Rain Rain Flush Away: Evaluating Rainwater Catchment First Flush Volumes

Rainwater harvesting systems often include quality control systems such as a diverted first flush volume to improve the collected water quality. The first flush volume has traditionally been defined as a set volume of rain based on the first 1-2 millimeters of rain that falls on a roof. Diverting a volume of water can be seen as a waste when rainwater is a main source of potable water, sometimes leading to lack of implementation, and thus contaminating the final collected water. Understanding the variability of first flush volume required due to environmental parameters can be used to develop an optimized first flush system. This study evaluated rainwater catchment first flush volumes by assessing the rainwater quality over volume and time. To study these effects, we built a rainwater collection system on a test site in Amherst, Massachusetts. We performed a tracer study with the rainwater collection system to model the first flush volume required to wash out a dissolved contaminant. We collected four rain events using a fractionation first flush design. We measured water quality parameters in the atmospheric rain, first flush, and collection tank samples for each rain event. Our first flush samples resulted in elevated dissolved organic carbon (DOC) concentrations up to 40 mg/L, although there was high variation between the rain events. UV 254, DOC, and conductivity all trended together within each rain event, demonstrating a uniform wash off, of contaminants. Indicator bacteria up to 200 MPN/100 mL within rain event 1 and 2, indicates the need for disinfection if the water is to be potable. The high levels of DOC and SUVA characterization presented a concern for disinfection by-products (DBP) potential if the water were treated with chlorine. Higher intensity storms seem to increase roof wash-off deposition in the first flush. The majority of contaminants washed off in the first flush seemed to originate from roof wet and dry deposition, demonstrating the need for variable first flush volumes. Hydraulic parameters that affect wash-off, such as rain intensity and collection location, also led to varied first flush volumes. Considering these factors in the first flush volume required, could decrease treatment needs, system maintenance, and concern from treatment by-products

Quantifying and contextualizing disinfection byproducts during the Flint Water Crisis: a case study, and framework for broader application

Total trihalomethanes (TTHMs) and other disinfection byproducts (DBPs) have been a concern in Flint, Michigan, in both delivered water and water from home water heaters. Historical TTHM data and DBP sampling results from Flint were combined with models for predicting hot water TTHMs to assess the probability of certain DBP concentrations. Results were compared with hot and cold water DBPs from a water system in Florida. Flint results were used to estimate cancer risk resulting from chronic exposure to hot water TTHMs, and compared to similar risk assessments in other water systems. Results indicate TTHM concentrations decreased in Flint following a return to water from the Detroit Water and Sewerage Department, and were very near the mean value for public drinking water systems in the United States. Measurement of other unregulated DBPs also indicated levels within the typical ranges. Monte Carlo simulations coupled with modeling of hot water TTHMs indicated a low probability of TTHMs exceeding 80 μg/L in Flint in 2016. The estimated cancer risk from exposure to TTHMs in Flint is similar to other areas. The methods used in this work can apply broadly to other water systems to de-escalate perceptions of risk following a water crisis

Laboratory Assessment of Ferrate for Drinking Water Treatment

A laboratory assessment of ferrate (Fe(VI)) for drinking water treatment was conducted, including batch and continuous flow experiments on natural water samples. In batch experiments, ferrate preoxidation enhanced the removal of ultraviolet light-absorbing compounds (UV254; absorbance at 254 nm) by subsequent coagulation in some water samples, while some samples showed no improvement. Ferrate oxidation was not found to have negative impacts on subsequent coagulation. In continuous flow experiments, ferrate preoxidation improved finished water turbidity, UV254 absorbance, and disinfection by-product formation as compared with no preoxidation and to preoxidation with permanganate. However, improvements were similar in magnitude to those achieved by adding the same mass of ferric iron in place of ferrate prior to a formal coagulation step, in one water study. Particulate iron resulting from Fe(VI) reduction was effectively destabilized and removed via coagulation and filtration. Ferrate may be a viable technology for drinking water treatment depending on raw water quality and treatment goals

