Water Treatment Plant

PlantWTP including an effluent treatment plant: There are three different sections in a WTP: a pretreatment (PT) plant, a posttreatment or demineralized water (DM) plant, and a waste treatment or effluent treatment (ET) plant. The ratio of numbers of analog to digital measurement is near unity, and because at present there is hardly much difference between the DCS and PLC, so the selection of control could go either way. However on account of many sequential controls pertinent to each of the exchanger units in a DM plant and effluent plants (and cost also), the PLC is preferred as the control system. It has been found that in some cases, a number of PLCs are utilized for a total WTP plant. Also, some smaller units use PLCs with SLC (Section 4.3). A WTP encompasses everything from a raw water pump house to a DM storage tank, and the location of the pretreatment plants is far from the DM plant control room, where normally the main PLC and operator station are placed for control and operation. Sometimes it is better for pretreatment plants to have a separate PLC with remote I/Os for a raw water plant. Again, a chlorination plant is almost an independent plant and may be controlled by a micro PLC. Depending on plant size and configuration, the ET plant may be an elaborate system involving many I/Os, so a separate PLC with communication to the main system may be economical. Finally, all these PLCs may be integrated or linked to have relevant data available at the DM control room. Alternatively, these may be achieved by deploying remote I/Os and/or via a fieldbus to reduce cable cost. In a nutshell, there is a need to have an integrated LAN with a soft link or fieldbus. In terms of automation, there are differences in control systems deployed for PT, DM, and ET. In pretreatment plants, there will be a number of pumps, and their automatic selections and associated logics are major issues. Also, there will be a few measurements such as flow measurement by a Parshall flume. For a large power house, there may be a large number of pumps and valves, so these automatic selections are not very simple and a dedicated PLC may be a better option. Similarly, in a DM plant, there will be sequential operation of solenoid-operated valves for backwash and regeneration for the exchanger units. Regeneration can be done in various modes such as DP across an exchanger, time-based, or a conductivity-based system, so the PLC needs to take care of such selections. As in a DM plant, there are controls for chemical handling (for example, brine tank automation). The sequence control may be fully automatic, semiautomatic, or manual. A PLC in a DM plant needs to handle many analog parameters (for example, pH, Cond. analyzer) for monitoring and for modulating control (for example, degasser control) also. Therefore, the trending of parameters is important. In case of small DM plants, the use of a local dedicated sequencer is not uncommon. Selection of the IP rating for a PLC and local enclosure is quite important as the environment is very corrosive. In these plants, local operation of a few drives is common, for example, the clariflocculator agitator, so local panels with operator interface and a link to the LAN may have to be considered.

Industrial RO plant

Industrial RO plant is a revolutionary technology proved to be a boon for industrialists, housing societies, hostels & restaurants and hospitals by providing clean and purified water which can be used for production as well as consumption purposes. They are highly recommended as they efficiently remove up to 99% of dissolved solids, contaminants or impurities from the water making it safe, pure, and clean.

What is RO Plant?

An Industrial RO (Reverse Osmosis) system is a manufacturing plant which purifies contaminated water through the process of reverse osmosis. The Industrial RO Water plant requires a variety of pre-treatment methods such as softening, dechlorination as well as antiscalant treatment. After the pre-treatment process, a high level of pressure is used to send water through a semipermeable membrane which retains all the contaminants from the water and passes pure water through. Depending upon the concentration of salts and contaminants in the water, energy levels are determined. On average, an industrial Reverse Osmosis plant needs 6 kilowatt-hours of electricity to purify 1 cubic metre of water.

Why do we need an RO Water Plant?

RO system helps to purify the contaminated water which can be used for a variety of purposes such as:

• • Drinking water
• • Desalination
• • Wastewater treatment
• • Concentration of contaminants
• • Reclamation of dissolved minerals, etc.

What is Reverse Osmosis process?

Reverse Osmosis (RO) is an effective process where you desalinize as well as remove all the impurities by putting it under pressure through a semipermeable membrane which purifies the water. To thoroughly understand the reverse osmosis process, let first understand the osmosis process: Osmosis is a natural process where a liquid, such as water, passes through a semipermeable membrane which allows some molecules such as water to pass through, but other molecules such as salts and organic matter are unable to easily pass through the membrane structure. The flow of liquids through a membrane occurs naturally to even out the salt concentration between the two solutions. Liquid flows from the low concentrated solution, such as freshwater, to a high concentrated solution, such as seawater. When the direction of liquid flow is reversed, it is called reverse osmosis. This process of reverse osmosis is embedded in the Industrial RO plant. By pressurizing the high concentrated solution, such as seawater, we are able to force water molecules in the reverse direction from the salty seawater side through the semipermeable membrane to the freshwater side. A semipermeable membrane is often made of cellulose acetate, polymethacrylate and polyamides. We call it a semi-permeable membrane because it allows only the solvent or the water but does not allow the ions, minerals or the colloidal matter present in the water.

Let us understand the process of the RO System.

In the RO Water plant, there are two compartments; one which contains high concentration water (for e.g. seawater) and the other compartment contains low concentration water (pure water). Both the compartments are separated by the semi-permeable membrane. When we apply a high level of pressure on the high concentration water compartment, the water moves into the low concentration compartment through the semipermeable membrane. The water we collect out is called reverse osmosis water.

How does RO Plant work?

An Industrial RO plant contains the following parts:

• • Raw water pump
• • Activated carbon filter
• • Sand filter
• • Dosing pump
• • Micron Filter
• • High-pressure pump
• • RO membrane
• • Reject line
• • Recycling line
• • RO product line
• • Control Panel Box