Journal of Environmental Engineering

Accurate chemical dosing in water treatment plants is imperative to ensure optimal efficiency of flocculation and disinfection. Design algorithms, calibration techniques, and standardized components are presented for a linear flow orifice meter (LFOM) and a linear chemical dose controller (LCDC). These coupled systems allow water treatment plant operators to easily and reliably set and maintain the desired doses of coagulant and disinfectant. The combined system adjusts the chemical flow rate automatically in response to changes in plant flow rate to maintain the target chemical dose. The LFOM maintains a linear relationship between height of water in the entrance tank and plant flow rate. A lever and float are used to create a direct relationship between the plant flow and chemical flow produced by the LCDC. A linear relationship between head loss and chemical flow in the LCDC is created by using the major head loss through a small diameter tube to control the chemical flow rate. Experimental tests are described that minimize minor losses and verify performance of the LCDC.

Although recycling depots can promote recycling, their spatial distributions significantly affect efficiency. Despite the ability to locate depots throughout a region by minimizing total service distance, residents in sparsely populated areas may have to travel long distances to a depot. Although increasing the number of depots can reduce these distances, the associated costs increase. This study develops six optimization models based on the three objectives of minimizing maximal service distance, maximizing the service ratio, and minimizing the number of depots for district-based, district-open and nondistrict scenarios. Three factors, service distance, district equity, and service ratio, are used to assess the performance of models. A case study of 16 districts is utilized to demonstrate the application of the models. Minimizing the number of depots under the nondistrict scenario achieves a good service ratio with short service distance using fewer depots than other models. The proposed models will facilitate efforts to determine an appropriate spatial distribution of recycling depots.

A numerical model is used to estimate the service life and clogging of gravel leachate drainage layers with a filter separator layer, such as those used in municipal solid waste landfills. A filter separator layer between the waste and the drainage layer is shown to reduce the leachate strength entering the gravel drainage layer and to extend the time that it takes to clog the drainage layer to the point when the leachate level exceeds the maximum design value (the service life). The filter layer is shown to have a far more significant effect in extending the service life when pea gravel ($d_g=6\mathrm{mm}$) is used in the drainage layer, and less effect when coarse gravel ($d_g=27\mathrm{mm}$) is used in the cases examined, although most of the benefit of a filter separator layer was achieved by using a 3-mm-thick needle-punched nonwoven geotextile. This geotextile may be sufficient for many practical purposes that are similar to those examined. The results from modeling leachate collection systems with filter separator layers subjected to both constant and variable leachate strength show that the characteristics of the leachate entering the drainage layer can substantially affect the service life of the drainage layer, and that high-strength leachate entering the systems for a limited time early in the life (acid phase) of a landfill can greatly reduce the service life of the leachate drainage layer.

Free-drift batch reactor experiments using calcite (limestone, ${\mathrm{CaCO}}_3$) were used to study fluoride removal through precipitation as fluorite (${\mathrm{CaF}}_2$) from solutions with concentrations reflective of an industrially contaminated site. The influence of ${\mathrm{CO}}_2$ partial pressure (${\mathrm{pCO}}_2$), stirring rate, and fluoride concentration were investigated in this paper. Equilibrium modeling shows that in wastewaters with high fluoride concentrations ($\sim \mathrm{2,000}\mathrm{mg}/\mathrm{L}$), the flux of ${\mathrm{CO}}_{2(\mathrm{g})}$ to ${\mathrm{CO}}_{2(\mathrm{a}\mathrm{q})}$ could not keep up with the consumption of ${\mathrm{CO}}_{2(\mathrm{a}\mathrm{q})}$, resulting in an initial disequilibrium with experimental pH reaching equilibrium quickly, while fluoride removal lagged. Increasing stirring rate significantly decreased the extent of disequilibrium and the time at which the ${\mathrm{CaCO}}_3$-fluoride-${\mathrm{CO}}_2$ system attained equilibrium due to the increased rate of transport of dissolved ${\mathrm{CO}}_2$ to the ${\mathrm{CaCO}}_3$ surface, and simultaneously the rate of transport of the dissolved ${\mathrm{CaCO}}_3$ to the bulk solution. Optimal fluoride removal occurs at ${\mathrm{pCO}}_2{\sim 10}^{-0.52}$ [30% (mol% ${\mathrm{CO}}_2$)] with 96% of the initial $\mathrm{2,000}\mathrm{mg}/\mathrm{L}$ fluoride load removed in less than 80 min with a stirring rate of 300 revolutions per minute. Increasing ${\mathrm{pCO}}_2$ to $\sim 100$ (100% ${\mathrm{CO}}_2$) resulted in very little gain, less than 2%, in fluoride removal, or in the time required to reach equilibrium and therefore significant remediation cost savings can be obtained by using ${\mathrm{pCO}}_2$ 30% when compared to 100%.