Comparison of ferrate and ozone pre-oxidation on disinfection byproduct formation from chlorination and chloramination

This study investigated the effects of ferrate and ozone pre-oxidation on disinfection byproduct (DBP) formation from subsequent chlorination or chloramination. Two natural waters were treated at bench-scale under various scenarios (chlorine, chloramine, each with ferrate pre-oxidation, and each with pre-ozonation). The formation of brominated and iodinated DBPs in fortified natural waters was assessed. Results indicated ferrate and ozone pre-oxidation were comparable at molar equivalent doses for most DBPs. A net decrease in trihalomethanes (including iodinated forms), haloacetic acids (HAAs), dihaloacetonitrile, total organic chlorine, and total organic iodine was found with both pre-oxidants as compared to chlorination only. An increase in chloropicrin and minor changes in total organic bromine yield were caused by both pre-oxidants compared to chlorination only. However, ozone led to higher haloketone and chloropicrin formation potentials than ferrate. The relative performance of ferrate versus ozone for DBP precursor removal was affected by water quality (e.g., nature of organic matter and bromide concentration) and oxidant dose, and varied by DBP species. Ferrate and ozone pre-oxidation also decreased DBP formation from chloramination under most conditions. However, some increases in THM and dihaloacetonitrile formation potentials were observed at elevated bromide levels

A Fred Friendly Roundtable

Taking a different approach from the other panels in the Court of Public Opinion Conference, participants in the roundtable role-played their way through a hypothetical (though familiar-sounding) legal issue involving alleged sexual assault by a student athlete, sensitive issues of race and class, and high profile media attention. Moderator Jack Ford, a TV news veteran, assigns roles including defense attorney, District Attorney, reporter, and Chancellor to a large panel, and asks them to examine their various obligations and choices when faced with the unfolding controversy. Questions/themes/discussion topics When and how should university officials publicly address criminal investigations involving students? Do in-house investigations by universities of alleged criminal acts by students affect those students\u27 constitutional rights? How should university officials balance the rights of accused students with the safety of the rest of the student body? Television news\u27s reliance on personality over expertise Public statements by prosecutors and defense counse

White blood cell DNA methylation and risk of breast cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO)

Background Several studies have suggested that global DNA methylation in circulating white blood cells (WBC) is associated with breast cancer risk. Methods To address conflicting results and concerns that the findings for WBC DNA methylation in some prior studies may reflect disease effects, we evaluated the relationship between global levels of WBC DNA methylation in white blood cells and breast cancer risk in a case-control study nested within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) cohort. A total of 428 invasive breast cancer cases and 419 controls, frequency matched on age at entry (55–59, 60–64, 65–69, ≥70 years), year of entry (on/before September 30, 1997, on/after October 1, 1997) and period of DNA extraction (previously extracted, newly extracted) were included. The ratio of 5-methyl-2’ deoxycytidine [5-mdC] to 2’-deoxyguanine [dG], assuming [dG] = [5-mdC] + [2’-deoxycytidine [dC]] (%5-mdC), was determined by liquid chromatography-electrospray ionization-tandem mass spectrometry, an especially accurate method for assessing total genomic DNA methylation. Results Odds ratio (OR) estimates and 95% confidence intervals (CI) for breast cancer risk adjusted for age at entry, year of entry, and period of DNA extraction, were 1.0 (referent), 0.89 (95% CI, 0.6–1.3), 0.88 (95% CI, 0.6–1.3), and 0.84 (95% CI, 0.6–1.2) for women in the highest compared to lowest quartile levels of %5md-C (p for trend = .39). Effects did not meaningfully vary by time elapsed from WBC collection to diagnosis. Discussion These results do not support the hypothesis that global DNA hypomethylation in WBC DNA is associated with increased breast cancer risk prior to the appearance of clinical disease