FREQUENTLY ASKED QUESTIONS     Index

FAQ’s on Wastewater Treatment

A.  FAQ’s on Wastewater Treatment – General

  What is water pollution?
  What are the major water pollutants?
  Where does water pollution come from?
  How do we detect water pollution?
  What is eutrophication? How it can be prevented?
  Where does wastewater come from?
  Why is it necessary to treat wastewater?
  What is a wastewater treatment system?
  What is aerobic wastewater treatment?

B.  FAQ’s on Membrane Bioreactor (MBR)

  What is MBR?
  What are the advantages of MBR system over conventional system?
  What are the different types of submerged/ immersed MBR?
  What is INDION IPC MBR?
  What MLSS generally maintained in INDION IPC MBR system?
  What are advantages of INDION IPC MBR?
  What are the features of INDION IPC MBR?
  What is the MLSS and MLVSS?
  What is F/M ratio?
  What C:N:P means and what should be the ratio maintained?

C.  FAQ’s on Fluidized Media Reactor (FMR)

  What is FMR?
  What is the difference between FMR and MBBR?
  What are the types of FMR media?
  What are advantages of FMR system?

D.  FAQ’s on Upflow Anaerobic Sludge Blanket Reactor (UASB)

  What is anaerobic wastewater treatment?
  What are types of anaerobic technologies?
  What is use of Three Phase separator in INDION UASB?
  What are the advantages of INDION UASB compared to conventional UASB?

E.  FAQ’s on Sequencing Batch Reactor (SBR)

  What is INDION SBR?
  What are the steps involved in INDION SBR system?
  What are the advantages of INDION SBR system?
  Can SBR have more than one tank design?
  What is the MLSS and MLVSS?
  What is F/M ratio?
  What C:N:P means and what should be the ratio maintained?

F.  FAQ’s on New Generation Packaged Sewage Treatment Plant (NGPSTP)

  What is NGPSTP?
  Does NGPSTP handle Total Nitrogen?
  Does NGPSTP require air blower?
  Does NGPSTP have lower operating cost compare to other STP technologies?
  What are the features of NGPSTP?
  What are the advantages of NGPSTP?

G.  FAQ’s on Disc Tube Reverse Osmosis (DTRO)

  What is INDION DTRO?
  What is difference between Conventional RO and INDION DTRO?
  What are the limiting conditions for Feed BOD & COD in INDION DTRO?
  What are the types of cycles?
  What are the basic important parameters for monitoring INDION DTRO?
  What are the advantages of INDION DTRO over conventional RO system?

H.  FAQ’s on All Membrane Brine Concentrator (AMBC)

  What is AMBC?
  What are the advantages of AMBC system?
  Is it possible to concentrate high salinity effluent upto TDS concentration of 140000 ppm by membrane based system?
  Does AMBC require thermal energy?
  Does AMBC systems require energy lesser than thermal brine concentrator?
  What pretreatment required for AMBC?
  What operating pressure required in AMBC system?

FREQUENTLY ASKED QUESTIONS ON WASTEWATER TREATMENT

  What is water pollution? Go to Top
  The term water pollution, in general can be defined as any alteration in physical, chemical or biological properties of water by discharge of any sewage or industrial waste or of any liquid, gaseous or solid substances into water as may, or is likely to create nuisance or render such water harmful or injurious to public health of safety, or to domestic, commercial, industrial agricultural or other legitimate uses, or animal life and health.
  What are the major water pollutants?
  The large number of water pollutants may be broadly classified under the following categories:
  1. Inorganic pollutants
  2. Organic pollutants
  3. Thermal pollutants
  4. Radioactive pollutants
  5. Sediments
  6. Infectious agents
  7. Plant nutrients
  Inorganic pollutants
  Inorganic chemical pollutants are naturally found in the environment but due to human development these pollutants are often concentrated and released into the environment. The primary inorganic pollutants of concern are cadmium, copper, lead, zinc, nitrogen, nitrate, nitrite, ammonia, phosphorous, and phosphate.
  Sources:
  Industrial effluent is the major source of Inorganic pollutants cause. E.g. sulfur dioxide from power plants, Ammonia from food processing waste and chemical waster from industrial byproducts. Agricultural fertilizers and surface runoffs are other sources of Inorganic pollutants.
  Harmful effects: Go to Top
 