A novel method for irrigation with saline water uses a polymer membrane, formed into a tube, to treat and distribute the water simultaneously. The flux of water across the membrane occurs by the process of pervaporation, during which a phase change from liquid to vapor occurs. Thus, water arrives in the soil in the vapor phase. The experimental results presented in this paper demonstrate that, contrary to previous assumptions, soil vapor flows are a significant transport mechanism during pervaporative irrigation in dry soils. The soil water sorption properties affect the rate of condensation in the soil, which in turn affects both the water distribution in the soil and the loss of water vapor to the atmosphere. The flux from the tube becomes limited by high humidities adjacent to the external surface of the membrane. Thus, enhancing condensation in the soil or increasing diffusion through the soil increases flux from the system. These findings highlight the need to consider how plants might interact with water supplied in the vapor phase.

Concerned about environmental pollution and health safety risks, waterborne polyurethane (WPU) was introduced in place of conventional binders in preparing an active carbon polyurethane foam, active carbon WPU foam (ACWPU foam), through two sequential steps. The scanning electron microscopy and wettability tests showed that the WPU-based process was effective for achieving a higher active carbon content, enhanced pores’ wall roughness, and improved hydrophilicity of the foam, which was explained by infrared spectroscopy. Adsorption behavior of the ACWPU foam for phenol in aqueous solutions was investigated by batch experiments. The results showed that the maximum removal capacity of phenol ($\mathrm{5,000}\mathrm{mg}/{\mathrm{dm}}^3$ foam) with $0.389{\mathrm{dm}}^3\mathrm{foam}/\mathrm{L}$ of sorbent was observed at $100\mathrm{mg}/\mathrm{L}$ at pH 7. Removals of more than 85% occurred in 2.5 h, and the loading half-time was calculated to be only 26.77 min. In addition, adsorption kinetic data were described by a pseudo-second-order equation and the equilibrium data fitted very well with the Langmuir and Temkin models. Further, the ACWPU foam could be fully recycled via 0.01 M NaOH. In general, WPU as an environmentally friendly binder had excellent application in preparing ACWPU foam. Meanwhile, this foam should be a promising adsorbent in the recovery of phenol.

The accurate speciation analysis of arsenic is a serious concern for water quality monitoring programs. Because the preservation of sample integrity until analysis is one of the most important aspects of speciation, this study aims to compare the performance of four different sample preservation methods under diverse conditions of sample quality. Natural samples with different characteristics were collected into the following containers to study their effectiveness: (1) standard high-density polyethylene bottle with no preservative; (2) empty, sterile Vacuette tube with no preservative; (3) sterile tripotassium ethylenediaminetetraacetic acid (K3EDTA) Vacuette tube with K3EDTA additive; and (4) empty, sterile Vacuette tube with added hydrochloric acid (HCl). Known concentrations of arsenite [As(III)] were also added to each container to monitor the oxidation of As(III) to arsenate [As(V)]. The results revealed recovery ratios exceeding 95% in all containers with sterile vacuum conditions. In particular, the K3EDTA Vacuette tube yielded a recovery very close to 100% of the spiked As(III), which is known to rapidly oxidize to As(V). Overall, collecting the sample into a container under sterile vacuum conditions and using a universally accepted preserving agent such as EDTA or HCl significantly improved the preservation of the original species distribution in the water matrix studied, compared to sampling without the use of preservation methods. After validation by future research, these sterile vacuum tubes can possibly be utilized for collecting and storing samples for the routine speciation analysis of other elements such as selenium, chromium, and antimony.

