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Industrial Wastewater Treatment Systems

Industrial Wastewater Treatment Systems

Eatay Pomeranz
Technology Manager // 10 Aug. 2021
Eatay has over thirty years of experience in filtration and water treatment in the agriculture and industrial sectors

First, let’s understand the term wastewater. Wastewater is downstream contaminated water from any domestic, industrial, or commercial activity and has various characteristics depending on its source. With constantly increasing environmental regulations, wastewater streams need to be treated.

The role of wastewater treatment plants (WWTP) is to treat wastewater to level of final effluent as the solids are removed. In most cases, the treatment is required to remove suspended and dissolved contaminants.

In this blog post, we will concentrate on industrial wastewater treatment systems.  Virtually every industry uses water in the manufacturing process – electric power plants, the food industry, mining, steel and iron industry, oil and gas extraction, pulp and paper, to name just a few.  Industrial wastewater requires treatment to remove contaminants (such as, phosphorus and heavy metals) before reuse or discharge to the environment and treatment generally involves physical, chemical and biological processes. Here are some examples of industrial wastewater. In many cases it will be a combination of several of the below:

  • Filter backwashing water: contains trapped particles from filter beds
  • Boiler blowdown water: contains impurities concentrated by steam generation
  • Brine water: waste streams from water softening, ion exchange, or RO
  • Wet scrubber effluent water: contains pollutants removed from smokestack combustion gases to meet air quality regulations
  • Acid mine drainage water: water resulting from dewatering coal and metal mines
  • CIP water: water containing chemicals for cleaning industrial equipment and piping
  • Industry process water: clean water (not potable) used for many of the various industrial processes.

Industrial Water Treatment Systems – How Do They Work

Industrial wastewater treatment systems need to efficiently cope with an array of variable conditions, such as flow, contamination, water chemistry, chemical volume modifications, and the requirements of water effluent.

Determining the elements and technologies included in an industrial wastewater treatment system depends on the source of the wastewater, specific treatment requirements and local regulations, but a typical system will include the following processes and the role of each in wastewater treatment (also see the diagram below):

  • Collection Sewers: collecting all of the industrial wastewater from the various production processes
  • Pumping System: distributing the wastewater to the subsequent treatment processes
  • Bar Screening: removal of coarse debris, sand, rocks, etc.
  • Chemical and pH Adjustment: adding chemicals to bring the pH levels to an optimal level
  • Primary Treatment Tank 1: open settling tank
  • Primary Treatment Tank 2: open aeration tank
  • Secondary Treatment: clarifier
  • Disinfection: chlorination or UV treatment
  • Tertiary Treatment: final polishing stage, filtration to reduce the TSS and BOD levels
  • Sludge Dewatering / Decomposition: drying the sludge for disposal or reuse as fertilizer according to strict environmental regulations

(click the image to enlarge)

Wastewater Treatment Systems – Contaminants Removal

Varying quantities and concentrations of contaminants are found in wastewater, depending on the water source.  The role of the wastewater treatment process is to remove them, making the water safe for discharge back into the environment or for reuse purposes. Here is a partial list:

  • High Biochemical Oxygen Demand (BOD): BOD is the level of organic matter that can be biologically oxidized and broken down into smaller molecules
  • Oils & grease
  • Total suspended solids (TSS)
  • Metals (zinc, iron, lead, nickel)
  • Pathogens: bacteria, viruses, fungi, or other microorganisms
  • Nitrates and phosphates
  • Other inorganic contaminants

Industrial Wastewater Treatment System – The Processes:

Treatment systems for wastewater, cooling towers blowdown and raw water are typically the most essential. Following is an explanation of each treatment process:

Wastewater Treatment Processes

By treating industrial wastewater, the resulting effluent water is discharged back into the environment, reused for industry or routed to a municipal wastewater treatment plant.  In addition, the treatment process reduces water loss and waste, enables savings on energy production and prevents costly fines if handling the industrial wastewater is not in compliance with local regulations.

