Jess W. Everett

Curbside recycling in the U.S.A. : convenience and mandatory participation

This research examines the relationship between the success of a residential curbside recycling program (RCRP), measured as material recovery rate (MRR), and two program factors: (1) whether or not participation is mandated; and (2) convenience, measured by container provision, collection frequency and collection day relative to municipal solid waste collection day. Residential curbside recycling programs, with correct strategies and program design, can be an important part of solid waste management plans world-wide. While residential curbside recycling programs are growing in popularity, many basic design questions lie unanswered and successful program strategies are not always obvious. Data from 357 residential curbside recycling programs in the United States are used to test the hypotheses. Mandatory participation residential curbside recycling programs are seen to collect more material than voluntary participation residential curbside recycling programs. Container provision appears effective for voluntary, but not mandatory, residential curbside recycling programs. Increasing collection frequency appears to have a small positive effect on residential curbside recycling program success, while collection day has little effect on material recovery rate.

Iron and sulfur mineral analysis methods for natural attenuation assessments

Abstract Based on electron acceptor abundance, Fe3+ and SO2− 4 reduction by bacteria may play a dominant role in intrinsic bioremediation of some organic contaminants in the subsurface. Both Fe3+ and SO2− 4 reduction processes involve mineral phases and may not be properly understood by evaluating only groundwater concentrations. Fe and S mineral analyses should be incorporated in natural attenuation studies; however, inherent problems with sample collection and analysis have discouraged such efforts. Methods are presented here for (1) sediment collection and anoxic preservation, (2) evaluation of biologically available Fe3+ and biogenically produced Fe2+ minerals, and (3) a simplified extended mineral sulfide analysis for ‐FeS and S°+FeS2. These techniques are demonstrated to evaluate Fe3+ and SO2− 4 reduction at three sites where the soil or aquifer matrix had been contaminated with gasoline fuel, methane gas, or landfill leachate. It is expected that these techniques will permit Fe and S mineral analys...

Microbial degradation of simulated landfill leachate: solid iron/sulfur interactions

Abstract Microcosms were prepared to test if added mineral Fe3+ and SO42− could treat landfill leachate and to examine intrinsic microbial/mineral interactions related to natural attenuation. Two oxidized native sediments were used from central Oklahoma. Three types of anoxic microcosms were prepared which included the addition of: (1) mineral ferrihydrite (Fe(OH)3); (2) mineral gypsum (CaSO4•2H2O); and (3) no mineral amendments. Each received a synthetic leachate consisting of 2000 mg/l non-purgable organic carbon (NPOC). Measurements of substrate consumption, dissolved ions, mineral utilization/precipitation, and biological gases were made over 12 weeks. The added CaSO42− and Fe(OH)3 were used as electron acceptors: CaSO42− by first order kinetics (k≅0.12 week−1) and Fe3+ by zero order kinetics (k≅0.16 mM week−1). The addition of either CaSO42− or Fe(OH)3 did not increase organic carbon degradation rates over methanogenesis, which was predominate in the non-amended microcosm set. Adding solid electron acceptors promoted carbonate and sulfide mineral formation and controlled greenhouse gases including CH4 and CO2. It is suggested that reduced Fe and S minerals could be used to assess organic contaminant degradation occurring due to Fe3+ and SO42− microbial reduction processes for natural attenuation studies.

Curbside collection of recyclables. I : Route time estimation model

Curbside collection of recyclable material can be expensive because the inherent costs of curbside collection are high, but also because amounts collected per residence are small compared to the total waste stream, and extra activity may be required, such as sorting. In this paper, a model is presented capable of estimating route time based on route and collection method characteristics. The time spent traveling over the route, between stops is estimated using the distance between stops. The time spent collecting materials is estimated using the distance walked by the collector(s) and the mass of material collected at each set-out. Time at stop signs and traffic lights is estimated using the average observed stop time. The model is tested for one and two-person collection methods used in the City of the Village, OK. It is capable of estimating route time within 10%, on average.

Curbside collection of recyclables. II. Simulation and economic analysis

Curbside collection of recyclable material can be expensive because the inherent costs of curbside collection are high, but also because amounts collected per residence are small compared to the total waste stream, and extra activity may be required, such as sorting. In this paper a simulation model is used to investigate the effect of collection method and route characteristics on route time. The simulation models presented calculate set-out amount based on route characteristics, set-out rate (SOR), and participation rate (PR). Route times are estimated for various conditions: constant SOR, constant PR, and constant set-out amount. Furthermore, a method for using route time to estimate vehicle and labor needs is presented, and used to estimate economic costs for one and two-person crew collection methods for the three simulation conditions mentioned above. The two-person crew is found to cost less than the one-person crew, for most simulated conditions.

