Disinfection by-products (DBP) formation is an issue in communities that depend on surface water for drinking.

All along the rocky Canadian Shield, in Alaska, and in the North-east USA, it is difficult to drill wells, so smaller communities often rely on surface water that tends to be heavy with dissolved organic materials. Heavy chlorination is required and that can lead to high TTHM (trihalomethane) and HAA(5) (haloacetic acid) concentrations in the treated water. Studies have shown that TTHMs and HAA(5)s may be carcinogenic and their presence has also been linked to miscarriages.
Providing safe drinking water in small communities is made more difficult when skilled labour required to run what amounts to a miniature chemical plant is neither readily available nor affordable. In addition, the tightening of drinking water regulations in North America with introduction of Stage 1 of the Disinfection By-Products rule in the US, and new regulations in Ontario and Quebec Provinces in Canada make running conventional chemical water treatment plants even more challenging.
Until promulgation of the Stage 1 D/DBP Rule, small surface water systems in the US have been exempt from federal limits on TTHMs and HAA(5)s in their treated water. Compliance was required by November 2003. In Canada, new regulations are in place in Ontario and may soon be introduced in other Canadian Provinces, pushing small, rural communities to seek solutions that effectively remove organic matter prior to chlorination.
Fortunately, a new nanofiltration membrane filtration process, now available in North America from PCI Membrane Systems, Inc., Milford, OH, promises effective water treatment without high capital costs or heavy labour requirements.
The Fyne Process, as it is called, was first used in Scotland, UK in 1992, and has become the water treatment technology of choice for rural communities with organic-laden surface water from lakes or rivers as the water source. The first few North American installations have been very successful
The Fyne Process uses nanofiltration membranes to retain undesired dissolved organic materials (mostly humic and fulvic acids) that, after chlorination, produce undesired disinfection by-products. The membrane system also reduces undesirable levels of iron and other metals, which may also be found in these types of surface water.

Waterborne pathogens

The membrane also holds back waterborne pathogens, microbes and viruses. The systems are simple and automated enough to allow unattended operation, with intervention on no more than a weekly basis for routine operation and maintenance. The system can be monitored continuously and remotely when an outside telephone line is available.
The first Fyne Process plant went into Scotland in 1992 and there are now over 30 PCI installations running or on order with the three Scottish Water Authorities. Small systems use proprietary half-inch tubular membrane filters, which can be used with minimal pre-filtration and which can be kept clean by periodically passing a foam ball down the length of the tubes. Larger systems are more economical when fitted with spiral nanofiltration membranes, although this configuration requires up-stream pre-filters to remove suspended solids down to 10microns. While a tubular membrane system may only require chemical cleaning 3 - 4 times per year, spiral systems must be chemically cleaned more frequently.
The first Fyne system went into North America in February 2000 at Chapel Island First Nation in Nova Scotia, Canada, and has been running full-time ever since. A second, smaller system began operating in June, 2000, at The Tl'azt'en Nation community of Middle River in British Columbia. In addition, a Fyne Process membrane filtration plant installed to process highly organic surface water in Barrow, AK, was tested and verified under the US Environmental Protection Agency Packaged Water Treatment Plant Verification Program.
Chapel Island is a small First Nation Community located east of Halifax, Nova Scotia. The plant was installed with a rated capacity 26.2gal/min (143m3/day), with a 20-year projected demand of 56gpm/305m3/day. The new installation replaced a small packaged water treatment plant using coagulation and filtration technology that required expansion and significant refurbishment.
Raw water is taken from a shallow lake with typical TOC levels of 8mg/l and colour normally in the 40 - 100TCU range. The intake is taken through a 3mm screen and piped to a sump under the water treatment plant room. There is no additional filtration or treatment prior to the membrane filter. Reject water, which is merely a more concentrated form of raw water that has had no chemicals added to it whatsoever, is fed back to the lake. When a chemical clean is necessary, these chemicals are sent by separate drain to a wastewater treatment lagoon where sludge from the conventional flocculation and clarification package plant (now removed) had previously been sent.
The system was competitively bid, and although initial capital costs were higher, the Fyne Process was chosen from a variety of different treatment methods because of its lower overall life cycle cost. Running cost savings are realised as the Fyne Process uses no chemicals in the production of the water and requires significantly less attention allowing hard pressed maintenance staff to attend to other community demands. The system is also designed to allow simple plant expansion to meet future projected needs of the community.
Additional capacity can be added easily as and when required to meet the actual needs of the community. The plant has been run above its design capacity since installation, producing on average 155m3/day, operating each day for 21.4hrs on process. It has been cleaned only twice in the 12months since start up and was to have been cleaned for the third time around its first anniversary of start up. The plant did experience a significant increase in pressure over a short period, when a cleaning of the inlet works created an influx of sediment into the raw water sump.
Although the sediment remained in the inlet line for a number of days, the membrane plant continued to produce its rated volume of water albeit at a higher operating pressure until its second partial clean a month after the incident. This experience only served to prove the resilience of the Fyne Process to upsets in raw water quality, for whatever reason.
The Tl'azt'en Nation community of Middle River is a small village located on a river northwest of Prince George, British Columbia. An isolated community two hours from the nearest town, the site is a prime candidate for the benefits of the Fyne Process. The plant operated initially as a six month pilot to test its suitability for operation in a remote community. An engineering firm, CH2M Canada, monitors performance of the system for the Department of Indian and Northern Affairs Canada. At the end of the pilot period it was decided to purchase the unit.

