Qizhong Guo

Heavy metal outputs from a cement kiln co-fired with hazardous waste fuels

Measured data from a kiln equilibration test are analyzed for heavy metal outputs from a cement kiln co-fired with hazardous waste fuels. Metal outputs from stack emissions, cement kiln dust and cement clinker are considered. Equations are derived for predicting all three metal outputs at any hazardous waste feed rate under steady state conditions. Through analysis of two steady state conditions, at the beginning and end of the equilibration test, essentially the same ratios of metal feed rates are found to be distributed to the kiln dust at either high or low metal feed rates. Applying the same distribution ratios in the derived equations, metal concentrations of wasted kiln dust are predicted when the kiln is not using hazardous waste fuels. Measured concentrations of arsenic, beryllium, cadmium, chromium, and lead in wasted kiln dust, at the highest intended hazardous waste feed rates to the kiln, are 68, 10, 72, 18, and 68 times those predicted for feed rates with no hazardous waste. In addition, the intermediate, non-steady state segment of the equilibration test is analyzed. If metals are assumed not to accumulate in the kiln, the intermediate metal concentrations in cement clinker are predicted to be substantially higher than those at the final steady state.

Increases of lead and chromium in drinking water from using cement-mortar-lined pipes: initial modeling and assessment

Abstract A mathematical leaching model was developed for assessing potential increases of lead and chromium in drinking water from using cement—mortar-lined pipes. The initial wetting process, dissolution, diffusion, and advection of metals in the lining, accumulation of metals in the static pipe water, and dilution of metals by the flowing water were considered. Values for physical and chemical parameters in the model were obtained from literature or were estimated. Based on the modeled results, the drinking water standards are likely to be exceeded by using cement with lead solubility larger than 70 ppb or chromium solubility larger than 540 ppb. For one cement kiln studied, it is recommended that cement kiln dust not be fully recirculated when hazardous waste fuel (HWF) has the maximum allowable amount of lead. It is also recommended that the maximum allowable amount of chromium in HWF be lowered.

Dynamic risk assessment model for flood disaster on a projection pursuit cluster and its application

Aiming at reducing the losses from flood disaster, a dynamic risk assessment model for flood disaster is studied in this article. This model is built upon the projection pursuit cluster principle and risk indexes in the system, proceeding from the whole structure to its component parts. In this study, a fuzzy analytic hierarchy approach is employed to screen out the index system and determine the index weight, while the future value of each index is simulated by an improved back-propagation neural network algorithm. The proposed model adopts a dynamic evaluation method to analyze temporal data and assesses risk development by comprehensive analysis. The projection pursuit theory is used for clustering spatial data. The optimal projection vector is applied to calculate the risk cluster type. Therefore, the flood disaster risk level is confirmed and then the local conditions for presenting the control strategy. This study takes the Tunxi area, Huangshan city, as an example. After dynamic risk assessment model establishment, verification and application for flood disasters between the actual and simulated data from 2001 to 2013, the comprehensive risk assessment results show that the development trend for flood disaster risk is still in a decline on the whole, despite the rise in a few years. This is in accordance with the actual conditions. The proposed model is shown to be feasible for theory and application, providing a new way to assess flood disaster risk.

Sediment Monitoring Bias by Automatic Sampler in Comparison with Large Volume Sampling for Parking Lot Runoff

A field study was conducted to assess biases of suspended sediment concentration (SSC) analyses (ASTM Standard D3977-97) performed on discrete samples obtained by automatic sampler in comparison with actual sediment concentrations from large volume sam- pling. Research results indicate that the biases attributed to the monitoring of sediment event mean concentration (EMC) and median particle size in parking lot runoff by automated samplers (nonisokinetic) were minimal. Large volume samples (∼15;000 L) of the first-flush event runoff were taken from a storm-water sewer system for eighteen storm events over two years. The intent was to obtain a complete portion of a storm to accurately determine EMCs and particle size distributions (PSDs). Concurrently, flow-weighted discrete samples were obtained by automatic samplers for the same portion of the events. Thus, characteristics of sediments from a whole-storm sample were compared with those of subsamples obtained by an automatic sampler using nonisokinetic sampling. SSCs and PSDs were compared for the two respective field sampling methods. The two methods showed a strong correlation for median sediment EMCs (R 2 ¼ 0:98, n ¼ 18). Biases to particle size distributions were found to be both for the large particles (> 75-150 μm) and smaller fines (< 25 μm). Specific sediment size fractions captured by the large volume sampling and automatic sampler were not significantly different (α ¼ 0:05) for D50, which = 58 and 46 μm, respectively. DOI: 10.1061/(ASCE)IR.1943-4774.0000168.