Curbside Collection of Recyclable Material: Simulation of Collection Activities and Estimation of Vehicle and Labor Needs

This paper presents a mathematical model that can be used to estimate the time required to collect recyclable material (route time) by simulating the activities of a collection vehicle driving over its route. Data obtained by observing the collection of recyclable material in The Village, OK, were used to determine parameters for the model. The validity and robustness of the model were tested by comparing model-predicted route time to observed route time. The model was able to predict route time within 8%. Simulation procedures are presented that can be used to estimate route time under conditions not actually ob-served-for instance, very low or high rates of material being set out for collection. The simulation procedures, incorporating randomly assigned set-out distributions, indicate that set-out distribution (proximity of houses setting out materials) has little effect on route time. Vehicle and labor needs for the curbside collection of recyclable material in a hypothetical town are estimated to demonstrate a practical application of the simulation procedure. The results indicate that if set-out rate were to increase from 20% to 30%, labor needs would increase by 34% and an additional vehicle would be needed to serve the same number of households. Increasing set-out rate from 20% to 40% would result in a labor requirement increase of 68%. Calculations such as these are particularly significant if a program to increase participation is being considered.

Measuring the success of recycling programs

Abstract Drawing from resource recovery unit operations research, a single-value-parameter reflecting both material recovery and purity considerations is suggested for calculating recycling program efficiency. Other measures of success are presented and data from a 1989 survey of over 1200 residential curbside recycling programs are used to assess the degree to which these measures are used. The ability of block leaders to estimate block participation rates is also explored. Two important measures of recycling program success which do not take into account purity considerations are presented, annualized per capita material recovery rate (MRR), and annualized per capita recycler material recovery rate (RMRR) as is the participation rate (PR). It is suggested that, in conjunction with the annualized per capita material availability rate (MAR), knowledge of PR and RMRR can be used to determine program recruitment strategy. If PR is low, program recruitment strategy should target non-recyclers. If RMRR is low compared to MAR, strategies should encourage participants to recycle a greater percentage of the available recyclable material. Survey results indicate that success measures MRR and PR are under-utilized and unstandardized. Block leaders appear to be able to estimate general levels of block participation, but not specific participation rates.

The impact of a living learning community on first-year engineering students

The purpose of this study was to investigate the impact of an engineering living and learning community (ELC) on first-year engineering students. A control group of non-ELC students was used to compare the experiences of the ELC participants. Analysis of survey data showed that there was significant differences between the ELC students and the non-ELC students in how they responded to questions regarding social support, academic support, connectedness to campus, and satisfaction with the College of Engineering and the institution as a whole. Particularly, there were significant differences between ELC and non-ELC students for questions related to feeling like part of an engineering community, having strong relationships with peers, belonging to a supportive peer network, studying with engineering peers, and spending time with classmates outside of class.

EVALUATION OF CULVERT PIPE MADE FROM WASTE TRUCK TIRES

Waste truck tires pose special disposal problems. As an alternative to disposal, a private tire recycling company developed a pipe from the tire bead and sidewall. This tire pipe has seen limited use as a roadway drainage culvert. To encourage wider use of this product, an evaluation of its performance was performed. The evaluation consisted of (a) inspections of existing installations, (b) receiving comments from installers and owners, and (c) leakage tests. The field investigations revealed that most tire pipe installations were performing well. An individual tire pipe section was found to be watertight. However, when tested in the open air (not in the ground), the tire pipe joint was found to leak. Development of an improved end connection may improve the utility of the tire pipe.

Field application of biogeochemical reductive dechlorination by permeable reactive barrier

Biogeochemical reductive dechlorination (BiRD) uses biotically generated iron sulphide minerals to abiotically reduce chlorinated aliphatic hydrocarbons (CAH). BiRD was applied by permeable reactive barrier (PRB) at Dover Air Force Base, the first time this approach was tested in the field. Iron sulphide minerals were generated in trenches filled with iron rich sand (iron), mulch (organic), mineral gypsum (sulphate), and limestone (pH control). For comparison purposes, trenches were also filled with sand, mulch, and limestone to create conditions favourable to biostimulation. Compared to biostimulation, BiRD showed little evidence of methanogenesis, indicating that the reductive capacity of the applied organic was converted to mineral iron sulphide rather than methane. CAH treatment in the biostimulation PRB appeared to be incomplete after 150 days, apparently stalling at DCE. In comparison, for the BiRD treatment area, CAH treatment appeared to be rapid and reduced PCE, TCE and DCE levels within the 150 day time period.