  • Can kill the fish and other aquatic animals
  • Interfere with suitability of water for drinking and industrial use
  • Toxic pollutants tend concentrate in food chains
  • Degrade the soil microbial activity
  • Loss of vigilance ability
  • Loss of hand to eye coordination
  • NO2 gas can cause coughing, breathlessness, irritation of upper airways, bronco spasms, nauseas and vomiting
  Organic pollutants
  Organic pollutants are basically compounds which may be degraded by micro organisms. It usually uses up the available oxygen in the process of degradation. The optimum DO in natural water is 4 – 6 ppm and hence organic pollutants like sewage waste, oils etc. must be removed to keep water free from such pollutants.
  Thermal pollutants
  Heated water is discharged as industrial effluents. In order to maintain the ecological balance temperature needs to be equalized with the receiving water body. This is an important criterion as increased temperature lowers dissolved DO in water.
  Radioactive pollutants
  Uranium and thorium wastes from mining, refining and its various industrial applications contribute to radioactive wastes. Nuclear power plants, medical and scientific research use are areas where such wastes may be created.
  Sediments
  Erosion removes soil and minerals from crop lands, forests, residential and corporate communities and carries it as sediment. Sediments represent the most extensive pollutants of surface water.
  Bottom sediments are important source of inorganic and organic matter in streams, fresh water, estuaries and oceans. Sediments are also repositories for trace metals such as Co, Cr, Cu, Mn, Mo, Ni, etc.
  Infectious agents
  Wastewater discharged from municipalities; sanatoria, tanning etc. may contain decease producing micro-organisms.
  Plant nutrients
  Growth stimulating plant nutrients include like nitrogen and phosphorous add to the BOD of the water. Presence of nutrients encourages algal growth, which decreases DO levels, and creates problems in treatments.
  Where does water pollution come from?
  The sources of water pollution are categorized as direct and indirect contaminant sources. Direct sources directly discharge contaminants into surface water which includes waste water from factories and sewage from housing colonies.
  Indirect sources include contaminants that enter the water supply from soil/ groundwater systems and from the atmosphere via rain water. Soil and ground waters contain residue of agricultural practices (fertilizers, pesticides, etc.) and improperly disposed of industrial wastes. Atmospheric contaminants are also derived from human practices (such as gaseous emissions from automobiles, factories and even bakeries).
  How do we detect water pollution? Go to Top
  Water is polluted by different contaminants and it can be detected by analyzing water samples in laboratory. Titration test is to detect hardness, dissolve oxygen, carbon dioxide and alkalinity. Colorimetric tests are performed to check pH, Phosphate, Silica, Ammonia and Sulfides. Heavy metal limit test is to determine the level of heavy metals.
  What is eutrophication? How it can be prevented?
  Increase in the concentration of phosphorus, nitrogen, and other plant nutrients in an aquatic ecosystem such as a lake is called eutrophication. This rise is nutrient level results in an accelerated life cycle of water plants like algae, water hyacinth, etc. Vegetative cover restricts entry of light and oxygen in the water. Moreover the degrading debris uses up all available dissolved oxygen in water rendering the water lifeless. Wastewater should be treated for removal of phosphorus and nitrates by various physiochemical and biological methods. Effective technologies are available in removal of nutrients along with BOD and COD. Conventional methods of separate nitrification and denitrification can also be adopted but with increased cost and area.
  Where does wastewater come from?
  Waste water comes from sewage which includes black water (human waste) and grey water (kitchen and laundry waste), septic tank discharge, industrial waste which includes effluent and process water. Agricultural practices also produce waste water by contaminating water with pesticides and fertilizers.
  Why is it necessary to treat wastewater? Go to Top
  Proper treatment of wastewater reduces health risks to humans, animals and prevents surface and groundwater contamination. Wastewater treatment helps to reuse the waste water and reduces the consumption of fresh water.
  What is a wastewater treatment system?
  Wastewater treatment is the process of removing contaminants from wastewater and household sewage, both runoffs (effluents), domestic, commercial and institutional. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. Its objective is to produce an environmentally safe fluid waste stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse (usually as farm fertilizer).
  Treatment system depends on the characteristics of wastewater and treated water quality to be achieved. The treatment plant includes primary treatment such as Screens, Grit Chambers & Clarifiers.

