A. Scott Weber

USE OF METAL ADSORBING COMPOUNDS (MAC) TO MITIGATE ADVERSE EFFECTS OF HEAVY METALS IN BIOLOGICAL UNIT PROCESSES

Abstract The presence of heavy metals on an intermittent basis in the influent of biological unit processes can lead to process upset and poor removal of organics. Heavy metal breakthrough from a pretreatment process may be caused by a number of reasons. In this study, the feasibility of adding metal adsorbing compounds (MACs) into a sequencing batch reactor (SBR) to mitigate the adverse effects of heavy metals breakthrough was investigated. A powdered activated carbon was found to be an effective MAC for heavy metals concentrations varying from 2 to 20mg/L. Organic removal efficiencies in a SBR using MACs were similar to those of a control SBR with no metals in the influent.

Congener Level PCB Desorption Kinetics of Field-Contaminated Sediments

The purpose of this research was to study congener level PCB desorption kinetics of field-contaminated sediments and develop a simple methodology to analyze the desorption behavior. Batch desorption kinetic studies were conducted using XAD-4 resin. Two-phase desorption kinetics were observed for most PCB congeners, consisting of an initial fast rate followed by an extended period of slow rate. A dual first-order rate model was fitted to the PCB desorption data to estimate PCB concentrations in the fast and slow desorbing pools. The fast and slow desorption rates were found to decrease with increasing chlorina-tion of PCB congeners, decreasing ortho chlorination, and decreasing temperature. Estimated first-order desorption rate constants for the fast pools were found to be two orders of magnitude higher than those for the corresponding slow pools. The log of first-order rate constants for the different PCB congeners were found to be linearly related to the log of octanol-water partition coefficients. There...

Continuous culture biodegradation of simazine's chemical oxidation products

Abstract Experimental studies were conducted to assess the continuous culture biodegradation of s -triazines which originate from the chemical oxidation of simazine. Simazine is a herbicide found widely in surface and groundwaters. The four s -triazines selected for study, didealkyl atrazine (CAAT), ammeline (OAAT), ammelide (OOAT), and cyanuric acid (OOOT), originate from the ozone/UV oxidation of simazine. Decreases in continuous culture net growth rate, decreases in C: s -triazine-N feed ratio, and increases in inorganic nitrogen either through addition to the feed or by nitrogen fixation resulted in poorer s -triazine removal. For each process variable studied, the reduction in removal efficiency was s -triazine specific. In general, the greatest reductions in removal efficiency was observed for CAAT followed by OAAT, OOAT, and OOOT indicating that the s -triazine ring substituent group is an important factor in determining its effectiveness as a nitrogen source for microbial metabolism. The relationship between ring substituent and s -triazine metabolism demonstrates the beneficial role that chemical oxidation can play in subsequent s -triazine biodegradation. The application of chemical oxidation may enable the use of existing biological process infrastructure, primarily municipal POTWs where nitrogen limitations do not typically exist, for the treatment of s -triazines.

Dissolved PCB congener distribution in generator column solutions

Abstract A generator column technique previously used to study the solubility of sparingly soluble compounds, has been employed in this study to prepare high throughput aqueous PCB solutions for use in treatability studies. In the present study, Aroclor 1242 mixture was used to load the generator column. The total PCB concentration and the PCB congener distribution pattern in the effluent changed with time, with lower chlorinated congeners eluting faster than the higher chlorinated ones. Collection of over 300 bed volumes of effluent from two such generator columns provided PCB solutions which showed 75–90% similarity to the original Aroclor 1242 congener distribution. In this paper, the observed distribution of PCB congeners in the generator column effluent with time is presented and discussed. A reasonable prediction of effluent PCB concentration from the generator column was possible using Raoults Law for ideal solutions.

Background Concentrations of Polycyclic Aromatic Hydrocarbon (PAH) Compounds in New York State Soils

Using information from a variety of published studies, a data set was assembled with approximately 200 surface soil samples collected from urban locations across New York State (NYS) not directly influenced by known sources of contamination. Statistical characteristics for 17 polycyclic aromatic hydrocarbon (PAH) compounds were examined and compared with draft NYS soil cleanup objectives that had been developed using risk-based and rural background considerations. For the carcinogenic PAH compounds, approximately 12–40% of samples exceeded cleanup objectives proposed for residential land use, but few samples exceeded the less stringent standards proposed for commercial and industrial properties. Qualitative comparisons with a recent study of NYS rural soils indicated substantial differences in background PAH levels between urban and rural locations. These findings motivate further research into the best manner for incorporating background information into soil cleanup objectives for urban areas.

