Complete Guide to Wastewater Treatment: Causes,Pros & Cons, and Plant Types
Wastewater treatment plays a crucial role in today's modern world. Not only is it important for environmental protection, but also for public health and the economy. Untreated wastewater can contaminate water resources, thereby causing water pollution. Inadequately treated water can cause many waterborne diseases. Water pollution can have drastic environmental impacts, and is also a threat to aquatic ecosystems. Those times when clean water was found in almost every water body is quite far away. In this blog, we will discuss causes of wastewater, types of sewage, the common pollutants in wastewater, wastewater treatment process, advantages and disadvantages of wastewater treatment, and different types of wastewater treatment plants and components.
How Water Becomes Wastewater
Causes & Consequences
Before more, it is important to know how and why. What urged the need for water treatment and the rise of wastewater treatment plants? What raised the demand for advanced waste management, efficient sewage treatment plants, sustainable practices, air pollution control devices, etc? Why is environmental health a concern in the modern world? The following are the causes of the increased generation of wastewater, which led to the rise of wastewater treatment technologies.
- Increased Wastewater Generation
- Water Scarcity
- Urbanization
- Industrialization
- Increased Energy Consumption
- Environmental Concerns
- Technological Advancements
- Regulatory Compliance
More people means more water usage. As the population increases, the amount of wastewater generated, as well as the need for clean water, also increases. This population growth can not only put a strain on existing water resources but also lead to environmental concerns, like water pollution, soil contamination, and air pollution.
Apart from that, a wide range of activities from manufacturing, mining, oil refining, and textile industries also generate wastewater. Industrial wastewater and agricultural runoff from farms and livestock also contribute to this.
Also, as more people are moving to cities and choosing to live there, there is a growing demand for wastewater treatment infrastructure. These factors urged many industries, including the beverage industries, to invest in advanced and efficient water treatment plants. Concerns about industrial activities, the rise of waterborne diseases, and stricter regulations from public authorities also paved the way for water treatment.
Types of Sewage
- Domestic sewage is the wastewater generated from residential properties, commonly referred to as sanitary sewage.
- Industrial sewage originates from manufacturing processes or chemical operations.
- Storm sewage, also known as stormwater, is the runoff collected from precipitation, which is directed through a system of pipes or open channels.
Common Pollutants in Wastewater
Numerous pollutants can be seen in wastewater generated from different sources, including homes, industries, and agricultural activities, contains numerous pollutants such as:
Physical Pollutants
The most commonly found physical pollutants are suspended solids, sediments, and grit. These contaminants not only pose threats to aquatic ecosystems but can also clog waterways and damage wastewater treatment facilities. Apart from that, wastewater often harbours nutrients such as nitrogen and phosphorus. This triggers excessive algae growth, leading to eutrophication and a decline in water quality.
Chemical Pollutants
Chemical pollutants in wastewater are also equally concerning. They can severely impact both the environment and human health. Dangerous chemicals, and heavy metals, such as lead, mercury, and arsenic, can pile up in the food chain.
Additionally, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and other synthetic organic substances frequently make their way into wastewater. These chemicals can infiltrate soil, groundwater, and surface water, posing serious risks to public health and the ecosystem.
Biological Pollutants
Biological pollutants, such as bacteria, viruses, and parasites are also present in wastewater. These pathogens can lead to waterborne diseases, including cholera, typhoid, and dysentery.
Wastewater Treatment Process
Pre-Treatment
Pre-treatment is the first step in the wastewater treatment process. Wastewater from households, industries, and institutions flows into the treatment plant through a network of sewers. Pre-treatment involves removing large objects and debris that could damage equipment or disrupt the treatment process.
Physical screens or grinders are used to remove large objects such as sticks, rags, and other debris. Grit and sand are also removed through gravity settling or centrifugation. This step helps to prevent damage to equipment and ensures that the treatment process runs smoothly.
Primary Treatment
Primary treatment is the next step in the wastewater treatment process. The goal of primary treatment is to remove suspended solids and organic matter from the wastewater. This is done through sedimentation, where wastewater is held in tanks and suspended solids settle to the bottom.
Flotation is also used in primary treatment, where air is bubbled through the wastewater to remove suspended solids. The solids that settle to the bottom of the tank are called sludge, and the liquid that remains is called effluent. Primary treatment typically removes 30-50% of the suspended solids and organic matter from the wastewater.
Secondary Treatment
Secondary treatment is the next step in the wastewater treatment process. The goal of secondary treatment is to remove organic matter and nutrients from the wastewater. This is done through biological treatment, where microorganisms break down organic matter and nutrients. This is also used in secondary treatment, where chemicals are added to remove nutrients and other contaminants. The most common method of secondary treatment is the activated sludge process, where microorganisms are added to the wastewater to break down organic matter. Secondary treatment typically removes 80-90% of the organic matter and nutrients from the wastewater.
Tertiary Treatment
Tertiary treatment is an additional step in the wastewater treatment process that involves further removal of contaminants and pollutants. The goal of tertiary treatment is to produce a high-quality effluent that can be safely discharged into the environment.