Filtration modules

The Fyne plant, which has a design capacity of 5.8gal/min (22l/min), operates with 6PCIC10 filtration modules. Raw water is drawn from the nearby river. Lift pumps provide water to the plant with a 2.5mm screen at the intake.
The Fyne plant continues to operate in a heated and ventilated 40ft container, complete with membrane wash tank, chlorine dosing and contact tanks, and 1100gal storage. Reject from the plant (which, as noted, is just raw water with a slightly higher organic content) is sent to a sump tank overflowing back to the river. To protect the environment, a separate tank is used to contain washing chemicals that can then be taken away by tanker truck. Plant control is almost identical to that installed at Chapel Island, with data also logged continuously. Unlike Chapel Island, however, it is not possible to dial into the system, as no telephone link exists to the site. Regular analysis of feed water and filtrate is also made.

Performance of the system has been very similar to Chapel Island. Middle River runs at higher pressure due to proportionately lower membrane area installed. Corrected pressure rose at a constant rate until the first membrane clean, which was scheduled for four months after first operation of the plant. This clean was not entirely effective and a second clean was performed shortly after to establish if any significant irreversible fouling was occurring. Cleaning concentrations and duration were increased for the second clean which then returned the plant to within 96percent of its early normalised flux. In other words, the cleaning was successful.
The US EPA has verified that the 'Fyne Process' water treatment system from PCI Membrane Systems, works better than just fine. A study published as part of the EPA's Environmental Technology Verification (ETV) Program verifies the performance of a Fyne Process membrane filtration plant tested on high organic laden surface water in Barrow, UK. The plant was able to remove significant levels of organics - precursors to disinfection by-products like trihalomethanes (THM) and haloacetic acids (HAA) - producing water that easily met the Disinfection By-Product standards set by the EPA's stringent Stage 1 D/DBP Rule. Barrow's untreated water had an average total organic carbon (TOC) level of 15mg/l and with moderate turbidity. Over the 57 day test period, the average TTHM concentration was reduced from 535µg/L in chlorinated raw water to just 31µg/L in water chlorinated after nanofiltration in the Fyne Process test plant. Average HAA(5) concentrations were reduced from 398.4µg/L to just 6.2µg/L. The membrane system also reduced UV254 absorbance, total organic carbon, and turbidity - measures of water colour and clarity - by 97.5percent, 95.4percent, and 98.3percent, respectively.

A clear choice for maintenance

For treating small surface-water flows (1000gal/day and upwards), the easy-to-clean tubular membranes of the Fyne Process make it the better choice over higher-maintenance spiral membrane systems, says PCI North American General Manager David Pearson. "Using tubular nanofiltration membranes, the Fyne Process can be run with minimal operator intervention, requires little to no source-water pretreatment and extremely infrequent chemical cleaning.
"Spiral membranes require frequent chemical cleaning or expensive pre-treatment on these organic waters, and then there is the issue of cleaning-chemical disposal," explains Pearson. "But the surface of the tubular membranes of the Fyne Process can be kept clean with foam balls, so the system doesn't need any real maintenance for several months."
This, automated, 'foam ball' cleaning cycle periodically forces foams balls through the tubular membranes, loosening accumulated material and removing it from the system. PCI offers complete water-treatment packages, including containerised plants, and can also provide remote monitoring of system performance.
PCI Membrane Systems is a world leader in the application of membrane filtration systems. In addition to tubular membranes for liquids containing suspended or colloidal materials, PCI also supplies spiral-wound or hollow fibre membranes for clean solutions, and ceramic membranes for high chemical compatibility and thermal resistance. With its own membrane manufacturing facility and in-house R&D group, PCI is able to engineer filtration materials and systems that exactly match the customer's application requirements. Installation, commissioning, training, and technical support services are also available.
With the success of these systems in North America, Sanitaire's PCI unit expects that the Fyne Process, with its particular advantages for remote, small communities will be accepted across North America as the process system of choice, just as it has been in Scotland, UK.
For treating small surface-water flows (1000gal/day and upwards), the easy-to-clean tubular membranes of the Fyne Process make it the better choice over higher-maintenance spiral membrane systems.