5 Industry Challenges and Methods for Meeting Effluent Regulations in India

It is important to know how wastewater treatment can play an important role in your overall safety. It is about complying with effluent regulations whether you own, operate, or manage municipal or industrial wastewater facilities.

According to the Pollution Control Board, failing to recognize this aspect of the wastewater treatment process could result in penalties or prosecution.

The guidelines for your facility will differ depending on the location and the industry of your facility. Also whether the effluent is released into the environment as required by the standards of the Pollution Control Board.

1. The biochemical oxygen demand in your effluent is high.

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen that aerobic biological organisms require to break down organic matter into smaller molecules.

The discharge of BOD from WWTPs is required to be regulated at a concentration of 30 mg/l*.

As these levels rise, they deplete the oxygen needed by other aquatic species, resulting in increased algae growth and damage to the marine environment where wastewater is disposed of.

As a result, many effluent regulations impose restrictions on these amounts, ensuring that local waterways are protected.

Biological oxidation is a common method for controlling BOD levels by ensuring the correct balance of “food” and organic matter. Biological oxidation is the mechanism of lowering the organic content of effluent while rising BOD levels. 

This is possible with the proper method of aeration, in which air is introduced into the effluent to increase the rate of biological oxidation. Thus, increasing the level of settleable solids can be removed by filtration or clarification from the effluent.

We do have a perfect product for this solution, which is the Advanced Fluidised Media Reactor (FMR). It is a combination of aeration, plate-type clarifier, and chlorine contact tank all built in a single prefabricated MS vessel with special paints used for corrosion resistance externally.

We do also have Membrane Bioreactors with options of flat sheet and hollow fiber membranes.

2. Chemical oxygen demand (COD) in your effluent is high

The chemical oxygen demand (COD) in your effluent is high. Chemical oxygen demand (COD) is the amount of oxygen required to chemically oxidize the organic matter in wastewater into carbon dioxide and water. COD is a measure of the number of organic pollutants present in wastewater.

The discharge of COD from wastewater treatment plants (WWTPs) is regulated in order to prevent water pollution. High levels of COD can negatively impact aquatic life, cause oxygen depletion, and lead to the formation of harmful chemicals.

To control COD levels, many WWTPs use advanced treatment processes such as biological oxidation, chemical oxidation, or a combination of both.

Biological oxidation uses bacteria to break down organic matter in wastewater, while chemical oxidation involves adding chemicals to the water to oxidize the organic matter.

Our Solution:

Proper aeration is a key component in controlling COD levels through biological oxidation. In this process, air is introduced into the wastewater to increase the rate of bacteria growth and organic matter breakdown.

This results in a reduction of the organic content in the effluent and thus lowers the COD levels.

Range of solutions for COD removal, including our Advanced Fluidised Media Reactor (FMR) combines aeration, plate-type clarifier, and chlorine contact tank in a single prefabricated MS vessel with special paints used for corrosion resistance externally.

Additionally, Membrane Bioreactors with options of flat sheet and hollow fiber membranes can be used to further treat wastewater and reduce COD levels.

By implementing these solutions, WWTPs can effectively control COD levels and ensure that they meet local regulations to protect the environment and aquatic life.

3. Too many suspended and dissolved solids are present in your effluent.

Your procedures and the degree to which you enforce the effluent regulations are set up by the Pollution Control Board. It can vary depending on the amount of total suspended solids (TSS) and total dissolved solids (TDS) found in your facility’s wastewater.

The dry weight of suspended particles that are not dissolved in water and can be trapped by a filter is known as TSS. TSS, when found in high concentrations in wastewater, can be detrimental to marine organisms. In aquatic environments, TSS can reduce oxygen levels and kill insects. 

The recommended concentration to meet effluent regulations limits for total suspended solids is set at 100 mg/l*.

TDS is the term used to describe the inorganic salts and small amounts of organic matter in water. The principal constituents are usually calcium, magnesium, sodium, and potassium cations and carbonate, hydrogen carbonate, chloride, sulfate, and nitrate anions. 

They can cause harm to water life, irrigation, and crops and can also penetrate into groundwater.

These are some of the treatments that can help reduce TSS and TDS present in your effluent:

Coagulation: 

This method begins with a range of mixing reactors, usually one or two reactors adding various chemicals to remove all fine particles from water by incorporating them into heavier settling particles. 

Aluminum-based coagulates including Alum and polyaluminum chloride are the most commonly used coagulates. A small pH adjustment may also be used to coagulate the particles.

We provide chemical dosing systems that dose these coagulates in water.

Flocculation: 

The next step after the coagulation process is flocculation. In the flocculation chamber, the coagulated particles are slowly stirred together with long-chain polymers, resulting in visible, settleable snowflakes. 

We do provide flocculation tanks provided with slow-speed agitators mounted.

Sedimentation: 

Depending on the quantity and type of suspended solids, we have different types of filtration. One is a very commonly used Lamella Clarifier, which is a plate-type clarifier wherein plates are inclined at an angle. With the rise rate velocities of 1.4-1.8m/hr, we can achieve very good quality filtrate.

