In water treatment systems it is often important to measure the rate at which water is flowing through the system. Data from flow measurement devices can be used to control chemical dosing, set pump speeds, control filter loading rates, inform maintenance programs, and other tasks necessary for operation of a water treatment facility or on key components such as Degasification and Decarbonation systems or Biological Odor Control Systems. As with most types of instrumentation, there is an array of technologies that can be used for the task, each one with various strengths and optimal applications. For modern electronically controlled systems, the most common types of flow sensors used are axial turbine flowmeters, paddlewheel flowmeters, differential pressure / orifice plate flow transducers, and magnetic flowmeters. This article will briefly discuss the technology and features of each of these types.

A turbine flow meter,

consists of a tube that contains supports to hold a multi-bladed metal turbine in the center. The turbine is designed to have close clearance to the walls of the tubing such that nearly all of the water is made to flow through the turbine blades as it travels through the pipe. The turbine is supported on finely finished bearings so that the turbine will spin freely even under very low flows. As the turbine spins, a magnetic pickup located outside of the flowmeter housing is used to sense the tips of the turbine blade spinning past the pickup. An amplifier/transmitter is then used to amplify the pulses and either transmit them directly or convert the pulse frequency into an analog signal that is then sent to a programmable controller for further use elsewhere in the system. One advantage of a turbine flowmeter is that the electronics are separated from the fluid path. The magnetic pickup is the only electronic component, and it is installed outside of the turbine housing, reading the presence of the turbine blade tips through the wall of the sensor body. In clean water applications, this can be advantageous because the magnetic pickup can be replaced if needed without removing the turbine from service. However, the turbine itself covers most of the pipe area and creates back-pressure in the system, requiring increased pumping energy to move a given amount of water. In Industrial Water Treatment or Filtration Treatment,  turbines can also easily become fouled or jammed if they are used to measure water or other fluids with entrained solids, algae or bacteria cultures which cause significant accumulation, or corrosive chemical components that can degrade the turbine bearings.

One of the largest consumers of energy in the US are the water and wastewater treatment plants.

Because of the need for large horsepower pumps and blowers a municipal water and wastewater treatment plant consumes a tremendous amount of kilowatt hours of electricity. The cost of the energy is factored into the “cost of production” of the treatment of water or wastewater and the “rate base” charge is increase accordingly to the consumer.

Does Renewable Power Work in a Water Treatment Plant?

Because solar energy is “space intensive” you do not see a lot of solar power being deployed across the USA at water treatment plants. This is in our opinion a mistake and most likely the decision was made back when solar power output was much lower. Now with increased efficiency of the solar panels and a decrease in production cost it makes tremendous sense to revisit the use of Solar energy for offsetting the operational cost of a water treatment plant or wastewater treatment plant operation.

Providing solar energy for specific pieces of process equipment is also a viable option when you consider deploying solar energy. As an example, to operate a Degasification tower or Decarbonator utilizing 10 350 watt solar panels will generate 3500 watts during peak day light hours and enough to offset the cost of smaller horsepower blower motors. If the solar panels are configured as a canopy they can also provide a nice shade or protection barrier above the piece of equipment if installed outdoors as most packed column towers are located outside.

What about other forms of renewable energy do they work?

At water treatment or wastewater treatment facilities? The use of Co-generation has been around for many years at Wastewater plant facilities waste water treatment plant. A cogeneration unit is a combination “Generator” to produce power and a “Thermal” energy source to produce heated water. The water can be used domestically or can be used to produce chilled water with the help of a Chiller system. The waste water treatment plant  provides a critical component by producing gases such as “Methane” which can be utilized as a fuel source for the cogeneration unit. Water treatment plants do not produce methane gases or other combustible forms of gases so you normally do not see Co-generation units deployed at a Water treatment facility.

Over the last 2 decades there has been vast development and improvement of wastewater technologies in regards to the water treatment processes that have been driven by both need and governmental regulations. Today, municipalities and Countries are recognizing the need to recycle wastewater into drinking water and in locations such as the Caribbean and other foreign nations the wastewater to drinking water industry is more of a “must” than a choice.

Water treatment in the Caribbean offers distant challenges for water professionals. During the design process an engineer must examine multiples aspects of a potential project to ascertain the most cost effective and most sustainable approach. Geographic location can become a major variable during the design selection process. As an example, if the location is remote, too often the shipping of liquid chemicals becomes a challenge as well as the training of operators to safely handle the chemicals during normal operations. The ability to secure trained operators may impact the success or failure of a water treatment process such as membrane separation, reverse osmosis and degasification or decarbonation not to mention odor control.