Primary Treatment
Oil Removal Ceramic Membrane System For Oil Removal
Oil And Grease Removal
Clarification Lamella Clarifier
High Rate Solids Contact Clarifier
Color Removal Decolorization Of Effluent Using Electrocoagulation
Decolorization By Indion Color Removal Chemicals In Clarifier
Metal Removal Sulfex Process
Hydroxide Process

Secondary treatment such as biological treatment systems

Go to Top


Secondary Treatment
Aerobic Biological Treatment System Activated Sludge Process/ Extended Aeration Process
Fluidised Media Reactor (FMR)
Membrane Bioreactor (MBR)
Sequencing Batch Reactor
MNR (Metabolic Network Reactor)
Rotating Biological Contactor
Nutrient Removal
Biotower
Anaerobic Biological Treatment System Upflow Anaerobic Sludge Blanket Reactor
Biofilter
Continous Stir Tank Reactor
Waste To Energy - Organic Solid Waste

and Tertiary treatment systems such as

Tertiary Treatment
Filtration Automatic Valveless Gravity Filter
Pressure Sand Filter
Multi Grade Filter
Activated Carbon Filter
Continuous Sand Filter
Recycle System Advanced Oxidation
Recycle System

Chlorination – Chlogen , Indchlor , Ultrafiltration , Reverse Osmosis etc.

  What is aerobic wastewater treatment? Go to Top
  Aerobic wastewater treatment is the process where bacteria requires oxygen for their respiration while oxidizing or consuming organic matter present in the wastewater. Aerobic bacteria can only convert organic compounds when plenty of oxygen is present, because they need it to perform any kind of chemical conversion. Usually the products they convert the contaminants to are carbon dioxide and water.

FREQUENTLY ASKED QUESTIONS ON MEMBRANE BIOREACTOR (MBR)

  What is MBR?
  The membrane bioreactor (MBR) is a combination of the activated sludge process and the membrane technology to provide an advanced level of organic and suspended solids removal.
  What are the advantages of MBR system over conventional system? Go to Top
 
  • Compact System
  • High effluent quality
  • High volumetric load possible
  • High rate of degradation
  • Possible to convert from existing conventional active sludge purification
  • Removes bacteria up to 6 log
  What are the different types of submerged/ immersed MBR?
 
  • Flat Sheet
  • Hollow fiber
  What is INDION IPC MBR?
  INDION IPC MBR membranes are flat “Integrated permeate channel membrane” (IPC membrane) which comprises two membrane layers coated directly on opposite surfaces of a tridimensional textile (3D textile) that is used as support of the membrane layers. The 3D fabric consists of two parallel fabric layers which are spaced apart by loops of monofilament threads, thereby forming a permeate channel between the membrane layers.
  What MLSS generally maintained in INDION IPC MBR system? Go to Top
  INDION IPC MBR system has high MLSS compared conventional ASP and FMR system.
  INDION IPC MBR system has MLSS 8000 – 12000 mg/lit.
  What are advantages of INDION IPC MBR?
 
  • Compact and modular Sewage Treatment Plant with in-built biological system and Ultra filtration system provide consistent treated water quality through membranes which will be free from bacteria & can be directly reused for gardening, car washing, cooling tower, building construction and all secondary purposes.
  • Even in case of floating sludge a solid-free outlet quality can be guaranteed.
  • Operates at Higher MLSS (8000 – 12000 mg/lit) concentration in Aeration tank & higher sludge retention time hence low sludge generation results in reduction in cost for sludge handling system. Sludge generated is completely digested sludge.
  • More efficient at High flux operation compared to other MBR technologies. Requires lower membrane surface area and plant footprint.
  • Substantial reduction in energy consumption due to lower membrane area.
  • State-of-Art Low Fouling and fully back washable membrane helps to reduce cleaning chemical consumption and ensures long membrane life.
  • Lower capital and operation cost of the plant.
  • Footprint can be reduced with available double & triple decker membrane arrangement.
  • STP requires simple civil construction. Plant can be made functional or Upgraded in very short duration by installing prefabricated membrane modules.
  • Fully Automated plant with user friendly Operation and minimal maintenance.
  • Disinfection or more extensive tertiary treatment can be omitted. No need of additional tertiary treatment like Chlorination, Sand filters, Activated Carbon filter or any filtration systems.
  What are the features of INDION IPC MBR?
 