Several technologies may be used in industrial wastewater treatment systems, depending on the contaminants in the water and other specific treatment requirements. Below are the typical processes for treatment:

  • Clarification: This is usually the last stage of the secondary treatment, for removing suspended solids, metals and silica. Tanks with added chemicals along with coagulation, flocculation, sedimentation and then filtration are needed to remove finer particles.
  • Disinfection: When biological contamination is present, a disinfection treatment for neutralizing or removing pathogens is crucial to protect against any health issues. There are regulations regarding acceptable levels and the process is constantly monitored to make sure that the WWTP meets the standards.
  • Softening: If there are high quantities of calcium/magnesium/other metals, this step will be used to reduce the hardness of the water. The softening process can be done by means of ion exchange, RO or chemical settling where lime/lime soda will be used to raise the pH levels.
  • Specialized Processes: As earlier mentioned, industrial wastewater varies greatly from facility to facility and specific treatment is sometimes required. We go into more detail in the “Additional Options for Wastewater Treatment ” section.
  • Distribution: The last step to the process is returning the industrial wastewater to the facility where it can be reused or discharged back into the environment or sewer system, depending on local regulations.

Treatment Processes for Cooling Towers Applications

These systems protect the components of cooling towers from damage caused by contaminants found in the water, for example, iron, silica, chlorides, TDS, TSS, calcium, bicarbonates, sulfates and more. Feedwater that is not treated properly will cause added expenses due to increased downtime and maintenance, decreased productivity and the need to replace costly equipment.

Treatment Processes

  • Makeup Water Intake: Water lost due to evaporation, leaks and drainage while flowing through the cooling tower system needs to be replenished with makeup water. Makeup water has various sources (municipal water supply, industry wastewater, raw water), and treatment is sometimes needed.
  • Filtration: There is usually at least one filtration system for removing sediment and organic materials and turbidity reduction. This treatment process protects equipment and efficiently prevents fouling and the need for excessive and costly maintenance.
  • Softening: Softening resins or membrane softeners may be helpful if the makeup or source water has a high level of hardness. This treatment can improve the cooling tower water use efficiency.
  • Chemicals: Chemical treatments might include adding one or more of the following: scale inhibitors (protecting pipes and other equipment), corrosion inhibitors (neutralize acidity), biocides/algaecides (reduce biological contaminant growth).
  • Side-stream Filtration: Cooling tower systems are most efficient when heat transfer surfaces are clean. As cooling towers operate outdoors, they are vulnerable to dirt and debris which can cause scaling, fouling, and microbiological activity. Filtration of the side stream flow provides a cost-effective solution to increase system efficiency, reduce corrosion rates, maintenance costs and chemical use.
  • Post-treatment: Depending on conditions at the industrial facility, there are several options for post-treatment. If water quantity is limited and/or if a considerable amount of water is needed for the cooling process, blowdown water with reverse osmosis or ion exchange treatment and reuse may be selected.

Treatment Processes for Raw Water Applications

These systems are for pretreatment and improving the quality of the source water to maximize the efficiency and operation of specific applications, for example, cooling tower or boiler feedwater, process water and potable water. Treatment aims at protecting downstream equipment from damage that may be caused by source water contaminants.

Treatment Processes

  • Intake: Water entering an industrial facility either by gravity or pumping or both, flows through grates or screens, trapping large debris that would otherwise pass into the systems.
  • Clarification: There are multiple steps in the process for removing suspended solids:
    1. Coagulation
    2. Flocculation
    3. Sedimentation
    4. Media filtration
  • Disinfection: When biological contamination is an issue, a disinfection treatment may be used either by applying chemical or physical disinfectants and/or membrane filtration.
  • Lime Softening: If there are high quantities of minerals/sulfates, this step will be used to reduce the hardness of the water and lime/lime soda will be used to raise the pH levels.
  • Ion Exchange: Ion exchange treatment involves channeling the water through a sodium charged resin for removing the hardness.
  • Distribution: After the water is treated, it is directed to other areas of the facility for reuse.
  • Membrane Filtration: MF, UF and NF membranes are not as expensive as they once were and as a result, their use is more widespread and in some cases, membranes have even replaced “traditional” industrial wastewater treatment methods.

