In: MODSIM2005, Melbourne, Dec. 2005, pp. 1915–1921, 2005). Thus, our preferred model should simulate rainfall for yearly, monthly and daily periods. We believe that, for water supply issues, no higher resolution is needed, although higher resolution would be useful in models designed to measure the risk of local flooding. The critical factors are daily, monthly and yearly totals and daily, monthly and yearly variation. A model for generating yearly totals will be described using traditional time series methods. This model, along with a similarly constructed daily generation model by Piantadosi et al. (A New Model for Correlated Daily Rainfall, 2008), will be cascaded to start with a synthetic yearly total, then generate a synthetic sequence of monthly totals (through selection from a large number of realisations) that match the yearly total, and subsequently perform a similar operation for sequences of daily totals to match the required monthly totals. We present a new model for the generation of synthetic monthly rainfall data, which we demonstrate for Parafield in Adelaide, South Australia. The rainfall for each month of the year is modelled as a non-negative random variable from a mixed distribution with either a zero outcome or a strictly positive outcome. We use maximum likelihood to find parameters for both the probability of a zero outcome and the gamma distribution that best matches the observed probability density for the strictly positive outcomes. We describe a new model that generates correlated monthly rainfall totals using a diagonal band copula with a single parameter to generate lag-1 correlated random numbers. Our model preserves the marginal monthly distributions and, hence, also preserves the monthly and yearly means. We show that, for Parafield, the correlation between rainfall totals for successive months is not significant, and so, it is reasonable to assume independence. This is, however, not true for daily rainfall. We describe a new model that generates correlated daily rainfall totals using a diagonal band copula with a single parameter to generate lag-1 correlated random numbers. This is an extended version of a paper presented at the 17th Biennial Congress on Modelling and Simulation, Christchurch, New Zealand, December 2007.     

An Application of the Pump-to-Fill Policy for Management of Urban Stormwater

We consider the management of urban stormwater in two connected dams. Stormwater generated by local rainfall flows into a capture dam and is subsequently pumped into a similar sized holding dam. We assume random gross inflow and constant demand. If we wish to minimise overflow from the system then the optimal management policy is to pump as much water as possible each day from the capture dam to the holding dam without allowing the holding dam to overflow. We shall refer to this policy as the pump-to-fill policy. The model is based on the Parafield stormwater management system in the City of Salisbury (CoS) but assumes constant demand instead of level dependent outflow. If there is insufficient water in the holding dam to meet the desired daily demand then all water in the holding dam is used and the shortfall is obtained from other sources. CoS, in suburban Adelaide in South Australia, is recognised in local government circles as a world leader in urban stormwater management. The water is supplied to local industry to replace regular mains water and is also used to restore and maintain urban wetlands. In mathematical terms the pump-to-fill policy defines a Markov chain with a large transition matrix and a characteristic regular block structure. We use specialised Matrix Analytic Methods to decompose the event space and find simplified equations for the steady state probability vector. In this way we enable an elementary solution procedure which we illustrate by solving the modified Parafield problem. The optimal nature of the pump-to-fill policy is established in a recent paper by Pearce et al. (JIMO 3(2):313–320, 2007). The purpose of the current study is to find optimal management policies for urban stormwater systems. Work supported by the Australian Research Council.     

Role of soil sorption and microbial degradation on dissipation of mesotrione in plant-available soil water

Mesotrione is a carotenoid biosynthesis-inhibiting herbicide labeled for pre-emergence and postemergence weed control in corn production. Understanding the factors that influence the dissipation of mesotrione in soil and in the plant-available water (PAW) is important for the environmental fate assessment and optimal weed management practices. The present research investigated the role of soil properties and microbial activities on the interrelated sorption and degradation processes of mesotrione in four soils by direct measurements of PAW. We found that mesotrione bound to the soils time dependently, with approximately 14 d to reach equilibrium. The 24-h batch-slurry equilibrium experiments provided the sorption partition coefficient ranging from 0.26 to 3.53 L kg(-1), depending on soil organic carbon and pH. The dissipation of mesotrione in the soil-bound phase was primarily attributed to desorption to the PAW. Degradation in the PAW was rapid and primarily dependent on microbial actions, with half-degradation time (DT(50)) <3 d in all four soils tested. The rapid degradation in the PAW became rate limited by sorption as more available molecules were depleted in the soil pore water, resulting in a more slowed overall process for the total soil-water system (DT(50) <26 d). The dissipation of mesotrione in the PAW was due to microbial metabolism and time-dependent sorption to the soils. A coupled kinetics model calibrated with the data from the laboratory centrifugation technique provided an effective approach to investigate the interrelated processes of sorption and degradation in realistic soil moisture conditions.     

