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Top 3 Stages Of Water Treatment And How To Select Suitable Control Valves 

Water is a precious resource that’s vital in any industry. For this reason, water treatment facilities are essential in ensuring that this Universal Solvent is put through processes that will guarantee its purification for safe usage. 

On account of this, there’s a need to be aware of the proper methods that can be used towards water treatment, and what specific types of control valves will work best for these mediums. 

3 Basic Differential Stages Of Water Treatment 

1.Mechanical Stage

The mechanical stage or physical stage is considered the “pre-cleaning” phase. Think of it as Stage 1 of water treatment wherein untreated wastewater is put through mechanical filters in a screening plant. Afterward, a sieve drum acts as a large filter to separate debris from the wastewater. 

A variety of coarse and fine screens that differ in centimeters to millimeters, and in gaps, are interchanged as filtration continues. Water flows through these screens at differing speeds until most of the coarse materials therein are removed. 

Now pre-purified, the water is streamed through a sand collector. This sedimentation tank furthers the extraction of coarse materials that were not removed in the initial screen-filtration. Sand and small coarse organic elements are then sifted and collected. The three classes of collectors include long-sand, aerated long-sand, and round-sand.

2.Biological Stage

Wastewater contains a plethora of organic substances, from partially-to-completely undigested food items, a slew of waste groups, pathogenic microorganisms, chemicals, and toxins, to heavy metals. 

The treatment itself is a practice that hinges on the use of typical cellular methods through small organisms and other bacteria to break down and eliminate organic waste materials. Through its process of microbial decomposition, flocculation will take place so that organic matter will naturally be separated from the solution itself. 

Biological Stages

Aerobic Water Treatment

The keyword to remember about aerobic treatments is that they warrant the presence of “oxygen”. Oxidation ditches, spray aeration, aerobic tanks, trickling filters, and the like belong under this category. 

With oxygen as the main agent for treatment, organic matter is turned into bacteria and fungi (microbial biomass) for further decomposition and carbon footprint reduction. 

Anaerobic Water Treatment 

“Anaerobic” is defined as “without oxygen”. Thus, this water treatment works in the absence of oxygen. Sewage and liquid waste (a.k.a. effluent) that are released into bodies of water such as rivers and seas go through this systemic approach. 

Additionally, anaerobic treatments are known for being able to convert waste into energy. Through its resource-recovery and energy-recovery approach, anaerobic bacteria convert organic pollutants into biogas. Biogas, then, can be utilized in fuel operations. It plays a crucial role in assisting in the conversion of resources into Net-zero energy, leading to carbon neutrality. 

In other words, it decreases or even eradicates, the need for fossil fuel consumption. So, it’s safer for the environment and may slow the pace of climate change.

Anoxic Water Treatment 

Nitrate is a common groundwater contaminant. And this third type of biological water treatment has to do with denitrification so that nitrate in wastewater is brought to a state of degradation, and is converted into an energy source (oxygen).

3.Chemical Stage 

In this stage, water is placed under chemical processes to accelerate sterilization. These are employed to comply with certain disinfection standards. Said processes include (but are not limited to) chemical coagulation, chemical and advanced oxidation, ion exchange, absorption, precipitation, flocculation, and neutralization. 

Moreover, specialized chemicals like chlorine, sodium chlorite and hypochlorite, and hydrogen peroxide are activated in the treatment itself to enhance the purification procedure and ensure wastewater is decontaminated. 

Chemical Coagulation And Flocculation: Particles are destabilized. The first group transports negative electric surface charges and the other, coagulants that are positively charged. The latter decreases negative electric surface charges to allow flocculants (particle-clumping agents) to bind with larger ones. Hence, making it easier to remove said bound-particles through sedimentation. 

Chemical/ Advanced Oxidation: Oxidizing agents are introduced so that pollutants are structurally altered into safer compounds. Following this, advanced oxidation through stripping, or absorption eliminates excess organic byproducts of chemical oxidation. 

Ion Exchange: “Hard” water is softened by the replacement of calcium and magnesium ions (the cause for water hardness) with sodium ions. 

Absorption: Activated carbon binding takes place so that remaining soluble elements are accumulated for effectively and easier eradication.

Precipitation: Leftover solubles are dissolved and transformed for precipitation to occur. When this happens, material concentration is lessened. 

Neutralization And Stabilization: Oxidants are cast into the sludge to decelerate biological cultivation. This also results in the deodorization of the mixture. 

