Source Reductions Research Articles

Bioconversion of toluene to p-hydroxybenzoate

Biocatalytic production of p-hydroxybenzoate (HBA) provides improved regiospecificity over Kolbe–Schmitt carboxylation of phenol while achieving significant source reductions in the generation of waste and byproducts. Construction of the organism for HBA production was accomplished through two classical approaches for the engineering of organisms in the production of specialty chemicals: (1) strain enhancement through chemical mutagenesis to create a mutant Pseudomonas putida, EM2839, deficient in HBA degradation, and (2) hybrid pathway construction through the recruitment of genes encoding the toluene-4-monooxygenase (T4MO) (tmoABCDE), p-cresol methylhyroxylase (pchCF), and p-hydroxybenzaldehyde dehydrogenase (phbz) genes from existing pathways and stably incorporating them into the organism through the use of mini-Tn5 transposon systems.Time course measurements of HBA production by resting cells of P. putida EM2878 in batch cultures revealed that T4MO conversion of toluene to p-creseol, the first step in the pathway, significantly constrained the carbon flux in the pathway, yielding a maximum rate of HBA production of 1.61 ± 0.15 nmol min–1 mg protein–1. In fed-batch culture, toluene conversion to HBA by P. putida EM2878 showed absolute selectivity for para-hydroxybenzoate production. Maximum HBA concentrations of 35 mg l–1 were achieved in about 28 hours of operation. However, the rate of HBA production was significantly less than that observed during batch studies. The slower rate of HBA production observed in the fed-batch culture was correlated with the degradation of specific T4MO polypeptides.

Chemical/petrochemical wastewater management—past, present and future

This paper summarizes and evaluates past, current and expected actions concerning waste management in the chemical and petrochemical industries. Industrial waste management has evolved from an “end of pipe” treatment mentality to holistic environmental waste management with source reductions as the preferred option. In most cases significant costs savings have resulted and environmental and public health impacts minimized. This current thrust has resulted from recent regulatory actions. Future trends will require management changes. To be effective, the management approach selected must address the following issues: regulatory/legal considerations and trends; environmental management systems; toxicity measurement characterizations; ecotoxicity assessment evaluations; source reduction and waste minimization; treatment trends and innovative treatment techniques; residual management.

Reproductive growth of maize, sunflower and soybean at different source levels during grain filling

Maize ( Zea mays L.), sunflower ( Helianthus annus L.) and soybean ( Glycine max (L.) Merr.) are sometimes subjected to stress that affects source capacity during the grain filling period. Effects of variations in source capacity during grain filling on yield and its components in these crops were examined with shading and thinning treatments. Shading reduced grain yield in the three crops. Average percent reductions were greatest for sunflower and least for maize. In soybean and sunflower, the number of grains was more affected than weight per grain, whereas the opposite was true in maize. Average grain yield per plant was greatly increased in soybean and sunflower and slightly affected in maize when source per plant was increased by thinning. Grain number was the yield component most affected in soybean and weight per grain in sunflower. Neither treatment affected grain filling rate of maize, whereas shading reduced effective grain filling duration. Contrarily, the source treatments affected the rate of grain filling in sunflower and in soybean. Variations in source capacity during grain filling affected grain quality much more in sunflower and maize than in soybean. In general, thinning treatments resulted in the highest levels of sugars in stems and shading treatments the lowest. Maize would be the crop with the largest capacity to buffer source reductions during grain filling. In conclusion, modification of source capacity during grain filling had more impact on plant yield in sunflower and soybean than in maize and affected grain quality mainly in maize and sunflower.

Chemical/petrochemical wastewater management--past, present and future

This paper summarizes and evaluates past, current and expected actions concerning waste management in the chemical and petrochemical industries. Industrial waste management has evolved from an “end of pipe” treatment mentality to holistic environmental waste management with source reductions as the preferred option. In most cases significant costs savings have resulted and environmental and public health impacts minimized. This current thrust has resulted from recent regulatory actions. Future trends will require management changes. To be effective, the management approach selected must address the following issues: regulatory/legal considerations and trends; environmental management systems; toxicity measurement characterizations; ecotoxicity assessment evaluations; source reduction and waste minimization; treatment trends and innovative treatment techniques; residual management.

