Many people are interested to know about the water in Belize and how our water plant works. Today I am giving you a followup to my previous post on that (see link below) as both Shirlee and Ann wanted to share their experiences from the Consolidated plant tour. If the technical side of our water system is an interest to you, I highly recommend you book yourself in for a Consolidated Water tour with Dee Dillon. You can reach him at firstname.lastname@example.org, 226-3845, Mobile – 610-4860.
Not only is he informative but he makes it fun learning about how the San Pedro water system works.
CWBL Tour by Shirlee Arnould
I have had the pleasure of touring the plant on three separate occasions. It lasts for about an hour and takes you from start, (the wells from where the water is extracted) to finish (the storage tanks). Actually, the tour starts in the office/control room which is chalk full of monitoring equipment.
The equipment inside the plant is very noisy so Dee is very good at explaining the process in the quieter areas as he leads the tour. He gives a bit more detail than what he did in the previous post Ever wondered about Belize water and how the plant works? and it is very cool to see all the equipment in action as he’s speaking. He does a great job and says it’s one of his favorite things to do.
Based on my own observances of how the water is cleaned at Consolidated Water, I use tap water for coffee, cooking, ice, washing and brushing my teeth. I drink bottled water because I live fairly close to the plant and it is quite chlorinated when it gets to my tap so it doesn’t taste that great. Also, it may be very clean when it leaves CWBL, but what happens while it travels through the pipes to the northern part San Pedro – well I just don’t know. 🙂
Consolidated Water Tour by Ann Kuffner
General Manager – Clifford “Dee” Dillon, P.E. Took his position on the island in 2011. Dee used to work in California, for Metropolitan Water District (one of the largest retail water districts in the USA). He later worked for the State Water Contractors in Sacramento, where the Peripheral Canal was a very interesting long-term planning project. Both were two very visible, high-quality water districts.
Dee manages six Belizean staff members. They are very good employees who take pride in their work.
Consolidated Water was started by Americans and is headquartered in Grand Cayman. Their main business is seawater treatment using Reverse Osmosis membranes. They have water treatment plants in several locations worldwide, including Belize (1), Grand Cayman (7), Bahamas (3), British Virgin Islands (2), and soon a larger plant in Mexico.
Consolidated Water is totally separate from Belize Water Service. They provide and treat water to BWS tanks. BWS distributes the water to the town.
In 2013 they hit capacity. They could barely produce enough water in April/May of 2013. There was an increase of 12% water usage on the island, from 2012 to 2013. That gives us a pretty good idea of how much tourism and island growth has expanded. The water usage only dropped in October and November last year. There has been so much increased demand on the island.
The southern well has a good limestone aquifer connection, so the water is clear. The northern well has lesser water quality and is the color of tea when extracted. Consolidated uses string filters before their R.O. filters. The pore size of the string filters removes up to 5-micron particles. In 2010 they had problems because nearby dredging stirred up silt that traveled through the aquifer and plugged the filters. The sediment that filtered into the aquifer was smaller than 5 microns, so it plugged the membranes.
Every so often they get an algal bloom when the weather is hot. Additional treatment is required during those limited times.
The Reverse Osmosis (RO) Process
They extract seawater from two wells that were drilled with augers that go down to 40-45′. Water is removed with submersible pumps.
The seawater is at about 33,000 ppm salt when it enters. The RO membrane filters result in two streams. The treated stream has about 300 ppm of residual salt. Some other minerals are retained, such as magnesium chloride. It is important to leave some minerals and salts in the water, both for health, and to reduce corrosiveness that occurs if the water has no salts.
The RO Membranes themselves have pores of .54 microns (really, really small) and it takes from 950-980 psi to push clean water through them and leave most of the salt behind.
The seawater is pre-filtered with four string filters. Then there are 12 R.O. membrane vessels per treatment train. Six membranes are added to each case. That is a total of 2x12x6 = 144 R.O. modules installed. Both trains operate at once when at full capacity. Prior to string filters, there is an 8 stage pump to increase the water pressure to 600 psi, which is further boosted to 980 psi by a turbine driven by the brine.
They have two separate trains of reverse osmosis modules, each with 12 modules. They produce 190 gpm each at maximum capacity. The membranes are made of thin film polyamide, manufactured by Dow Chemical Company. They can last up to five years, depending on the treatment and the water they are exposed to. Three years is more common on the island. They are single pass filters.
The chemicals used to clean the membranes, to remove organisms/bacteria and foulants are a proprietary mix learned after years of testing and experience. They are constantly experimenting with new chemical combinations to optimize the cleaning process. So far it has been working. If it is proven to work long-term, it could extend the length of the membranes, which are costly, ($500US + each). They are also adding more R.O. membranes and trying to improve their cleaning processes to better remove iron and sulfate scale with special chemicals, so membranes function better and last longer.
When the water exits the filters they pass it through an H2S stripping tower to remove the naturally occurring sulfur smell. So if you smell sulfur near the site, it is from water treatment, not wastewater treatment.
Next, they add the Chlorine, before sending the treated water to the large tank. Residual chlorine is in water when it travels through water lines, to be sure bacteria can’t survive and don’t regrow in the distribution system.
Any iron that appears in the water, at the tap, is not from Consolidated Water. It is most likely from metal fittings in the distribution system or your own plumbing system.
The brine that comes out of the R.O. filters is re-injected into the aquifer, at 135′ below the surface. Any remaining chemicals in the brine end up cleaning the injection lines.
There is an emergency generator in case of a hurricane. It can be 24-48 hours before water production is restored for anything Category 3 or less. BWS’s lines impacted by a hurricane would also need to be replaced or repaired as well in order for water service to be restored.
Since parts mostly come in from the USA, they keep spare parts on hand, for all equipment.
Consolidated Water operates 24 hours per day. Everything is monitored electronically but mostly operated by hand.