Tag Archives: sand filtration

Press Spin: Portland, Oregon puts happy face on Bull Run filtration avoidance

Portland, Oregon’s filtration avoidance decision from EPA is certainly good news for the Portland water bureau…..but I’m not so sure it’s good news for the citizens, but they can decide for themselves….

Everything is great in Portland, and it always has been, of course…..by definition.

But, if it walks, talks, and looks like a duck…then its a duck.  And sure enough, this decision is Democrat politics as usual, with Democrat Senator Jeff Merkley taking the credit…Is  he up for re-election?  Click here for the latest spin….

Portland (OR), Parasites, and Politics

Portland’s Bull Run watershed is a beautiful place (click here for prior post)…..A city utility worker gave me and another engineer a tour of it in 1987 (yes, that long ago)….I recall as we drove up the valley stopping at a clearing, the utility worker pointing to an area saying, this is where we would build a filtration plant if necessary.  Of course, the 1986 Safe Drinking Water Act amendments were just passed the prior year, and EPA was just beginning to work on the criteria to determine when filtration would be required (or avoided, as it turned out).  I met an EPA employee with a funny name (Stig Regli), who has since spent most of his career at EPA working on filtration and disinfection regulations.

To make a longer story short, the EPA decision to allow unfiltered water systems (like Portland) to not install filtration has always been a mixture of science and politics.  Back in the late 1980s, it was more about defining the science. Now, 15 years later….the science is pretty well-defined….and a decision to let a city avoid filtration is mostly (if not all) politics.  Democrat governor, democrat mayor, democrat local politicians running for election…. Democrat EPA administrator, President, etc….why cause economic distress  and upset voters….

Cryptosporidium has been detected once again in the Bull Run watershed….and the same arguments to avoid filtration are being made now that have been made for 15 years….same for Portland’s uncovered water storage reservoirs….the more things change the more things (in Portland) stay the same….click here….

Stauber et al 2011: A Cluster Randomized Controlled Trial of the Plastic BioSand Water Filter in Cambodia

C.E. Stauber, E. Printy, F.A. McCarty, K. Liang, and M. Sobsey. A Cluster Randomized Controlled Trial of the Plastic BioSand Water Filter in Cambodia. Environ Sci Technol. 2011 Nov 30.

About half of the rural population of Cambodia lacks access to improved water; an even higher percentage lacks access to latrines. More than 35,000 concrete BioSand Water filters (BSF) have been installed in the country. However, the concrete BSF takes time to produce and weighs hundreds of pounds. A plastic BSF has been developed but may not perform to the same benchmarks established by its predecessor. To evaluate plastic BSF performance and health impact, we performed a cluster randomized controlled trial in 13 communities including 189 households and 1147 participants in the Angk Snoul district of Kandal Province from May to December 2008. The results suggest that villages with plastic BSFs had significantly lower concentrations of E. coli in drinking water and lower diarrheal disease (incidence rate ratio of 0.41, 95% confidence interval: 0.24-0.69) compared to control villages. As one of the first studies on the plastic BSF in Cambodia, these are important findings, especially in a setting where the concrete BSF has seen high rates of continued use years after installation. The study suggests the plastic BSF may play an important role in scaling up the distribution/implementation of the BSF, potentially improving water quality and health in the region.

Click here for full paper (fee).


Chuang et al 2011: Chlorine residuals and haloacetic acid reduction in rapid sand filtration

Y.H. Chuang, G.S. Wang, and H.H. Tung. Chlorine residuals and haloacetic acid reduction in rapid sand filtration. Chemosphere 2011 Nov;85(7):1146-53.

It is quite rare to find biodegradation in rapid sand filtration for drinking water treatment. This might be due to frequent backwashes and low substrate levels. High chlorine concentrations may inhibit biofilm development, especially for plants with pre-chlorination. However, in tropical or subtropical regions, bioactivity on the sand surface may be quite significant due to high biofilm development-a result of year-round high temperature. The objective of this study is to explore the correlation between biodegradation and chlorine concentration in rapid sand filters, especially for the water treatment plants that practise pre-chlorination. In this study, haloacetic acid (HAA) biodegradation was found in conventional rapid sand filters practising pre-chlorination. Laboratory column studies and field investigations were conducted to explore the association between the biodegradation of HAAs and chlorine concentrations. The results showed that chlorine residual was an important factor that alters bioactivity development. A model based on filter influent and effluent chlorine was developed for determining threshold chlorine for biodegradation. From the model, a temperature independent chlorine concentration threshold (Cl(threshold)) for biodegradation was estimated at 0.46-0.5mgL(-1). The results imply that conventional filters with adequate control could be conducive to bioactivity, resulting in lower HAA concentrations. Optimizing biodegradable disinfection by-product removal in conventional rapid sand filter could be achieved with minor variation and a lower-than-Cl(threshold) influent chlorine concentration. Bacteria isolation was also carried out, successfully identifying several HAA degraders. These degraders are very commonly seen in drinking water systems and can be speculated as the main contributor of HAA loss.

Click here to obtain the paper (fee).

Newburgh, New York to become regional water supplier

$26 million will be spent to expand Newburgh’s filtration plant, to reduce dependency of Orange County Water Authority on New York aqueducts. Click here for more…