Enhanced biological phosphorous removal (EBPR) from wastewater has been successfully used for more than three decades and is considered to be an environmentally friendly wastewater-treatment process. Biologically, this process is realized by incorporation of phosphate as polyphosphate (polyP) granules in activated sludge bacteria. Important groups of bacteria responsible for P removal have been identified, but the full microbial diversity involved in this process is still unknown. This paper reports on the microbial composition of activated sludge communities in eight wastewater-treatment plants (WWTPs) with different sizes and modes of operation. The polyphosphate accumulating organisms (PAOs) within this complex biocenosis were identified by fluorescent dye staining and classified by in situ hybridization techniques. Of the bacteria in the aerobic basin, 5–13% contained polyP granules. In addition, flow cytometry was used to quantify PAOs after tetracycline staining and to separate these cells. The phylogenetic affiliation of the sorted PAOs was identified by cloning and sequencing. Both workflows showed similar outcomes. The majority of PAOs in all plants were Betaproteobacteria (22%), Actinobacteria (21%), and Alphaproteobacteria (12%), with differences in the relative abundance. In addition, Bacteroidetes (12%) were detected in the clone libraries, especially Haliscomenobacter, which should be considered further with regard to its influence on the EBPR process. The denaturing gradient gel electrophoresis analyses of sorted PAOs revealed a diverse community composition of Betaproteobacteria, Actinobacteria, and Rhodocyclales in the WWTPs. PAOs were present in EBPR and non-EBPR WWTPs, and no correlation in their abundance and phylogenetic composition to the mode of operation was revealed. This study shows that specific PAO communities existed in the various WWTPs, probably favored by the respective wastewater composition, including so far unvalued PAOs species, but their active contribution in the EBPR process remains to be investigated.

The objective of this study was to assess lead release in a pipe rig system that was disinfected with either chloramines or free chlorine. The study was carried out using pipe loops and copper pipe rigs that had lead solder, which provided the only source of lead. The water quality of the treated water had a low alkalinity ($<5\mathrm{mg}/\mathrm{L}$ as ${\mathrm{CaCO}}_3$), neutral pH, and low hardness ($<5\mathrm{mg}/\mathrm{L}$ as ${\mathrm{CaCO}}_3$). However, the study used a corrosion control program that consisted of dosing with 0.8-mg ${\mathrm{PO}}_4/\mathrm{L}$ of zinc orthophosphate and controlling the pH to 7.3, that was consistent with the corrosion-control program operated in the host water treatment plant. Key findings from the study confirmed that chloramines would result in lead release under the current corrosion-control program, whereas free chlorine was not as compromising. Lead concentrations were approximately an order of magnitude lower in the free chlorine system than the chloramine systems. In this study, chloramines with a target residual concentration of $5\mathrm{mg}/\mathrm{L}$ released $382\mathrm{\mu g}/\mathrm{L}$ and $49\mathrm{\mu g}/\mathrm{L}$ following stagnation times of 24 h and 30 min, respectively. Furthermore, chloramines with a target residual concentration of $1\mathrm{mg}/\mathrm{L}$ resulted in a lead release of $73\mathrm{\mu g}/\mathrm{L}$ and $14\mathrm{\mu g}/\mathrm{L}$ following a stagnation time of 24 h and 30 min, respectively. By comparison, the pipe rigs that were dosed with a free chlorine target residual concentration of $1\mathrm{mg}/\mathrm{L}$ had lead concentrations of $12\mathrm{\mu g}/\mathrm{L}$ and $2\mathrm{\mu g}/\mathrm{L}$ for the 24-h and 30-min stagnation times. This project demonstrates that care needs to be taken when evaluating secondary disinfectants, particularly for those water systems having a low dissolved inorganic carbon concentration.

Storm-water control measures (SCMs), also known as storm-water best management practices (BMPs), are increasingly being used to mitigate the impacts of development and restore the hydrologic cycle. This paper presents a three-tiered monitoring plan that can be used to determine the effectiveness of structural, nonproprietary SCMs in the Northeast United States. The monitoring plan offers three levels of monitoring: high, medium, and low. This 1-2-3 approach is common in environmental monitoring. The monitoring protocol integrates hydrologic, water quality, and ecological factors and recommendations for equipment with the level of monitoring. The monitoring plan is then applied to a rain garden on Villanova University’s campus in Villanova, Pennsylvania, and a cost analysis of the different monitoring levels is provided.

