Unit 1 

  • Regulatory water quality standards
  • Selection criteria
  • Surface water treatment Scheme
  • Ground water treatment Scheme 

Regulatory water Quality standards : 

Regulatory water quality standards are standards established by government agencies that set limits on certain pollutants in surface and groundwater. These standards are designed to protect public health and the environment, and are established under laws such as the Clean Water Act in the United States. Standards may be set for various pollutants, including bacteria, heavy metals, pesticides, and other chemicals. Compliance with these standards is typically enforced through monitoring and reporting requirements, and penalties may be imposed for non-compliance. 

In India, water quality standards are regulated by the Central Pollution Control Board (CPCB) under the Water (Prevention and Control of Pollution) Act, 1974. The CPCB sets standards for various parameters such as pH, dissolved oxygen, biochemical oxygen demand (BOD), total suspended solids (TSS), and heavy metals, among others. These standards vary depending on the type of water body and its intended use, such as drinking water, irrigation, or industrial use.

For Drinking water, the CPCB has set standards for physical, chemical, and biological parameters, including pH (6.5-8.5), total dissolved solids (TDS) (500-2000 mg/L), and coliform bacteria (not more than 1/100 ml).

For Surface water, the CPCB has set standards for pH (6.5-8.5), dissolved oxygen (5 mg/L minimum), BOD (3 mg/L maximum), TSS (50 mg/L maximum), and heavy metals such as lead, zinc, and mercury (below the maximum permissible limit).

For Groundwater, the CPCB has set standards for pH (6.5-8.5), TDS (1000-3000 mg/L), and heavy metals such as iron, manganese, and fluoride (below the maximum permissible limit).

These standards are regularly reviewed and updated based on the latest scientific and technological advancements in water quality management. The CPCB also monitors and enforces compliance with these standards through regular inspections and penalties for non-compliance. 

Selection Criteria : 

The selection criteria for water treatment schemes vary depending on the source of the water and the intended use. However, some common factors that are typically considered in the selection process include:

Water Quality: The initial water quality and the desired final water quality are critical factors in determining the appropriate treatment scheme. The more complex the water quality, the more complex the treatment scheme will be.

Water Quantity: The volume of water to be treated will determine the size and capacity of the treatment scheme.

Location: The location of the water source and the intended use of the treated water will influence the type of treatment scheme chosen. For example, a treatment scheme for a remote area may require a different approach than one in a more developed area.

Operational and maintenance requirements: The ease of operation and maintenance of the treatment scheme will be considered when selecting a treatment scheme.

Cost: The cost of the treatment scheme, including capital costs, operating costs, and maintenance costs, will be a major consideration.

Environmental impact: The environmental impact of the treatment scheme will be considered, such as the amount of energy used, the potential for pollution, and the potential for creating waste.

Durability: The longevity of the treatment scheme is also an important factor, as it will need to be maintained over time.

Ease of scalability: The ability to expand or modify the treatment scheme in the future is important if the water demand changes.

Technology: the technology used in the treatment scheme will also be a consideration, as it will need to be reliable and efficient.

Health and safety: The health and safety of the people working on the treatment scheme will also be considered, as well as the safety of the community that will be consuming the treated water.

Surface Water Treatment Scheme : 

A surface water treatment scheme is a system used to treat water from surface sources such as lakes, rivers, and reservoirs. The treatment process typically includes a combination of physical, chemical, and biological processes to remove impurities and make the water safe for human consumption or other uses. 

The basic steps of a surface water treatment scheme include:

Coagulation And Flocculation: This step involves adding chemicals such as alum or iron salts to the water to form small particles called flocs. These flocs help to settle out impurities and make them easier to remove.

Sedimentation: The flocs settle out of the water in this step, and the water is passed through a sedimentation tank to allow the impurities to settle to the bottom.

Filtration: The water is then passed through filters such as sand filters or gravel filters to remove any remaining impurities.

Disinfection: The water is then disinfected to kill any remaining bacteria or viruses. This is typically done with chlorine or ultraviolet light.

pH adjustment: The pH of the water is adjusted to make it safe for human consumption.

Final treatment: The final step in the treatment process is adding any other chemicals or minerals to the water to make it safe and suitable for the intended use.

The type of surface water treatment scheme will depend on the quality of water and the intended use. For example, a treatment scheme for drinking water will typically be more complex and include more steps than a treatment scheme for irrigation water.

It's important to note that some surface water sources may also require advanced treatment such as membrane filtration or reverse osmosis, in order to remove dissolved contaminants such as nitrates, arsenic, and fluoride. 

Ground water treatment Scheme : 

Groundwater treatment schemes are used to treat water from underground sources, such as wells and aquifers. The treatment process typically includes a combination of physical, chemical, and biological processes to remove impurities and make the water safe for human consumption or other uses.

The basic steps of a groundwater treatment scheme include: 

Screening: The water is passed through a screen to remove debris such as sand, gravel, and large particles.

Aeration: The water is aerated to add oxygen and remove gases such as hydrogen sulfide and methane.

Softening: The water is passed through a softening system to remove hardness-causing minerals such as calcium and magnesium.

Filtration: The water is then passed through filters such as sand filters or gravel filters to remove any remaining impurities.

Disinfection: The water is then disinfected to kill any remaining bacteria or viruses. This is typically done with chlorine or ultraviolet light.

pH adjustment: The pH of the water is adjusted to make it safe for human consumption.

Final treatment: The final step in the treatment process is adding any other chemicals or minerals to the water to make it safe and suitable for the intended use.

It's important to note that some groundwater sources may also require advanced treatment such as membrane filtration or reverse osmosis, in order to remove dissolved contaminants such as nitrates, arsenic, and fluoride. Additionally, a groundwater treatment scheme will also include a step of testing for various parameters to ensure that the water is safe for drinking or other uses.

It's also important to monitor the water levels, to ensure that the well does not dry out, and to check for any contamination that may occur in the future.