Upward trend in soluble phosphorus loadings to Lough Neagh despite phosphorus reduction at sewage treatment works

After allowing for changes in point source phosphorus (P) loadings from sewage treatment works (STWs) and creameries, an upward trend in the soluble reactive phosphorus (SRP) loadings in the six major rivers draining into Lough Neagh was established over the period 1974–1991. Urban SRP loadings were reduced by a P reduction programme at nine major STWs, which commenced in 1981, while the loading from other STWs was considered to have been stable as population growth was balanced by reduced P per capita loadings reflecting reductions in the P content of domestic detergents. Post 1987, creamery loadings were reduced following closures and a switch away from phosphoric acid as a cleaning agent. STWs were subjected to P reduction in four river catchments but reductions in SRP loads of these rivers were only comparable to the reduction in STWs loadings of SRP for a period of up to four years. Of the two remaining rivers, one experienced no major change in point source P loadings from 1974 to 1991, over which time a steady increase in SRP loadings occurred, while a similar SRP loading increase was also detected in the remaining river over a 12 year period when point sources were quite constant. In all river catchments, long-term changes in loadings or the short-term response to point source reductions could only be made after taking into account the variation in river SRP loads due to annual flow variations. The rates at which SRP loadings were increasing was in the range 1.30 to 1.45 kg P km −2 yr −1.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 12. Effects on Man, Animals, and Plants as a Function of Air Pollutant Impact

The impact-effect mathematical model, developed in 1991, improves on a previous mathematical model, and was developed to predict biological response as a function of air pollutant impact. Impact is defined here as exposure duration multiplied by air pollutant concentration raised to an exponent (t.cd). This paper's purpose is to plot and regress example biological effects as a function of air pollutant impact to determine how well the plotted data fit the impact-effect model for three target populations: man, animals, and plants (a wide range of life forms). The three biological effects are: for man, lung function decrease after exposure to ozone (O3); for animals, mouse mortality after exposure to nitrogen dioxide (NO2); and for plants, leaf injury after exposure to O3. The three resultant regression equations account for a substantial amount of the data variance: 95 percent for lung function, 92 percent for leaf injury, and 73 percent for mouse mortality. The model fits the animal and plant data that cover both acute and chronic exposures. The animal exposures ranged from 6 min to 1 yr. The plant exposures ranged from 0.75 to 552 h.

Point Source Loadings of Phosphorus to Lake Erie: 1986–1990

Point source phosphorus control became a priority with all of the jurisdictions around Lake Erie since the signing of the Great Lakes Water Quality Agreement in 1972. Major municipal sewage treatment plants were limited to 1 mg/L total phosphorus and phosphorus loadings to Lake Erie have decreased significantly. Recent estimates of point source loadings from municipal and industrial sites in the Lake Erie basin show that these improvements have continued as smaller sources are providing treatment and larger sources are achieving better control. For larger plants, compliance on a monthly basis is approaching 100%. Because of this, further point source reductions cannot exceed about 50 tonnes per year unless a lower phosphorus limit is established.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 11. A Lognormal Model Relating Human Lung Function Decrease to O3 Exposure

Forced expiratory volume in 1 second (FEV1) was measured in 21 men exercising while exposed to four O3 concentrations (0.0, 0.08, 0.10, and 0.12 ppm). A lognormal multiple linear regression model was fitted to their mean FEV1 measurements to predict FEV1 percent decrease as a function of O3 concentration and exposure duration. The exercise level used was probably comparable to heavy manual labor. The longest O3 exposure studied was 6 h. Extrapolating cautiously to an 8-h workday of heavy manual labor, the model predicts that O3 concentrations of 0.08, 0.10, and 0.12 ppm would decrease FEV1 by 9, 15, and 20 percent, respectively.

Hazardous-Waste Minimization in the Naval Shipyards

Regulations and other costly constraints affecting the handling and disposal of hazardous waste materials are becoming increasingly restrictive and costly. Hazardous waste has become one of the most critical problems facing our nation today. Fines and criminal charges against companies and individuals for noncompliance are increasing. Disposal sites are decreasing. Real costs can amount to 10 to 15 times the original purchase price for hazardous materials. Future prospects are that the problem will certainly grow worse. The naval shipyards have taken an aggressive approach to waste minimization. Using industrial-engineering techniques, the shipyards are implementing source reductions to reduce the quantities of hazardous generation as a by-product of their industrial processes. This paper discusses the problems associated with hazardous waste and describes a program to minimize the generation of this waste.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 10. Potential Ambient O3Standards to Limit Soybean Crop Reduction

Soybean percent crop reduction was estimated as a function of ambient O3 concentrations for each of 80 agricultural sites in the National Aerometric Data Bank (NADB) for each available year of data for years 1981-1985. Fourteen O3 concentration statistics were calculated for each of the resulting 320 site-years of data. The two statistics that correlated best with estimated crop reduction were an effective mean O3 concentration (1 percent of variance unexplained) and an arithmetic mean O3 concentration (4 percent unexplained). The worst correlation of the 14 was for the statistic used in the present O3 National Ambient Air Quality Standard (NAAQS), the second highest daily maximum 1-h O3 concentration (42 percent unexplained). The number of site-years for estimated percent soybean yield reductions was plotted versus increasing O3 concentrations for each of the 14 O3 statistics. A maximum crop reduction line was drawn on each plot. These lines were used to estimate (and list) potential ambient O3 standards for each of the 14 statistics that would limit soybean crop reduction at agricultural. NADB sites to 5, 10, 15, or 20 percent.

