For waste water

Types of wastewater treatment plant machines

Wastewater treatment equipment is used to treat sewage or industrial effluents to remove impurities and make it eco-friendly for disposal or reuse. Advanced waste water treatment plant machines use a combination of physical, chemical, and biological processes to achieve the desired quality of water。

• Bar screen/Grating: This is the first step to remove larger solid impurities such as rags, plastic, and sticks from the water. Manually or mechanically operated screens/gratings are used to hold the solids. The held solids are called screenings, and they are discarded in a landfill.
• Grit chamber: The flow of water is kept in a velocity where heavier inorganic solids like sand, gravel, and egg shells are settled while organic matter remains afloat. This is done to avoid abrasion to pumps and other equipment down the line. The settled heavier matter is called grit and is disposed of separately.
• Primary/Settling tank: In this tank, the organic matter is allowed to settle. Nearly 60% of the solids settle down in this tank. The settled matter is called primary sludge, and the matter that remains is referred to as primary effluent.
• Digestion tank: Here, anaerobic bacteria break down organic matter in the primary sludge. The breakdown of organic matter releases methane gas. This gas may be collected and used to run the plant or sold off to make the process further economical.
• Secondary treatment: In this tank, aerobic bacteria degrade the organic matter. The Secondary treatment may use activated sludge or biofilm such as trickling filters or moving beds. Nearly 90% of the organic matter is degraded in this secondary treatment. Sometimes chemical treatment such as chlorination or ozonation is used to further improve the quality of water.
• Polishing pond: The polishing pond is an optional step. Here algae digest remaining organic matter in presence of sunlight. The algae are allowed to settle before disposal. The process of purification is called algal bloom.
• Secondary clarifier: In this clarifier, the remaining bacterial sludge is separated from the treated water. Over 90% of the sludge is recirculated to the primary tank to maintain bacterial culture, while the remaining 10% is disposed of in a landfill.
• Disinfection: Here the treated water is disinfected using chlorination, UV or ozone to remove pathogenic micro-organisms from the water.
• Reverse osmosis plant: If the treated water is to be reused, a reverse osmosis plant is required to remove chemical impurities such as heavy metals. Here a semi-permeable membrane is used to filter the water under high pressure.

Finally, the treated water is released to a river, lake or sea, or stored in a reservoir. The solid waste or sludge is further treated in a dewatering press or composting facility before it is disposed of in a landfill.

The waste water treatment equipment can be classified as municipal or industrial depending upon the source of waste water. There are sewage treatment plants and effluent treatment plants to handle municipal and industrial waste water respectively. Within these types of treatment facilities, specific equipment may employ physical, chemical, or biological processes to treat and purify the water.

Specification and maintenance for waste water

Specification

Some critical specification details of waste water that is typically used around the world are as follows:

• Industry experts usually say that a waste water treatment plant should be able to treat an average flow that is equal to 1.5 times its design flow per day.
• A general breakdown of the capacity of a waste water treatment plant per population served is as follows:
  • 10,000 - 1.0 MGD
  • 50,000 - 5.0 MGD
  • 100,000 - 10.0 MGD
  • 500,000 - 30.0 MGD
  • 1,000,000 - 50.0 MGD
• The Design population of the treatment plant is calculated by multiplying the estimated number of people living in a particular area by a waste water generation factor of 75% of the water used by each individual.
• The typical life of a waste water treatment plant is estimated to be anywhere between 20 to 30 years.
• The capacity of an aeration system in a waste water treatment plant is estimated by the required mass transfer of oxygen read in pounds per day.

More sophisticated waste water treatment systems are now taking into consideration the energy recovery from waste water by using various methods such as anaerobic digestion, membrane bioreactors and others. These systems are more complex and their specifications will vary greatly. In addition, some waste water treatment facilities are contributing to the circular economy by using treated waste water for irrigation or other low-grade industrial uses. These systems will have very different specifications and capacity. So, it is best to check the specifications of such complex systems separately.

