Journal of Environmental Engineering

The current approach in the U.S. water industry for monitoring Cryptosporidium and Giardia has weaknesses that have contributed to the difficulty of interpreting resulting data. This often leads to potentially significant and dangerous misinterpretation. The purpose of this paper is to summarize information on which the conflicting conclusions on the occurrence and distribution of Cryptosporidium and Giardia have been based. Effort is made to determine the most plausible and supportable interpretation. The objective is to provide a basis for rethinking the current approach to monitoring and management of Cryptosporidium and Giardia in water. The importance of measuring recovery efficiency and reporting measurements of these organisms in terms of concentration to any quantitative application is emphasized. Data presentation to illustrate critical features of organism concentration levels and variation is reviewed. Analysis of major data sets resulting from the U.S. Environmental Protection Agency Information Collection Rule Supplemental Survey (USEPA ICR SS) and the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2) monitoring and other previously published relevant data sets is presented to illustrate key features of Cryptosporidium and Giardia occurrence in surface water and their universal geographic distribution. Current thinking emphatically requires revision.

Using ultraviolet (UV) light to disinfect water has recently become more commonplace, and using computational fluid dynamics (CFD) is increasingly being used to model, optimize, and test UV disinfection reactors. The vast majority of CFD-based UV reactor models assume the steady-state because it was thought that transient phenomena will not lead to significant differences in performance estimates. Recent studies have shown that this assumption may not be valid under certain circumstances, especially when large eddy simulation (LES) is utilized. However, there is no standard methodology to conduct a transient simulation of a UV reactor. The objective of this paper is to propose a standard methodology to model the performance of UV reactors using transient CFD. A simple single-lamp cross-flow UV reactor was used to perform a series of computational experiments to develop a proposed standard methodology for transient simulations, and this method was then verified using two more-complex reactors. The paper examined mesh, time step, initial conditions, and particle tracking to determine model convergence using transient turbulent $k-ϵ$ models. In addition, transient reduction equivalent dose (tRED) was introduced as a means to determine the variability in reduction equivalent dose (RED) over time in a UV reactor. The results showed that although the tRED does not vary significantly for the single-lamp reactor, there is upwards of 10% of variability in the RED for more-complex reactors. The proposed methodology developed in this paper leads to a structured and efficient approach to model UV reactor performance based on transient CFD.

This paper presents a framework for reliable, robust, and resilient system design, addressing the need for acceptable performance not only to be provided under expected conditions, but to be maintained and/or quickly returned to when threats act upon a system. This is achieved through incorporation of multiobjective optimization; assessment of reliability, robustness, and resilience; and filtering and prioritization of solutions at key intervals. The effectiveness of the framework and benefits of its use are demonstrated with a wastewater treatment plant (WWTP) control strategy design problem. The effects of extreme, nondesign loads on highly optimized control strategies have not previously been explored, and it is found in this example that options yielding the greatest improvements under design conditions typically provide poor effluent quality robustness and resilience to influent perturbations. By integrating robustness and resilience, solutions can be identified that meet key performance objectives under design conditions while also minimizing the magnitude and duration of potential failures under extreme conditions. Application of this framework can also yield knowledge of threats to which the system is least robust and/or the requirements most prone to failure under extreme conditions. It is shown here that, when attempting to reduce greenhouse gas emissions by improved WWTP control, decreased influent temperature poses a significant threat and maintaining an acceptable total nitrogen concentration in the effluent under extreme conditions is a key issue.