Hydraulic and Water Quality Performance of Urban Storm Water Detention Basin Before and After Outlet Modification

Many existing storm water dry detention basins designed solely for storm water runoff peak discharge magnitude abatement as well as detention basins designed both for water quality and quantity control fail to achieve necessary levels of non-point source pollutant loading reduction. This correctable situation has necessitated the demonstration of various retrofitting techniques on existing systems. An easy and relatively inexpensive retrofitting technique is modification of the basin outlet. The area chosen for such a project was a single-family home development community located in Morris Township, New Jersey. The first modification to the existing dry detention basin consisted of the reduction of the pipe outlet diameter, by placing an outlet box in front of the existing outlet pipe. The second modification was attaching a floating riser, a buoyant outlet device, to the outlet box. The floating riser removes only the surface layer of an impounded storm. Either basin modification resulted in a longer detention time than the original basin did for the same volume of runoff inflow. However, no conclusive correlation between the pollutant removal efficiency and the detention time was determined. Rather, it was found that the pollutant removal efficiency in the field was strongly dependent on the inflow concentration. Therefore, the pollutant removal efficiency must be evaluated in the context of variable inflow concentration. The outflow concentration may be a more reliable and useful criterion for evaluating the water quality performance of a detention basin. The outflow concentrations of total phosphorus were found to be significantly reduced due to basin outlet modifications.

Development of Certification Guidelines for Manufactured Stormwater BMPs

Manufactured stormwater Best Management Practices (BMPs) are becoming an integral part of stormwater infrastructure, as well as a component of wet-weather flow technology. They are commonly used but there are few guidelines regarding the use of these manufactured devices. An ASCE/EWRI task committee was formed in May 2007 to develop guidelines for the certification of manufactured stormwater BMPs. The committee kickoff meeting was held at the EWRI 2007 Congress in Tampa, Florida. At this meeting, the scope of work was discussed, with the consensus being to focus on physical separation of particles for the full spectrum of stormwater-borne non-dissolved solids. Complex issues regarding testing and certification BMPs were identified, and six subcommittees were formed to address these issues simultaneously. These six subcommittees are: (1) Laboratory Testing, (2) Field Monitoring, (3) Scaling, (4) Data Evaluation, (5) Data Reporting, and (6) Maintenance. This paper provides the results of the Task Committee work to date (January 2008), including review of the existing test, verification, and certification procedures and protocols and identification of additional standards development.

Effect of Particle Size on Difference between TSS and SSC Measurements

Three different laboratory methods have been used to quantify the amount of solids contained in the storm water samples. The three methods differ in the sub-sample preparation. In this study, the water samples of nine different particle concentrations over a range from 0 to 1000 mg/L and of seven different particle size distributions over a range from 0 to 1000 microns were prepared and analyzed for the solids concentrations using the three different analytical methods. It was found that the total suspended solids (TSS) concentration measured using EPA Method’s sub-sample pouring procedure was well correlated with the suspended sediment concentration (SSC) measured using the ASTM Method’s whole sample procedure. It was also found that the difference between the measured SSC and the measured TSS-EPA was well correlated with the particle size. The difference was larger as the particle size increased. A regression relationship between the TSS-SSC difference and the particle size was established. This regression relationship could be used to predict TSS-EPA from the reliably measured SSC if the particle size (or the equivalent particle size) is known.

Forewarning model for water pollution risk based on Bayes theory

In order to reduce the losses by water pollution, forewarning model for water pollution risk based on Bayes theory was studied. This model is built upon risk indexes in complex systems, proceeding from the whole structure and its components. In this study, the principal components analysis is used to screen out index systems. Hydrological model is employed to simulate index value according to the prediction principle. Bayes theory is adopted to obtain posterior distribution by prior distribution with sample information which can make samples’ features preferably reflect and represent the totals to some extent. Forewarning level is judged on the maximum probability rule, and then local conditions for proposing management strategies that will have the effect of transforming heavy warnings to a lesser degree. This study takes Taihu Basin as an example. After forewarning model application and vertification for water pollution risk from 2000 to 2009 between the actual and simulated data, forewarning level in 2010 is given as a severe warning, which is well coincide with logistic curve. It is shown that the model is rigorous in theory with flexible method, reasonable in result with simple structure, and it has strong logic superiority and regional adaptability, providing a new way for warning water pollution risk.

The Impacts of Green Infrastructure on Flood Level Reduction for the Raritan River: Modeling Assessment

ABSTRACT The Raritan River has a history of overflowing its banks and causing substantial damage to nearby townships and boroughs. In this study, a hydrological model was developed for the Raritan Basin. The calibrated model was subsequently used to compute the reduction in stream flow as a result of implementing sufficient Green Infrastructure to reduce runoff depth by one inch throughout a chosen Watershed Management Area. In order to simulate the runoff reduction, the curve number corresponding to the reduced runoff was back-calculated. Changing the curve number also changes the lag time and initial abstraction so these values were adjusted accordingly. In terms of discharge, the peak flow would pass from approximately 30,000 cfs to just under 20,000 cfs. The reduction in the stream was then translated to the reduction in the stream water level using the established rating curve. The types of Green Infrastructure that can be used to reduce one-inch of runoff were also assessed, and their costs were estimated as well.

Laboratory Scale Study to Quantify the Effect of Sediment Accumulation on the Hydraulic Conductivity of Pervious Concrete

Pervious concrete systems can reduce storm water runoff, minimize non-point-source pollution, and increase groundwater recharge. However, pervious concrete has the potential to clog, reducing its infiltration rate enough to eliminate these benefits. Pervious concrete clogs when sediment builds up at the surface or within the pervious concrete void matrix, blocking the flow path through the void matrix, thus reducing the infiltration rate. This study measured the effect of sediment accumulation on the hydraulic conductivity of pervious concrete. The resulting data were used to develop a model that predicts the hydraulic conductivity of pervious concrete based on the initial hydraulic conductivity and the amount and type of accumulated sediment.