Part of the sludge collected at the bottom can then be recirculated back to the flocculation tank and part of the sludge is then disposed of after dewatering.

We also provide a High Rate Solid Contact Clarifier which does the dual purpose of suspended solids removal as well as precipitation of Hardness & Silica salts with dosing of Lime, Soda Ash, and Dolomite.

The filtrate quality is less than 25 ppm and the sludge, which can be a combination of suspended solids as well as precipitated salts, can be dewatered and then disposed of through solid waste management. 

Sand or carbon filtration: 

Multigrade Sand filters are MS or FRP vessels filled with different grades of sand and used to get filtrate quality of <5ppm. The backwash is done for 15-20 min once a day to clean all the suspended solids entrapped in the media.

Similarly, a carbon filter is also an MS/FRP vessel filled with carbon which can be of desired Iodine value to achieve the filtrated water free of color, odor, and free of chlorine.

Reverse Osmosis 

TDS reduction may need a combination of Ultrafiltration followed by 2 or 3 stages of Reverse Osmosis to concentrate the final reject with minimal quantity.

This final reject is then passed through an evaporator in combination with a centrifuge or dryer to achieve solids which would then be disposed of through solid waste management.

4. Higher concentration of nitrates and phosphates in your effluent.

If high concentrations of nitrates and/or phosphates are not removed from wastewater and are dumped into local areas, they can increase BOD and cause significant weed growth, algae, and phytoplankton formation.

This can result in eutrophication, or the deoxygenation of a body of water, which can destroy microbes and eventually contribute to hypoxia or natural dead zones. Human and food waste, detergents, and chemicals are also examples of how they can reach the drainage system.

For these reasons, limits on these chemicals are usually strictly applied. Discharge of nitrogen and/or phosphorus in wastewater is limited to a maximum concentration of 10 mg/l* and 5 mg/l* respectively.

Nitrates can be extracted using a range of treatments, including ion exchange, reverse osmosis, and standard biological therapy and denitrification. 

We provide Anoxic tanks with recirculation prior to aeration for the process of denitrification. 

Wastewater treatment is usually a combination of technologies. We provide the appropriate solution based on the input wastewater quality.

Coagulation/chemical precipitation is an appropriate way to extract phosphates from the wastewater, based on the types of phosphates present. 

Biological treatments such as the use of an Upflow Anaerobic Sludge Blanket Reactor (converts organic matter to methane and carbon dioxide) and an aeration tank (injects oxygen to encourage biological floc formation) can also be useful.

5. Oil and grease contents in your effluent.

In addition to damaging human health and destroying marine species, high levels of oil and grease in wastewater will clog sewage and drainage pipes.

These pollutants, which are often released into wastewaters as byproducts of food processing, are strictly prohibited from being released with effluent. 

Oil and grease discharge is limited to a concentration of 10 mg/l*.

Certain facilities which see large quantities of oil and grease will use dissolved air flotation (DAF) to treat their wastewater.

Dissolved air flotation is a water treatment process that clarifies wastewater by the removal of suspended matter such as oil or solids. The removal is achieved by dissolving air in the water or wastewater under pressure and then releasing the air at atmospheric pressure in a flotation tank basin.

Some types of filtration, such as ultrafiltration and activated charcoal, may also be used to remove traces of oil successfully. 

We also provide Oil and Grease separators which are used for the removal of free-floating oils and grease removal respectively.

6. High amount of Chromium, Copper, Zinc, and other Heavy Metal contents in your effluent.

There has been growing concern about the various effects of heavy metals on humans and marine environments since the second half of the twentieth century.

Due to strict effluent regulations, improved cleaning/purification technologies, and changed industrial practices, metal output emissions have decreased in many countries in recent years.

*Discharge elements such as Cr, Pb, Mn, Cu, Zn, Cr, Hg, As, Fe, and Ni in wastes, which are major industrial sources.

Heavy metal removal from inorganic effluent can be achieved by conventional treatment processes such as chemical precipitation, ion exchange, and electrochemical removal.

We provide the following services:

• We do provide chemical precipitation solutions. These processes have some disadvantages in the production of toxic sludge.
• We do have specialty resins from ION EXCHANGE (I) LTD for the removal of Iron, Manganese, and Arsenic.
• Membrane separation has been increasingly used recently for the treatment of inorganic effluent due to its convenient operation. There are different types of membrane filtration that are provided by us such as ultrafiltration (UF), nanofiltration(NF), and reverse osmosis (RO).
• Solutions of Physico-chemical treatments for removal of heavy metals from industrial wastewater.

Aquamech has over 21 years of experience in water and wastewater treatment systems, so please feel free to contact us if you have any questions. 

We will guide you through the process of determining the best wastewater treatment solution at a reasonable cost for your facility.

*Derived from The GENERAL STANDARDS FOR DISCHARGE OF ENVIRONMENTAL POLLUTANTS at cpcb.nic.in