Treatment Processes for Boiler Feedwater Applications

These systems protect parts and/or piping from damage that may be caused by contaminants found in boiler / makeup feedwater, such as dissolved and/or suspended solids, dissolved gasses, hardness and organic matter. Boiler feedwater can cause a range of issues if not properly treated, which in turn may lead to increased downtime, maintenance and energy usage. Boiler feedwater treatment usually consists of all or some of the following processes:

Treatment Processes

  • Makeup Water Intake: Water loss due to steam consumption, condensation return and leakage needs to be replenished with makeup water. Makeup water has various sources (treated municipal water or treated raw water).
  • Filtration: There is usually at least one filtration system for removing sediment and organic materials and turbidity reduction. This treatment process protects equipment and efficiently prevents fouling and the need for excessive and costly maintenance.
  • Softening: For trapping and removing hardness from the stream, ion exchange is often used by utilizing softening resins (usually a strong acid cation).
  • Dealkalization: Boiler feedwater can suffer from alkalinity, causing foaming and carryover in the boilers and pipe corrosion. This water is treated with either strong anion ion exchange or weak acid ion exchange preceding degasification to remove bicarbonate, sulfate and nitrate ions thereby reducing the pH levels.
  • RO and NF: These types of membrane filtration are applied when treating boiler feedwater, but can be beneficial in removing bacteria, organics, salts, hardness, and silica.
  • Primary Ion Exchange: When dealing with high-pressure boilers or large water volumes, deionizers sometimes replace membrane filtration. Ion exchange delivers higher yields and quality.
  • Deaeration / Degasification: The boiler system’s makeup water and condensate are merged and degasified – dissolved oxygen and carbon dioxide are removed from the stream to prevent the damages of corrosion.
  • Polishing: Sometimes polishing is required, based on boiler requirements. Polishing technologies usually consist of offsite regenerable or mixed bed ion exchangers or electrodeionization.
  • Distribution: The last step to the process is piping the boiler feedwater to the boiler for heating, to produce steam, after which it can be mixed with makeup water that has been treated and reused.

Specialized Wastewater Treatment Processes – Additional Options

  • Activated Sludge Process (ASP): Air or oxygen added to primary or industrial wastewater, combined with organisms to develop a biological floc.
  • Sequencing Batch Reactor (SBR): Oxygen is blown through a mixture of activated sludge and wastewater, reducing the organic matter and measured as BOD and COD.
  • Sequencing Batch Bioreactor (SBBR): A newer development for improving the SBR process that accelerates the aeration stage for treatment of wastewater with a lower hydraulic retention time (HRT). This is done by combining SBR with a biofilm reactor.
  • Membrane Bioreactor (MBR): A combination of a membrane filtration like MF or UF and the activated sludge process, commonly used in municipal and industrial wastewater treatment.
  • Moving Bed Biofilm Reactor (MBBR): The biological process for industrial and municipal wastewater treatment for BOD removal, nitrification and denitrification with the smallest footprint.

Amiad’s Industrial Water Treatment Solutions

Our products are integrated into the core of wastewater treatment systems and are built for efficiency and reliability, backed by our commitment to excellence and best customer service. With 4 filtration technologies under one roof (screen, disc, microfiber and media) and a broad range of automatic, semi-automatic and manual filters, we are able to effectively treat and filter wastewater according to each facility’s requirements. Our solutions help to improve the efficiency of wastewater treatment and lower operating costs by reducing solid loads, chemical usage and downtime.

You can read more about how our industrial wastewater treatment solutions were implemented in some relevant case studies:

Pre-filtration to Granular Activated Carbon (GAC) Filters, USA

Purification plant water filtration, deep well water to injection water, China

Coal ash pond polishing filter system, coal fired power plant, North Carolina, USA

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