Diffuse (Non-Point) Source Loading of Chemicals to Lake Erie

Studies of chemical loadings to Lake Erie over the last two decades show that the lake, because of its small volume to drainage area ratio, and the intensive agricultural, industrial, and urban land uses of its watersheds, has been a receptor of a myriad of natural and anthropogenic chemicals. Of these, phosphorus, trace metals, PCBs and other organics and pesticides have received the most attention. Phosphorus reduction plans already in place have produced dramatic decreases in point-source P loadings and observable improvements in lake water quality. Target P loads for complete lake restoration will not be met, however, until substantial reductions of agricultural non-point sources are obtained, and gains in this area are likely to be much slower and more difficult to attain. Source reductions of trace metals and the older chlorinated insecticides have produced some decreases in diffuse loadings of these chemicals although their biomagnification in lake biota means that their impact on the lake will continue for many years. Today, the emphasis has shifted to a broader range of anthropogenic organic chemicals including highly mobile herbicides which have been shown to contaminate Lake Erie basin drinking water supplies, and to easily biomagnified toxics which, with relatively small loadings, can have a major impact on higher species.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 9. Calculating Effective Ambient Air Quality Parameters

The overall purpose of air pollution control is to reduce or eliminate adverse effects, such as plant injury or crop reduction. In order to study and to control such adverse effects efficiently, air quality parameters are needed that correlate closely with the effects, as does the effective mean concentration: wherec h, is the 1-h average ambient air pollutant concentration measured at a site for each daytime hour (defined here as 9:00 A.M.-4:00 P.M., always standard time) in a plant’s growing season, n is the number of hours of such available data, and vis a concentration-time parameter (−0.376 is always used here, based on previous studies). Ambient air quality data can often be characterized by the two characteristic parameters of the lognormal distribution, the geometric mean and the standard geometric deviation, but some ambient data are far from lognormal. This paper suggests that even though an air quality data set is not lognormal, the effects of the concentrations can be characterized with an eff...

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 8. An Effective Mean O3Crop Reduction Mathematical Model

A plant injury mathematical model, applied previously to acute and chronic leaf injury data, is used here to model National Crop Loss Assessment Network (NCLAN) data for 15 cultivars and to calculate species parameters from the cultivar analyses. Percent crop yield reduction is estimated as a function of a new parameter, the effective mean O3 concentration: me = [(Σ ch −1/v)/n]−v, where ch is the hourly average ambient O3 concentration for each daytime hour (defined here as 9:00 A.M.–4:00 P.M., always standard time) of data available at an air sampling site for summer (defined here as June 1–August 31), n is the total number of such available hours, and v is an exposure time-concentration parameter, calculated here to be approximately –0.376. Crop yield reduction for soybean is calculated here as z = 0.478 In (tme 2-66) – 0.42, where z is the Gaussian transform of percent crop reduction, t is the hours of exposure (525 h is used here; 7 h/day for 75 days), and In indicates that the natural logarithm is ta...

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 7. An O3-SO2Leaf Injury Mathematical Model

Leaf injury data from acute and chronic exposure studies of Dare soybean were regressed against the logarithms of exposure time and O3 and SO2 concentrations to develop a new two-pollutant leaf injury model (which explains 88% of the variance) and to calculate the parameters of best fit for this new model and a previously developed one-pollutant model. Using the calculated parameters, the percentage of leaf surface Injured over a growing season by O3, SO2, or both simultaneously was estimated for an ambient air sampling site located 2 miles from a coal burning power plant. For this site, the one- and two-pollutant models predicted that SO2 effects would be negligible If SO2 concentrations never exceeded the National Ambient Air Quality Standard (NAAQS) of 0.50 ppm, averaged over 3 h. However, calculations suggest that O3 may injure up to 24% of Dare soybean leaf surface over a growing season even though the O3 NAAQS of 0.12 ppm, averaged over 1 h, is never exceeded. Because the 3 h SO2 standard is exceeded at very few places, the O3 model is usually sufficient to estimate Dare soybean leaf Injury. Leaf injury is estimated by taking the logarithm of the summation of each daytime hour’s exponentiated O3 concentration (c) measured at an ambient air sampling site over a growing season. This is expressed as: z = -0.0828 + 0.4876 in (Σco3 2.618), where z is the Gaussian transform of percent leaf injury. The methods developed in this paper, using Dare soybean data as an example, may apply to other plants.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 6. Calculating Concentration Reductions Needed to Achieve the New National Ozone Standard