Tertiary treatment may include physical or chemical processes such as filtration, disinfection, and nutrient removal. Filtration removes remaining suspended solids, while disinfection kills bacteria and other microorganisms. Tertiary treatment can also involve advanced technologies such as membrane bioreactors and advanced oxidation processes.
Sludge Treatment
Sludge is the solid material that is removed from the wastewater during treatment. Sludge treatment involves thickening, stabilization, and disposal. The thickening reduces the volume of sludge, while stabilization reduces its odour and pathogen content.
Sludge can be disposed of through landfilling, incineration, or land application. Landfilling involves burying the sludge in a landfill, while incineration involves burning the sludge to produce energy. The land application involves using the sludge as fertilizer or soil amendment.
Effluent Disposal
The final step in the wastewater treatment process is effluent disposal. The treated wastewater, or effluent, is discharged into the environment. This may involve discharge to surface waters, reuse for non-potable purposes, or groundwater recharge. This is to safely dispose of the effluent while protecting public health and the environment.
Wastewater Treatment Plants
Industrial Wastewater Treatment Plants & Components
Effluent Treatment Plant (ETP)
ETP treats effluent (wastewater) generated from various industries such as textiles, pharmaceuticals, and chemicals. ETPs use physical, chemical, and biological processes to remove pollutants and contaminants from the effluent.
The different processes involved are equalization, pH control, coagulation, sedimentation, filtration, disinfection, sludge drying, etc.
Sewage Treatment Plant (STP)
This wastewater treatment plant treats domestic sewage and wastewater generated from residential areas. STPs use physical, chemical, and biological processes to remove pollutants and contaminants from the sewage.
Odour Control System
An odour control system specifically treats odorous compounds present in wastewater. These systems use chemical or biological processes to remove or neutralize odorous compounds.
Different types of technologies used for this include chemical scrubbers, biological filters, ozonation, chemical oxidation, thermal oxidation, vapour phase carbon absorption, odour neutralizers, etc.
Anaerobic Reactor (UASBR)
UASBR uses anaerobic microorganisms to break down organic matter present in wastewater. UASBRs are commonly used to treat high-strength wastewater generated from industries such as food processing and brewing.
Dissolved Air Flotation (DAF)
These types of wastewater treatment plants use dissolved air to remove suspended solids and other contaminants from wastewater. DAFs are commonly used to treat wastewater generated from industries such as paper pulp, and food processing.
Moving Bed Biofilm Reactor (MBBR)
MBBR uses a moving bed of media to support the growth of biofilm. MBBRs are commonly used to treat wastewater generated from industries such as textiles and pharmaceuticals.
Continuous Fill Batch Reactor
A continuous fill batch reactor uses a continuous fill and batch treatment process to remove pollutants and contaminants from wastewater.
Membrane Bio Reactor (MBR)
A membrane bio reactor is a crucial component of an industrial wastewater treatment plant that uses a combination of biological and physical processes to remove pollutants and contaminants from wastewater. MBRs use membranes to separate the treated water from the biomass. It is ideal to treat a wide range of organic substances and microbiological contaminants.
Sequential Batch Reactor (SBR)
Pollutants and contaminants from wastewater are removed using a sequential batch treatment process. SBRs are commonly used to treat wastewater generated from industries such as food processing and brewing.
Advantages and Disadvantages of Wastewater Treatment
When it comes to the advantages and disadvantages of wastewater treatment, many factors are considered.
Water treatment includes several advantages across residential, commercial, and industrial settings. This includes the removal of pathogens, pollutants, and contaminants. Water treatment plays a vital role in making water safe for drinking, industrial use, and recreational activities.
Effective water treatment also helps to prevent waterborne diseases, reduces the risk of many health problems, and protects aquatic ecosystems.
However, water treatment also has some disadvantages. This includes high operational and maintenance costs, energy consumption, and the generation of residual waste products, such as sludge and brine. Regular routine maintenance, annual maintenance, and repairs costs will be necessary.
Some water treatment processes can also remove beneficial minerals and nutrients from the water, and if not properly managed, can have negative environmental impacts.
But advanced wastewater treatment plants can minimize even these disadvantages and ensure a better outcome. Day by day, technology is evolving and innovative methods are being adopted. An efficient and advanced system can minimize the cons and offer a better output.
Conclusion
Effective wastewater treatment plays a huge role in maintaining the balance between human activities and the environment. Wastewater treatment plants serve as a critical barrier against water pollution, protecting not only human health but also the health of ecosystems. By investing in wastewater treatment infrastructure and adopting sustainable management practices, communities can ensure a safe and environmentally responsible water supply.
As a trusted water treatment plant manufacturer, Alantech offers efficient and high-performing water treatment solutions. With years of expertise, dedicated specialist teams, and a robust network of partners, we ensure high-performance and reliable wastewater treatment facilities. Being a top wastewater treatment plant provider, we also offer a diverse range of products, including custom bottling machines, conveying systems, and global pressure tanks.