  • Integrated Permeate Channel membranes (IPC) the first fully back-washable flat sheet membrane.
  • Double flux yield compared to other MBR (40 LMH for sewage & 20 LMH for effluent).
  • Lower footprint and energy demand.
  What is the MLSS and MLVSS? Go to Top
  MLSS is Mixed Liquor Suspended Solids & MLVSS is Mixed Liquor Volatile Suspended Solids.
  MLSS is total suspended solids in the aeration tank whereas MLVSS is part of MLSS which actually concentration of biological matter present in aeration tank.
  What is F/M ratio?
  It is ration food to mass ratio i.e. BOD to the microorganism present in the aeration tank.
  What C:N:P means and what should be the ratio maintained? Go to Top
  C – Carbon source which is food for biomass – Either COD or BOD. Normally BOD is considered for the design purpose of aerobic treatment and COD concentration considered for anaerobic treatment.
  N – Nitrogen (TKN) which is Nutrients.
  P – Phosphorus.
  Normally it is in the ratio of C:N:P i.e. 100:5:1 if BOD as Carbon source and 500:5:1 if COD as carbon source for calculation.

FREQUENTLY ASKED QUESTIONS ON FLUIDIZED MEDIA REACTOR (FMR)

  What is FMR? Go to Top
  The Fluidized Media Reactor (FMR) system consists of an activated sludge aeration system where the bacteria is attached on carrier media. These carriers have an internal large surface for optimal contact water, air and bacteria.
  What is the difference between FMR and MBBR?
  MBBR and FMR are same technology with different name.
  What are the types of FMR media?
 
  1. PP Media
    1. High protected surface area
    2. High physical & chemical resistance of media
    3. Low annual losses (3 – 5%)
  2. Carbon Impregnated Media
    1. Porous, adsorbing PU media impregnated with activated carbon
    2. High adsorbent capacity
    3. High internal porosity with extremely large surface area
  What are advantages of FMR system? Go to Top
 
  • Reduced power and operating costs
  • No continuous sludge recycle
  • Significant reduction in space due to high surface area and loading of media
  • Less maintenance
  • Easy up gradation and extension of existing wastewater treatment plants

FREQUENTLY ASKED QUESTIONS ON UPFLOW ANAEROBIC SLUDGE BLANKET REACTOR (UASB)

  What is anaerobic wastewater treatment? Go to Top
  Anaerobic treatment is a biological process carried out in the absence of O2 for the stabilization of organic materials. The stabilization of organic material by conversion to methane, carbon dioxide, new biomass and inorganic products. Anaerobic treatment is most suitable for wastewaters with COD concentrations in the high strength range (> 2000 mg/l).
  What are types of anaerobic technologies?
 
  1. Fixed Film reactor
  2. Fluidised Bed reactor
  3. Up flow Anaerobic Sludge Bed (INDION UASB)
  What is use of Three Phase separator in INDION UASB?
  Three Phase separator enables the reactor to separate gas, water and sludge mixtures.
  What are the advantages of INDION UASB compared to conventional UASB? Go to Top
 
  • Feed distribution boxes ensure even distribution of effluent at bottom of UASB.
  • Less power consumption by gravity feeding system.
  • Higher Life of internals – FRP fabricated from Iso-Phthalic Resin & all the pipes are in HDPE.
  • Gas Dome – INDION UASB gas dome is of FRP Iso-Phthalic Resin which is inert to this environment.
  • Less replacement of internals with life of internals more than 12 – 15 years.
  • Inlet & outlet launders are open and hence can be inspected, cleaned & maintained easily.
  • Even inlet distribution system, uniform outlet collection system and provision for scum removal which increases the efficiency of UASB and consistent performance over long period of operation.
  • Higher gas generation.
  • Outside Lamella clarifier, which gives better control on the settling of solids.