Maintenance

It is necessary to maintain waste water treatment systems regularly to ensure that they are operating optimally and are in good working condition. By doing so it will help extend the life of any treatment system and will reduce the risk of environmental hazards that occur if such systems malfunction. Here are some crucial waste water treatment system maintenance tips:

• Refer to manufacturer manual- Always check the system maintenance schedule as detailed in the treatment plant manufacturer’s manual. Follow the schedule carefully and ensure that any necessary repairs are carried out as per instructions provided by the system manufacturer.
• Regular inspections- Develop a routine inspection schedule to closely monitor crucial parts of the treatment system such as aerators, pumps, filters, disinfectant and control panels. Regular monitoring will help in the timely identification of any wear, leaks, clogs, damages or operational issues that are not visible at first glance.
• Calibrate and test controls- Regularly test and calibrate treatment system controls to ensure the precise functioning of the system. Also, check the various alarms and settings for proper functioning to prevent any untoward hazards or environmental concerns.
• Maintenance of ancillary equipment- Ensure that any ancillaries of a waste water treatment system such as pumps, compressors and conveyors are also receiving the proper maintenance they require on a regular basis so that the entire system can function without a hitch.

Usage scenarios of water pumps

A sewage water pump performs exceptionally well at a sewage treatment plant. This facility exists to rid water of contaminants before returning it to the environment. The pump thrusts wastewater through treatment units such as screens and aerators. It helps to keep the plant running smoothly by preventing clogging, maintaining efficient airflow, and enabling the breakdown of solids.

Pits and trenches frequently get deluged with surface water runoff during heavy rains, but a sewage water pump can save the situation. The pump comes in handy for draining stormwater from these places to stop flooding, structural damage, and safety hazards. It swiftly removes the water to create space for normal operations to continue.

Landfills and construction sites are also excellent places to use a sewage water pump. In these places, the pump helps remove leachate and groundwater from below the surface. It stops the buildup of pressure that can cause land sinks or destabilize structures. Using a sewage water pump for this purpose helps to protect the integrity of the land and construction site.

Separating solid waste from liquid provides an efficient method of recycling, and a sewage water pump aids this process in filtration systems. It pumps effluents through filters to extract valuable materials such as dust and faecal solids for further processing or disposal. Without the water pump, many recyclable solids would end up in the wastewater stream.

Choosing the right wastewater treatment plant

Before investing in a wastewater treatment plant, it's essential to understand the factors influencing the decision to select an STP or another form of wastewater treatment facility.

• Source and amount of sewage:

  The type of sewage treatment facility will depend on the kind of sewage and the amount produced daily. For example, a compact STP with an MBBR design may suit a small residential community, while an open land STP in a distant part of the city may treat more sewage daily and in a more cost-effective manner.

• Local laws and regulations:

  Local laws will determine how much water can be recycled and what happens to the treated sewage. If the local norm is to discharge in a river, an advanced STP with tertiary treatment may be essential. On the other hand, if all water goes to the ground, a facility with an adequate deep percolation system will be sufficient.

• Land availability:

  In some areas like urban centers, land is a premium commodity, and underground STPs with digester, MBR, and recycling facilities may help save land and provide more water. Open land STPs may be used in other areas where land is inexpensive and available.

• Cost:

  The initial and recurring costs of a sewage treatment facility also play an essential part in decision-making. If the local laws permit only non-cache facilities, then the cost of treatment will have to be incurred.

• Environmental impact:

  Many communities are environmentally conscious and may prefer STPs that consume less energy and produce less carbon. Such facilities may help mitigate climate change and global environmental impacts.

• Technical support

In some areas, abundant trained staff can handle the intricacies of advanced STPs, while in others, a simple facility will be better because of a lack of trained manpower. It is essential to assess the need for technical support and STP maintenance staff.

FAQ

Q1: What is the domestic waste water treatment process?

A1: The domestic waste water treatment process typically comprises four steps: preliminary treatment (filtering out larger solids), primary treatment (settling tanks to separate sludge and effluent), secondary treatment (biological processes to degrade organic matter), and tertiary treatment (advanced treatments like filtration and disinfection).

Q2: What are some recent advancements in waste water treatment technology?

A2: Recent advancements include smart waste water treatment plants (integrating IoT for real-time monitoring), energy recovery systems (for biogas production), decentralised treatment solutions (for small-scale, on-site processing), and nutrient recovery technologies (to recover phosphorous and nitrogen).

Q3: What are the key challenges in waste water treatment?

A3: The key challenges include managing the energy consumption of treatment plants, ensuring compliance with evolving regulatory standards, addressing the variability and complexity of waste water composition, securing adequate funding for infrastructure maintenance and upgrades, and promoting public awareness of waste water as a valuable resource.