Water Journal : Water Journal August 2012
refereed paper governance water AUGUST 2012 59 second process monitoring and control capabilities. Speed-of-light ultraviolet (UV) light disinfection can be monitored; computational fluid dynamics (CFD) helps optimise treatment controls; and instrumentation allows rapid response to treatment upsets. Treatment is being reduced from days/hours of chlorination, to minutes of ozonation, to a split-second of UV. Because of these trends, USEPA regulations continually push US utilities to install advanced operations and treatment technologies to meet increasingly stringent requirements. The challenge in water treatment and the protection of water quality is that there are no absolute barriers to pathogens for large-scale, regional distribution of piped water. As the world population grows and healthcare improvements allow for populations of the aged and various other immunocompromised to grow, there may be increased sensitivity to low levels of pathogenic organisms in drinking water. The result of the increased capabilities of treatment technologies coupled with continued possiblity of acute waterborne disease outbreaks: Imposed regulation for treatment techniques for improved removal and/or inactivation of pathogens. Epidemiological Health effects research is identifying increasing numbers of chemicals -- both prolific in our environment and formed through chemical reactions during water treatment -- that negatively impact public health. New studies are increasingly being used to develop an ever-changing contaminant candidate list (CCL) for compounds that should be regulated to their 'de minimus' cancer risk level. On- going work in epidemiology will also be aided by advances in science that allow laboratories to more easily detect these compounds. The result may be: Increased number of compounds to be regulated, as well as the potential for imposed treatment techniques to remove greater amounts of natural organic matter in order to reduce DBP formation. Consumer expectations and confidence One of the most unpredictable and variable impacts on regulation may be consumer confidence and expectations. An example of how consumer confidence could rapidly change includes the July 1998 detection of Cryptosporidium oocysts in Sydney-area source water (Sinclair et al., 1998). This led to Sydney water being labelled as unsafe in July, then again in August. Although there were no illnesses recorded, a 'boil water' notice was issued. If consumers perceive tap water is not safe to drink, customer confidence will need support either from regulation or self-directed utilty programs. One challenge with the ADWG and WQMP dynamic is that self-directed utility research is not rewarded. Instead, utilities that conduct extra sampling and/or research may actually be 'rewarded' with increased regulation depending on their findings. This is a barrier to utilities' ability to conduct research and development, proactively increasing consumer confidence. If it were, instead, an environment that encourages innovation, consumer confidence could be kept in check while other benefits such as increased treatment efficiency and decreased operating cost may be realised. If consumer confidence decreases: The regulatory environment may change, becoming increasingly stringent. Table 7. Comparing ADWG and USEPA disinfection by-product requirements. Disinfection By-Product (DBP) Disinfectant Responsible 2011 ADWG Value mg/l 2011 USEPA Value mg/l Bromate Ozone (O3),+ 0.02 0.01 Chlorate Chlorine dioxide (ClO2),+ NV 0.8CA Chlorite ClO2,+ 0.8 0.8 Halogenated acetic acids * Chloroacetic acid Chlorine (Cl2) and Chloramines (NH2Cl) 0.15 Summed Value Less than 0.030 or 0.060 Dichloroacetic acid 0.1 Trichloroacetic acid 0.1 Chlorophenols 2-chlorophenol 0.3 NV 2,4-dichlorophenol 0.2 2,4,6-trichlorophenol 0.02 Cyanogen chloride ** 0.08** 0.200** Formaldehyde O3, Cl2, ClO2 0.5 NV n-Nitrosodimethylamine (NDMA) NH2Cl 0.0001 CA Total organic carbon Precursor # NV tt Trichloroacetaldehyde Cl2, NH2Cl 0.02 CCL Trihalomethanes (sum total) Cl2, NH2Cl 0.25 0.08, 0.04## Specific UV absorbance (SUVA) Precursor # NV 2 L/mg-m NV No value set for regulation or guidance at this time. CCL Not currently regulated by USEPA, but on the Contaminant Candidate List 3 (CCL3) for potential future regulation. + These compounds are DBPs and they are formed during the production and storage of bulk liquid chlorine. CA State of California (US) has certain requirements that are more stringent than USEPA regulations, which include the following: - NDMA public health goal = 0.000003mg/l = 3 nanograms per litre, ng/l (the 10-6 CRL) - NDMA notification level = 0.00001mg/l - NDMA response level = 0.0003mg/l (level where source should be removed from service, 10-4 CRL) - Chlorate notification level = 0.8mg/l - SUVA Specific ultraviolet (UV) absorbance = Water absorbance of UV light at a wavelength of 254 nanometres, nm (UV254), divided by the total dissolved organic carbon (DOC). tt A treatment technique is in place that requires a certain percentage removal of either total organic carbon (TOC), which is based on the measured ratios of alkalinity and TOC, or the calculated SUVA (if SUVA is >2.0 L/mg-m). The purpose of this treatment technique is to reduce the formation potential of DBPs and aid in protection of the retic system. * USEPA does not regulate acetic acids separately, but combines several into a sum of five, which includes dichloro-, trichloro-, monochloro-, bromo- and dibromo- (acetic acid). USEPA is in the process of evaluating the risk of several additional acetic acids and including them into the current summed regulation. ** ADWG lists "as cyanide" while USEPA lists "as free cyanide". # SUVA and TOC are not DBPs, but they measure precursors that directly impact DBP formation during chemical disinfection. ## Most utilities are required to meet the 0.08/0.06 mg/l guidelines (THM/acetic acids species respectively); however, certain conditions do require the sum of each total to be less than 0.04/0.03 mg/l (for total THMs/acetic acids, respectively).
Water Journal September 2012-1
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