FREQUENTLY ASKED QUESTIONS ON SEQUENCING BATCH REACTOR (SBR)

  What is INDION SBR? Go to Top
  INDION SBR is modification of conventional activated sludge process. In INDION SBR, equalization, biological treatment and clarification of treated wastewater carried out in single tank with time control sequence.
  What are the steps involved in INDION SBR system?
 
  1. Fill: The inlet valve opens and the tank is being filled in, while mixing is provided by means of blower (air).
  2. React (aeration): Aeration of the mixed liquor is performed during the second stage by the use of mechanical aerators or transferring air into fine bubble diffusers fixed to the floor of the tank (diffused aeration system).
  3. Settle (sedimentation/ Clarification): No aeration or mixing is provided in the third stage and the settling of suspended solids starts.
  4. Draw (decant): During the fourth stage the outlet valve opens and the “clean” supernatant liquor exits the tank.
  What are the advantages of INDION SBR system?
 
  • Flow rate fluctuations do not upset the plant as flow rate variation is limited to equalization tank only. In SBR, there is only level control of fixed volume.
  • Operating flexibility and control – Better process control (MLSS, BOD loading and F/M ratio) as in batch process one can monitor and adjust the parameter very easily when compared with continuous process.
  • Consistent good quality treated sewage for reuse application (BOD – < 10, TSS – < 20).
  • Nitrification & Denitrification, Primary clarification, biological treatment and secondary clarification can be achieved in a single reactor vessel.
  • Elimination of clarifiers, sludge recirculation system.
  Can SBR have more than one tank design? Go to Top
  Yes, we can design SBR system with multiple SBR basin as per influent flow rate.
  What is the MLSS and MLVSS?
  MLSS is Mixed Liquor Suspended Solids & MLVSS is Mixed Liquor Volatile Suspended Solids.
  MLSS is total suspended solids in the aeration tank whereas MLVSS is part of MLSS which actually concentration of biological matter present in aeration tank.
  What is F/M ratio?
  It is ration food to mass ratio i.e. BOD to the microorganism present in the aeration tank.
  What C:N:P means and what should be the ratio maintained? Go to Top
  C – Carbon source which is food for biomass – Either COD or BOD. Normally BOD is considered for the design purpose of aerobic treatment and COD concentration considered for anaerobic treatment.
  N – Nitrogen (TKN) which is Nutrients.
  P – Phosphorus.
  Normally it is in the ratio of C:N:P i.e. 100:5:1 if BOD as Carbon source and 500:5:1 if COD as carbon source for calculation.

FREQUENTLY ASKED QUESTIONS ON NEW GENERATION PACKAGED SEWAGE TREATMENT PLANT (NGPSTP)

  What is NGPSTP?
  NGPSTP is New Generation Packaged Sewage Treatment Plant which combines aeration and clarification in single unit.
  Does NGPSTP handle Total Nitrogen? Go to Top
  Yes. NGPSTP has anoxic zone which can convert nitrates to nitrogen gas by denitrification process.
  Does NGPSTP require air blower?
  No. NGPSTP works on principle of rotating biological contactors.
  Does NGPSTP have lower operating cost compare to other STP technologies? Go to Top
  Yes. Air blower and pumps are not required in NGPSTP due to which it has lower OPEX compare to other aerobic technologies.
  What are the features of NGPSTP?
 
  • All in one single packaged STP
  • Modular design
  • High quality effluent
  • 3 month sludge storage capacity
  • Minimal maintenance
  • GRP constriction – no corrosion
  What are the advantages of NGPSTP? Go to Top
 
  • Minimal land requirement
  • Lower OPEX (operating cost)
  • Lower CAPEX (Capital cost)

FREQUENTLY ASKED QUESTIONS ON DISC TUBE REVERSE OSMOSIS (DTRO)