An Evaluation of Multiple Objective Decision Support Weighting Techniques in Natural Resource Management

Multiple objective decision support (MODS) is a structured framework for evaluating decision alternatives against multiple, and often conflicting, criteria. Its ability to handle complex trade-offs in a variety of quantitative and qualitative units gives it much potential in the field of natural resource management (NRM). A key component of MODS is the process used to obtain information from decision makers on the relative importance of evaluative criteria. Ranking algorithms then use this information to determine the relative value of each decision alternative. This paper explores how practising community based NRM decision makers respond to five generic methods for weighting the criteria. It presents a study in which 55 decision makers throughout five regions in Queensland, Australia, applied MODS to evaluate environmental projects seeking funding under the Australian Natural Heritage Trust. Weighting methods applied include fixed point scoring, rating, ordinal ranking, a graphical method and paired comparisons. Decision makers evaluated each weighting method in terms of ease of use and of how much it helped clarify the decision problem. Results show that decision makers felt uncomfortable applying fixed point scoring and generally preferred to express their preferences through ordinal ranking. This has implications for the types of ranking algorithms that can be applied to evaluate the decision alternatives.     

Do national levels of individualism and internal locus of control relate to well‐being: an ecological level international study

Data were collected from managers in 24 nations/territories on work locus of control (LOC), individualism–collectivism (I–C), and well‐being (job satisfaction, absence of psychological strain, and absence of physical strain). There were significant mean differences across samples on all five of these measures, and consistent with our hypothesis, at the ecological or sample mean level well‐being was associated with an internal locus of control. However, contrary to our hypothesis, well‐being was not associated with I–C, despite a strong correlation between I–C and LOC. Findings at the ecological level were consistent with the literature concerning the salutary effects of control on well‐being. Copyright © 2001 John Wiley & Sons, Ltd.     

A LONG‐TERM,WATERSHED‐SCALE,EVALUATION OF THE IMPACTS OF ANIMAL WASTE BMPs ON INDICATOR BACTERIA CONCENTRATIONS1

ABSTRACT: Driven by increasing concerns about bacterial pollution from agricultural sources, states such as Virginia have initiated cost sharing programs that encourage the use of animal waste best management practices (BMPs) to control this pollution. Although a few studies have shown that waste management BMPs are effective at the field scale, their effectiveness at the watershed scale and over the long term is unknown. The focus of this research was to evaluate the effectiveness of BMPs in reducing bacterial pollution at the watershed scale and over the long term. To accomplish this goal, a 1,163 ha watershed located in the Piedmont region of Virginia was monitored over a ten‐year period. Fecal coliforms (FC) and fecal streptococci (FS) were measured as indicators of bacterial pollution. A pre‐BMP versus post‐BMP design was adopted. Major BMPs implemented were manure storage facilities, stream fencing, water troughs, and nutrient management. Seasonal Kendall trend analysis revealed a significant decreasing trend during the post‐BMP period for FC concentrations at the watershed outlet, but not at the subwatershed level. Implementation of BMPs also resulted in a significant reduction in the geometric mean of FS concentrations. FC concentrations in streamflow at the watershed outlet exceeded the Virginia primary standard 86 and 74 percent of the time during pre‐BMP and post‐BMP periods, respectively. Corresponding exceedances for the secondary standard were 50 and 41 percent. Violations decreased only slightly during the post‐BMP period. The findings of this study suggest that although BMP implementation can be expected to accomplish some improvement in water quality, BMP implementation alone may not ensure compliance with current water quality standards.     

Life-cycle assessment of 11 kV electrical overhead lines and underground cables

The life-cycle impacts of five different 11 kV electrical power cables (three overhead lines and two underground cables) were analysed. These were compared by their embodied impacts in production and total lifetime operational impacts. The life-cycle results revealed there to be three key issues, the impacts of climate change, fossil fuel depletion, and particulate matter formation (PMF). The former two were of particular significance. The embodied impacts, which are those associated with the materials, were generally determined to be insignificant. The exception was for underground cables at low operating loads. Under these conditions PMF was more significant as a result of the high embodied impacts of the cables. Further analysis revealed that these impacts could be mitigated with an end of life material recovery program. At present the underground cables are not recovered, but if they were the recycling benefits would give rise to a notable improvement in PMF. For the other impact categories operational conductor losses were the dominant cause of impacts. In summary it was concluded that to minimise the life-cycle impacts of 11 kV cables the system with the lowest conductor resistance should be selected.