Use of continuous-flow UV-induced mutation technique to enhance chlorinated organic biodegradation

SummaryIn this study, a continuous-flow UV-induced mutation (CUM) device and the CUM device coupled to a selector (CUMS) reactor were fabricated and tested for their ability to enhance the probability of obtaining populations capable of chlorinated organic biodegradation. A mixed culture of bacteria were used as the starting strain for both the CUM and CUMS processes. Populations were obtained from the CUM and CUMS systems capable of 4-chlorobenzoic acid, 2,4-dichlorobenzoic acid and chlorendic acid biodegradation. Non-UV irradiated population served as controls for the experiments and did not demonstrate chlorinated organic biodegradation over the test duration.

A Numerical Investigation of Impact of Architectural and Climatic Parameters of Windcatcher Systems on Induced Ventilation

The large energy demand from the HVAC industry for residential buildings, along with the ever growing need for the utilization of renewable sources of energy, has brought considerable attention to the area of induced ventilation. Windcatchers are green architectural structures historically used for the passive ventilation of the indoor spaces with the minimal non-renewable energy consumption. In this paper, a computational fluid dynamics (CFD) model is used to assess a windcatcher’s performance with different characteristics of the windcatcher design. For a single room with heat emitting objects, the effects of the windcatcher louver design and height were thoroughly evaluated in conjunction with a variety of dominant wind velocity and incident angles. A comparison was drawn between the ventilation efficiency for the cases of circular and rectangular windcatcher designs. Thermal discomfort (PD) values due to draft were calculated for different temperature and wind velocities. The developed model was employed to obtain the optimized configuration for the windcatcher-room system. The effect of ambient weather conditions on the results was investigated by performing the simulations for a range of air temperature and velocities. Results obtained in this paper provide windcatcher designers with valuable insights on the important design parameters such as windcatcher height, louver design and impact of ambient conditions.Copyright

Sequential chemical/biological oxidation of chlorendic acid

Chlorendic acid, a fire retardant, was subjected to sequential chemical/biological oxidation. Degradation of chlorendic acid was achieved by ozonation with chlorinated and non-chlorinated by-product production. The destruction of chlorendic acid and by-product distribution was a function of ozone contact time. After 450 min of ozonation, chlorendic acid and TOC removal percentages equaled 98% and 62.5%, respectively. When subject to 210 min of UV oxidation, chlorendic acid and TOC removal equaled 70 and 31%, respectively. With combined ozone/UV, near complete removal of chlorendic acid and TOC was achieved in 90 and 120 min, respectively. In biodegradation testing, chlorendic acid was not degradable. Biodegradation efficiency (DOC removal) of chlorendic acid ozonation by-products was a function of ozone contact time and approached 80%. Chlorendic acid UV oxidation products (210 min contact time) were poorly biodegraded. Ozone/UV oxidation products (40 min contact time) from chlorendic acid achieved 89% biodegradation. Biodegradation rates of chlorendic acid chemical oxidation by-products also were assessed. Based on the computed biokinetic values of biodegradation rates for the chemical oxidation products of chlorendic acid are sufficiently high to enable use of existing biological process infrastructure for treatment of chemical oxidation products.

Streptomycin-resistant mutant production in a continuous-flow UV mutation device

SummaryA continuous-flow UV-induced mutation device which incorporates starting strain cultivation, UV irradiation and mutant reproduction was conceptualized and tested in this study using streptomycin resistance as an indicator of mutant production. For the experimental conditions employed and populations used, the mutation frequency for streptomycin resistance ranged from 10−4 to 10−5 cfu/ml. These mutation frequencies are comparable with conventional batch UV mutation methods and represent a gain of 3 orders of magnitude over the spontaneous mutation frequency.

A New Control Strategy to Improve the Ground Source Heat Pump’s Efficiency With a Recycled Product

Despite numerous efforts to impose control measures on the heat pump side of Ground Source Heat Pump (GSHP) systems, there has been little thought into the potential of control on the ground characteristics. This is perhaps because of a predisposition to believe that ground related works usually are associated with extra capital investment that makes any modification less favorable than making changes to the heat pump unit. An effective control strategy with a non-homogeneous soil profile for the ground side of horizontal GSHPs was investigated in this research. The model incorporates the effects of a variety of surface energy fluxes to provide an accurate estimate of the ground thermal regime. The developed model was utilized successfully in conjunction with the MATLAB Genetic Algorithm (GA) toolbox to obtain the optimized operational parameters for a GSHP in a cold climate condition (Buffalo, NY). A properly sized and engineered non-homogeneous soil profile demonstrated the potential to boost the capacity of GSHP systems to a significant level. The potential benefits of a recycled product of tire industry, Tire Derived Aggregate (TDA), as an insulation blanket was assessed via the optimization algorithm. TDA was demonstrated to be effective in heating mode in a cold climate environment by increasing the energy extraction rates from the ground by about 15% annual. The annual percentage increase in energy dissipation rate to the ground, in cooling season, with TDA blanket was 7.6%. The results are suggestive of the beneficial application of a layered system to increase the performance of GSHPs. A shift in design perspective toward consideration of more control strategies for the ground pipe side of GSHPs is suggested based on the model results.Copyright