A characterization scheme based on landfill leachate chemical signatures could support studies of leachate evolution over time and liner performance, and help confirm or disprove potential leachate contamination of groundwater. Wide variations in single constituents across time, sites, and site practices, and inconsistencies related to common bivariate measures suggest a robust, multivariate analysis could be useful. A subjective analytical comparison of soluble salts has been developed and supports graphical depictions of multiple samples. The hypothesis is that leachates with similar chemistry form clusters, and this was tested using a data set of 652 samples from 26 distinct liner systems collected from a Long Island landfill over more than 20 years. Most (75%) of diagrams were classified into three general leachate groupings that associated with the kinds of wastes received in the particular landfill module (90% if early leachate results are not considered).

In this present study, strongly cationic coagulants were prepared by modifying chitosan with 3-chloro-2-hydroxypropyl trimethyl ammonium (CTA). The coagulation properties of this cationic chitosan (chitosan-CTA) were systematically examined in laboratory and pilot scale studies. At the laboratory scale, the effects of coagulant dosage, temperature, initial turbidity of untreated water, pH, and salinity were investigated by a jar test using kaolin suspension as synthetic water. Compared with several conventional coagulants, chitosan-CTA showed a lower dosage requirement of approximately $0.05\mathrm{mg}/\mathrm{L}$, but higher turbidity removal efficiency of approximately 93.3%. Moreover, raw water from the Zhenjiang part of the Yangtze River in China was used as test water for further investigation on a pilot scale. The influences of dosage, sedimentation time, and mechanical mixing rate on the coagulation properties were studied by an orthogonal test and the optimal experimental conditions were obtained. The dosage of coagulants was $1.1\mathrm{mg}/\mathrm{L}$, sedimentation time was 20 min, and the mechanical mixing rate of the first triple coagulative sedimentation tank was 200 rpm in this case. The effect of the substitution degree of CTA on the coagulation properties was also investigated at the laboratory and pilot scales. Above all, the coagulation experiments indicated that the cationic chitosan-based coagulants showed good coagulation performance in turbidity removal.

The separation of waste printed circuit boards (WPCB) has been a bottleneck in WPCB resource processing. In this study, the separation of WPCBs was performed using dimethyl sulfoxide (DMSO) as a solvent by dissolving polymer materials. Waste printed circuit boards of $1–1.5{\mathrm{cm}}^2$ in size were placed in DMSO at 60°C for 45 min. A metallographic microscope verified that the WPCBs produced the delamination. When the incubation time was increased from 45 to 210 min, polymer materials in WPCBs were dissolved by DMSO, and copper foils and glass fibers in WPCBs were separated completely. When the size of the WPCBs was increased from 1–1.5 to $2–3{\mathrm{cm}}^2$, the temperature of separating completely the copper foils and glass fibers in WPCBs increased from 60 to 90°C, but the separating time decreased from 210 to 90 min. The liquid photo solder resists (LPSR) were still adhered to the copper foils. The used DMSO was treated by rotary decompression evaporation, and the regenerated DMSO and solid residues were obtained. This new technology offers a new way to separate valuable materials from WPCBs.

Car wash runoff is known to be a pollution source to surface water bodies. Many groups hold car-washing fundraisers unaware of pollution issues associated with car wash runoff. This preliminary study investigated whether rain gardens are an appropriate management practice for reducing car wash pollutants, specifically surfactants. The concentrations of total phosphorus (TP), total suspended solids (TSS), and surfactants were measured in car wash runoff before and after treatment in three rain garden mesocosms. Mean TSS and surfactant effluent concentrations were significantly lower than the car wash runoff with TSS reductions ranging from 84 to 95% and surfactant reductions ranging from 89 to 96%. The removal efficiencies for surfactants were not enough to reduce concentrations below literature-based values for aquatic toxicity. Mean TP effluent concentrations were higher than the car wash runoff with increases ranging from 197 to 388%, although the increase was not statistically significant. This project demonstrates the potential for using bioretention to reduce pollutants associated with car wash runoff and using car wash events to educate the public about watershed protection.