The Central Pollution Control Board estimates that sewage generation will increase to over 120,000 MLD in India by 2051. Moreover, only one-third of the sewage is treated before its release in rivers, lakes, and ponds. These daunting numbers suggest the urgency for wastewater management. However, many challenges like land availability, infrastructure, and capital issues decline the progress of wastewater treatment plants.
Given various water and wastewater treatment challenges, several technologies have been developed. On the contrary to the conventional wastewater treatment methods, modern technologies are cost-effective, energy-saving, efficient, and leave less footprint.
Modern wastewater treatment technologies
- Rotating biological contactor (RBC)
A rotating biological contactor is a type of fixed film media filter and is highly beneficial for reducing organic matter and ammonia from the water. In a packaged treatment plant, it is more efficient to remove ammonia.
Working:
-
-
- It contains a series of rotating discs on a rotating shaft.
- The discs are covered with biological slime (anaerobic and aerobic microorganisms).
- They are partially submerged in water so that when they rotate, they can absorb oxygen from the air and break down BOD and organic matter in wastewater.
- As the discs are partially submerged, they eliminate the requirement pumps for additional aeration.
- Moreover, they are slimed, so there is no need to recycle the sludge.
-
Benefits:
-
-
- Short contact period because of sizeable active surface
- Capable of handling varied flow
- Easily handled and low operation costs
- Low energy consumption
- Less sludge production
-
- Advanced sequencing batch reactor (ASBR)
An advanced sequencing batch reactor is an industrial processing tank for wastewater treatment. It is used for municipal as well as industrial wastewater treatment.
Working:
-
-
- It has a series of tanks that operate on the ‘fill and draw’ principle.
- Tanks are filled and operated as a batch reactor.
- The mixed water is then allowed to settle.
- The clear supernatant is drawn from the tank.
- The phase between the draw and fill is termed as idle, also used effectively for sludge wasting.
- The cycle can be divided into; fill-react-settle-draw-idle.
-
Benefits:
-
-
- Less expensive than other biological treatments
- Require less space
- Produces high-quality effluent
- Simple design
- Low energy consumption
-
- Integrated fixed-film activated sludge (IFAS)
It is a wastewater treatment process that combines suspended and sessile biomass and is widely used for retrofits. In addition, it provides additional biomass to meet stringent effluent discharge limits in the treatment facility.
Working:
-
-
- It is equivalent to the conventional activated sludge process, but IFAS systems allow additional bacterial populations on a fixed surface.
- Here, dispersed media is present in the aeration basin, and fixed media is fixed in the tank, eliminating the need to increase suspended growth.
- The two distinct biological populations act cooperatively with Mixed Liquid Suspended Solids (MLSS) and degrade most organic matter.
- Moreover, they also effectively reduced nitrogen load from wastewater.
-
Benefits:
-
-
- Increases sludge retention time
- The system’s nitrification is restored faster
- Improves process stability
- Reduce sludge production
- Highly efficient biodegradation
-
Emerging technologies for wastewater treatment
- Biological filtration and oxygenated reactor (BIOFOR):
-
- Enhances primary treatment with the addition of coagulation and flocculation
- Effective two-stage filtration with biologically active media and enhanced external aeration
- Deep reactors reduce land requirement
- A compact and robust system
- Submerged aeration fixed film (SAFF):
-
- A fixed film media with enhanced oxygen supply through submerged aeration
- Plastic media offers a high void ratio and specific area
- Large biomass and long solid retention time in the reactor
- Rim flow sludge suction clarifiers:
-
- Clarifiers have inlets along the rims
- On the contrary to conventional scrappers, sludge is sucked out through suction boxed arms
- Lesser footprints and denser sludge
- Eco-bio-blocks:
-
- Exfoliated bricks of volcanic ash that do not degrade by themselves and allows microorganisms into their crevices
- These microorganisms further facilitate aerobic or anaerobic degradation based on the oxygen conditions
- It is often used for polishing the water before its release into natural waterbodies
Modern and advanced technologies are expected to drive India towards improved and efficient wastewater treatment. Moreover, the Internet of Things also plays a crucial role as IoT sensors are used to collect real-time data of treatment processes and are one of the effective ways to improve water treatment plants’ efficiency. Similarly, big data tools can calibrate and validate the data for the users and help the managers streamline the process.