The new ozone National Ambient Air Quality Standard specifies that the expected number of days per calendar year that the 1 hour average ozone concentration can exceed 0.12 ppm must be equal to or less than 1. This paper describes a method to calculate design frequency, design concentration, and the percentage concentration reduction necessary to achieve this standard. The design frequency is once per year (1/365) if daily maximum hour ozone concentrations are available at a particular site for an equal number of days in summer (April through September) and winter (October through March). An equation is used to adjust design frequency as a function of the number of summer and winter samples available. The design concentration (the ambient concentration measured at the design frequency) needs to be reduced to 0.12 ppm. Graphical and digital methods for determining the design concentration are presented. Percentage concentration reductions needed to achieve the standard are calculated for each site which has ozone concentration data available in the National Aerometric Data Bank for at least half of the days in one summer of years 1975 through 1977. The degree of reduction calculated for the site with the highest concentrations in each county is indicated by shading on a map of the United States.

Simulation of Recent and Projected Total Phosphorus Trends in Lake Ontario

Recent trends (1965 through 1978) of total phosphorus were analyzed with a time-variable, nutrient budget model of Lake Ontario. Future conditions were also simulated to estimate the effect of anticipated control measures on the lake's water quality. The analysis suggests that recent improvements in Lake Ontario's total phosphorus concentration are attributable to point source reductions due to detergent limitations and waste treatment by the Province of Ontario and the State of New York. Projections show that present point source controls will maintain the lake at the upper level of mesotrophy (15-20 μgP/L) to the year 2000, whereas the absence of controls would result in eutrophy (∼30 μgP/L). Further indications are that some diffuse source reduction may be required if oligotrophy (<10 μgP/L) is the ultimate goal and that Lake Ontario's fate is closely related to that of Lake Erie. An attempt is made to assess the effect of model uncertainty and phosphorus availability on the projections. In general, the inclusion of uncertainty indicates that more stringent load reductions will be needed to meet water quality objectives with greater than 50% certainty. Inclusion of availability tends to improve prospects for lake restoration and to enhance point as opposed to diffuse source controls.

An air quality data analysis system for interrelating effects, standards, and needed source reductions: part 5. NO2 mortality in mice.

Mice have been exposed for durations of 6 min to 1 yr to N02 concentrations of 0.5 to 28 ppm. Exposed mice and control mice have then inhaled an aerosol containing a lung pathogen and the excess mortality of exposed mice (compared with control mice) has been determined. A mathematical model (similar to a previously-developed model for vegetation injury) has been developed from an analysis of the resulting data to calculate expected excess mortality as a function of N02 concentration and exposure duration. Excess mortality was found to be proportional to N02 concentration multiplied by exposure duration raised to the 0.33 power. The concentration (c) expected to cause a certain mortality level (z), as a function of the hours of exposure (t), can be expressed as c = 9.55(2.42) zt0-33 The model has been used to calculate expected excess mortality (1.1 %) if mice had inhaled the ambient N02 concentrations measured in downtown Chicago for each hour of 1974 (1 yr arithmetic mean of 0.05 ppm, the same as the pre...

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 4. A Three-Parameter Averaging-Time Model

Urban air pollutant concentration data often tend to fit a two-parameter averaging-time model having three characteristics: (1) pollutant concentrations are (two-parameter) lognormally distributed ...

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 3. Vegetation Injury

Acute leaf injury data are analyzed for 19 plant species exposed to ozone or sulfur dioxide. The data can be depicted by a new leaf injury mathematical model with two characteristics: (1) a constant percentage of leaf surface is injured by an air pollutant concentration that is inversely proportional to exposure duration raised to an exponent; (2) for a given exposure duration, the percent leaf injury as a function of pollutant concentration tends to fit a lognormal frequency distribution. Leaf injury as a function of laboratory exposure duration is modeled and compared with ambient air pollutant concentration measurements for various averaging times to determine which exposure durations are probably most important for setting ambient air quality standards to prevent or reduce visible leaf injury. The 8 hour average appears to be most important for most of the plants investigated for most sites, 1 hr concentrations are important for most plants at a few sites, and 3 hr S02 concentrations are important for...

An Air Quality Data Analysis System For Interrelating Effects, Standards, And Needed Source Reductions—Part 2

The United States national ambient air quality standards specify, for averaging times of 24 hours or less, that the standard concentration is not to be exceeded more than once a year. If the expected annual maximum concentration (expected to occur an average of once a year) is used as the design value in determining source reductions, then these standards will probably be violated (exceeded more than once a year) in about 1 year out of 8. Similarly, annual standards will probably be violated in about 1 year out of 8 if the expected 5 year maximum concentration is selected as the design value in determining source reductions needed to achieve these annual standards. Use of such design values is recommended. The averaging-time mathematical model has generally been used with a 1 year base. From now on, it is recommended that it be used with a 5 year base. The tables needed for a 5 year base are given, and their use for calculating design values is shown.