  What is INDION DTRO? Go to Top
  Disc tube reverse osmosis (INDION DTRO) technology has a distinct module structure than the spiral reverse osmosis technology. The feed flow enters the pressure vessel and reaches the disc in a short distance. With open flow channels, the feed flows 180 degrees over one side of the membrane and reverse flow to the other side, flowing on to the next disc. The reject and permeate flow down to the outlet. This flow reversal causes turbulence and an open channel flow path reduces the need for extensive pre-treatment.
  What is difference between Conventional RO and INDION DTRO?
  The Conventional RO system requires extensive pre treatment to meet stringent feed limiting condition like SDI < 3, turbidity < 1 NTU, O&G – NIL. Hence UF system is must as pre-treatment to meet above SDI limits. Membrane replacement cost is comparatively higher as entire membrane needs to be replaced.
  Whereas, DTRO requires less pre-treatment due to its unique assembly feature and can handle SDI up to 15 to 20, turbidity < 10, O&G upto 10 ppm. Hence only Sand Filtration is sufficient as Pre-treatment to DTRO system. It can handle higher fluctuations in feed quality. Membrane replacement cost is lower as individual membrane cushion can be replaced.
  What are the limiting conditions for Feed BOD & COD in INDION DTRO?
  There are no such feed limiting conditions for COD & BOD in INDION DTRO.
  What are the types of cycles?
 
  1. Service Cycle – It is service cycle for filtration process
  2. Rinsing/ Flushing Cycle – Flushing cycle with permeate water
  3. Cleaning in place (CIP) Cycle – Chemical cleaning in process cycle
  4. MGF backwash
  What are the basic important parameters for monitoring INDION DTRO?
  Basic important parameters for monitoring are Conductivity, TSS, COD, pH, ORP, Total Hardness, Silica and Temperature.
  What are the advantages of INDION DTRO over conventional RO system? Go to Top
 
Aspects of Comparison Spiral RO Disc – Tube RO
Pre-treatment Extensive pre-treatment required Less pre-treatment required
Silt Density Index SDI < 5 SDI 15 to 20
Turbidity < 1 NTU < 10 NTU
Oil & Grease Nil 10 ppm
Minimal Pre-Treatment For Suspended Solids UF MGF
Chemical Treatment As per requirement As per requirement
Feed Quality Fluctuation Unable to cope up with excess feed fluctuations Can handle fluctuations in feed quality
Recovery Depends on type of feed effluent and type of membrane Depends on type of feed effluent and type of membrane
BOD & COD < 30 ppm No limiting conditions
Membrane Replacement cost Entire membrane element need to be replaced Individual membrane cushions can be replaced
Average Membrane Life 3 years 3 years

FREQUENTLY ASKED QUESTIONS ON ALL MEMBRANE BRINE CONCENTRATOR (AMBC)

  What is AMBC? Go to Top
  The AMBC stands for All Membrane Brine Concentrator, it is advanced technology achieved brine concentration via osmotically assisted reverse osmosis based on combination of forward osmosis and reverse osmosis.
  What are the advantages of AMBC system?
 
  • Operates on high salinity waters that are beyond the reach of a conventional reverse osmosis process.
  • Low power consumption compared to other competing processes.
  • Simple operation and high reliability.
  • It utilises electrical power, eliminating the use of thermal energy and the complexities common to other brine concentration approaches; could be incorporated into existing seawater RO facilities with zero or little impact on the existing operations.
  • It reduces the size of expensive, high maintenance and complex thermal brine concentrators and crystallisers in zero liquid discharge (ZLD) applications by significantly reducing the feed fluid volume.
  Is it possible to concentrate high salinity effluent upto TDS concentration of 140000 ppm by membrane based system?
  Yes. We can concentrate high TDS effluent upto 140000 ppm with help of AMBC system.
  Does AMBC require thermal energy? Go to Top
  The AMBC process uses only electrical energy and does not require any thermal energy or vapour compression.
  Does AMBC systems require energy lesser than thermal brine concentrator?
  Yes. AMBC based system requires fraction of energy compared to thermal energy brine concentrator.
  What pretreatment required for AMBC?
  The pre-treatment requirements for AMBC are similar to that of a RO system. Impurities that can scale or foul the membranes are needed to be minimized prior to AMBC.
  What operating pressure required in AMBC system? Go to Top
  The operating pressures required in AMBC system are very much similar to that of seawater desalination RO systems i.e. 60 – 70 bar.



Revised on: 15 Feb. 2022 Uploaded on: 16 Feb. 2022
Revision: 1