Control Valves: An Overview

Based on its name alone, a control valve “controls” the streaming and fluidity of water by diversifying the flow channel dimensions such as temperature, liquid degree, and pressure. Actuators are used to direct these motions through the opening and shutting down of control valves. 

Ensuring the use of suitable control valves in water treatment cycles will equate to more efficient and cost-effective operations. The control and direction of the movement of water as it goes through treatment can be stabilized with the right valve types. Below is a rundown of the three major valves that should be present in water treatment facilities.

Types Of Control Valves

Butterfly Valve 

What differentiates butterfly valves from other classifications is that it has a connecting disc and shaft that expedite rotation. Known to be included in the cluster of quarter-turn valves, it follows that it can either open or close when swiveled in a rotating manner, a quarter of the way through (90-degree rotation). 

It’s a vital valve to put into position not only because of its capacity to provide excellent shutting off but also because of its ability to regulate flow-rate and throttle. A gearing instrument or a similar manually-handled wheel is its common avenue of operation. 

Furthermore, butterfly valves are a great option for frequent usage because of their high-capacity characteristic. 

How To Select The Suitable Butterfly Valve In Water Treatment 

Pressure Drop 

The traditional butterfly valve was limited to low-pressure drop. However, with recent innovations to this valve, high-pressure drops are now possible, too. This is a feature you’ll want to take into consideration. It may serve as a practical means for you to tell if the valve is of an older model or a more modern one. 

Corrosion Resistance

In parallel to every nominal valve dimension, a butterfly valve has an adjacent shaft diameter for each one. This is because these valves can withstand varying torques, pressure conditions, and friction. 

Therefore, you’ll need to assess its degree of corrosion resistance to ascertain that it will hold out well against said volatile movements. You can do this by checking its pressure rating. The rating maximum is usually at 35%. 

Ball Valve 

Ball valves are a classification of control valves wherein a spherical plug can be found at its core, and this sphere has a central aperture for mounting. It’s through the rotation of the “ball” that flow is controlled and accordingly offers a tight shutoff mechanism. 

That being said, ball valves supply very little flow resistance. They are not to be used for throttle streaming as this will give rise to the valve incurring abrasions, and ultimately, leakage, even when the valve is shut down. 

Still, it’s a good choice for workings that require prompt valve opening and closing since it can speedily isolate piping segments. Plus, they’re convenient to automate and are economical in cost compared to other valve types. 

How To Select The Suitable Ball Valve In Water Treatment 

Opening-Closing Speed 

Quick-opening and closing are what defines a quality ball valve. Check that its quick-acting motion is seamless whether in a half or full position. You won’t have to inspect other functions because it’s restricted to simply “opening” and “closing”. 

Size And Weight

Due to the fact that ball valves are limited to moderate throttling, they’re comparatively small in size and are lightweight


In addition to its being compact, a butterfly valve is able to moderate flow control so that it gives out a very low noise. Another property to take into consideration when inspecting this valve class.

Globe Control Valve 

Globe control valves have a moveable disc and an immobile ring seat that commonly comes in a spherical shape. It starts, stops, and regulates fluid flow in a linear mode, thereby making it have a precise path. This implies that its flow control provides an equal percentage per operation.

Another advantage of globe control valves is that their pressure limitations have a broad scope of 1480 psi to 1500 psi (pound-force per square inch). Even its minimum-to-maximum temperature faculty has a wide range as well. On the other hand, as long as pressure drop isn’t a controlling variable, globe valves can be maximized for most types of liquids, gases, and corrosive matter.

How To Select The Suitable Globe Control Valve In Water Treatment 

Differential Pressure Limit

According to experts, the differential pressure limit of a typical globe valve shouldn’t go beyond 20% of 200 psi. Only if you’re scouting for specialized trimmings will you find designs that exceed that 20%. Then again, if there’s no need to, then sticking to the first is acceptable. 

Control, Drop, And Duty 

Because they are utilized expressly for their level of precision, flow regulation or control, pressure drop, and duty are the three key factors to examine in selecting suitable globe valves. This is to avoid any malfunctioning once activated for its operating condition. 


Though we’ve mentioned only three of the main types of control valves, it’s important to note that understanding what kind of valve will suit particular treatment requirements is a must. In this manner, it will be easier for you to align which control valve to purchase and utilize for efficient water treatment.

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