Water quality impacts of bridge stormwater runoff from scupper drains on receiving waters: A review.

This article provides insight into the environmental significance of bridge deck stormwater runoff from scupper drains on receiving water bodies through a review of over eighty sources of information including research and review articles, technical reports and government websites. This article discusses sources and impacts of stormwater pollutants and presents potential methods for predicting impacts of stormwater runoff on receiving waters from highways and bridges. Records of similarities and possible differences between highway and bridge deck stormwater runoff are provided, and the significance of scupper drains as points of runoff discharge from bridges is discussed. Factors that influence bridge deck stormwater runoff quality include the location of the bridge, dimensions of the bridge deck, composition of the road surface, age of the bridge, design and maintenance of the drainage system, traffic volume, and intensity and frequency of rainfall events. Several pollutants of concern are discussed, such as heavy metals, polycyclic aromatic hydrocarbons, solids, nutrients, oil, grease, polychlorinated biphenyls, and perfluorinated compounds. This review also discusses available methods for treatment of bridge deck runoff and the challenge of applying these methods for treatment of bridge deck runoff, as compared to treatment of highway runoff. Finally, this article considers the application of the stochastic empirical loading and dilution model (SELDM), a joint product of the U.S. Geological Survey and the Federal Highway Administration, to predict and assess the potential effects of runoff on receiving waters.

Perchloroethylene (PCE) oxidation by percarbonate in Fe(2+)-catalyzed aqueous solution: PCE performance and its removal mechanism.

The performance of Fe(2+)-catalyzed sodium percarbonate (SPC) stimulating the oxidation of perchloroethylene (PCE) in groundwater remediation was investigated. The experimental results showed that PCE could be completely oxidized in 5 min at 20 °C with a Fe(2+)/SPC/PCE molar ratio of 8/8/1, indicating the effectiveness of Fe(2+)-catalyzed SPC oxidation for PCE degradation. Fe(2+)-catalyzed SPC oxidation was suitable for the nearly neutral pH condition, which was superior to the conventional Fenton oxidation in acidic condition. In addition, the investigations by using hydroxyl radical scavengers and free radical probe compounds elucidated that PCE was degraded mainly by hydroxyl radical (HO) oxidation in Fe(2+)/SPC system. In conclusion, Fe(2+)-catalyzed SPC oxidation is a highly promising technique for PCE-contaminated groundwater remediation, but more complex constituents in groundwater should be carefully considered for its practical application.

Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment.

Effect of recycling activities on the heating value of solid waste: case study of the Greater Vancouver Regional District (Metro Vancouver).

Two main goals of the integrated solid waste management system (ISWMS) of Metro Vancouver (MV) include further recycling of waste and energy recovery via incineration of waste. These two very common goals, however, are not always compatible enough to fit in an ISWMS depending on waste characteristics and details of recycling programs. This study showed that recent recycling activities in MV have negatively affected the net heating value (NHV) of municipal solid waste (MSW) in this regional district. Results show that meeting MV's goal for additional recycling of MSW by 2015 will further reduce the NHV of waste, if additional recycling activities are solely focused on more extensive recycling of packaging materials (e.g. paper and plastic). It is concluded that 50% additional recycling of paper and plastic in MV will increase the overall recycling rate to 70% (as targeted by the MV for 2015) and result in more than 8% reduction in NHV of MSW. This reduction translates to up to 2.3 million Canadian dollar (CAD$) less revenue at a potential waste-to-energy (WTE) plant with 500 000 tonnes year(-1) capacity. Properly designed recycling programmes, however, can make this functional element of ISWMS compatible with green goals of energy recovery from waste. Herein an explanation of how communities can increase their recycling activities without affecting the feasibility of potential WTE projects is presented.