The primary objective of this study is to develop and evaluate multifunctional open-graded friction course (MOGFC) for use as an in situ treatment technique to remove Cu and Zn from highway runoff. First, the conventional porous pavement, open-graded friction course (OGFC), was prepared with varying air voids. Five different types of adsorbents were selected based on cost, applicability, and availability. Second, MOGFC was prepared by adding different adsorbents into the void of OGFC. A series of laboratory tests were conducted to evaluate the adsorption capacity of the adsorbents and metal removal efficiency of MOGFC. The tests included air void content, permeability, moisture susceptibility of OGFC and MOGFC, batch adsorption study of adsorbents, and metal removal by MOGFC. Results showed that three adsorbents have moderate to high adsorption capacity for copper (Cu) and zinc (Zn) removal from its aqueous solution. With these adsorbents, MOGFC could also considerably reduce metal concentration from the synthesized highway runoff. MOGFC mixtures used in this study were also highly resistant to moisture-induced damage. The results indicated that proposed in situ technique has a potential for field application as a result of its environmental and economic benefits.

Sludge from drinking water treatment plants is usually disposed of in landfill sites as nonhazardous waste. However, a review of the legislation at European, Spanish, and regional levels identifies uncertainty regarding this type of waste. For example, it is unclear whether the drinking water sludge can be sent to inert landfill sites, which would be less expensive, or whether it could be reused for other purposes. According to Article 5 of Spanish Law 22/2011 on waste and contaminated soil, various physicochemical and biological parameters must be determined before alternative uses can be established. At present, sludge from drinking water treatment plants is wrongly associated with sludge from wastewater treatment plants. In this study, parameters of the sludge produced in drinking water treatment plants that may lead to a new waste status for the same are analyzed. The principal problems that may limit its reuse are its low organic matter and high silica contents.

Bromide concentrations increased significantly in the Monongahela River in Pennsylvania in 2010–2011. These increases led to increases in trihalomethane (THM) and haloacetic acid (HAA) and increased bromination of these disinfection by-products (DBPs) in drinking water at plants on the Monongahela River. This study presents a statistical simulation model to evaluate the effect of the increasing source-water bromide on THM formation and speciation and analyzes the changing risks (by using cancer slope factors) in treated water from 2010 to 2012. Even very low bromide concentrations were associated with increased cancer risk from ${\mathrm{THM}}_4$. ${\mathrm{HAA}}_9$ increased with increasing source-water bromide as well, but the bromination factors of regulated ${\mathrm{HAA}}_5$ decreased. Increasing source-water bromide in the Monongahela River favored bromine incorporation in ${\mathrm{THM}}_4$ rather than ${\mathrm{HAA}}_9$. Collection and analysis of bromide and THM and HAA data for the development of similar bromination factor regression analysis and human health risk assessment for regionally relevant elevated bromide in source water can be used in other areas experiencing or expecting similar source-water changes.

Column and vessel experiments were conducted to investigate changes in mobility, leaching, and availability of lead (Pb) and cadmium (Cd) in contaminated soil (Santo Amaro Municipality, Bahia State, Brazil) after treatment with different sources of phosphate followed by assessment of phytoextraction by vetiver grass [Vetiveria zizanioides (L.)]. Columns were filled with contaminated soil and ${\mathrm{KH}}_2{\mathrm{PO}}_4$ (T1 treatment), reactive natural phosphate fertilizer (NRP) (T2 treatment), ${\mathrm{KH}}_2{\mathrm{PO}}_4$ mixed with NRP (T3 treatment), and untreated contaminated soil used as reference soil (T0 treatment). After 60 days, soil samples were collected from each column every 10 cm in depth and vessel experiments were initiated by planting vetiver grass. After 90 days, Pb and Cd were extracted from the soil and from the plant tissues using diethylenetriaminepentaacetic acid (DTPA) and nitro-peroxide extraction, respectively. Metal mobility was assessed using two methods: the toxicity characteristic leaching procedure (TCLP) and the sequential extraction proposed by the Community Bureau of Reference (BCR). The most effective treatment in reducing mobility, availability, and toxicity was T1 (${\mathrm{KH}}_2{\mathrm{PO}}_4$). With regard to reduction of bioavailability to plants, T1 treatment was more effective for Pb than for Cd. According to the BCR method, Cd was more soluble and had higher mobility than Pb.