Research

• Settleability of activated sludge (AS) was increased by activated carbon (AC) particles.

• Washout of AS inoculum was effectively minimized during start-up in granular SBRs.

• Nitrogen and phosphorus removals were in SBRs using acetate or acetate-propionate. 

• AC particles decreased start-up periods for achieving efficient total nitrogen removal.

• P removal was 2-fold higher via EBPR pathway in SBRs augmented with AC particles.

*Published in J. Environ. Manage.

• GAC addition promoted formation of biofilms and aerobic granular sludge (AGS).

• Segregation of PAOs in biofilms and AGS in GAC augmented SBR

• Higher abundance of PAOs in large (>0.5 mm) biomass size fraction

• Preferential enrichment of PAOs observed in biofilms than in the co-existing AGS.

• PAOs enrichment led to rapid establishment of EBPR in the presence of GAC particles.

*Published in Sci. Total Environ.

• Granular activated carbon (GAC) enhanced aerobic granulation using propionate.

• Effective TN and TP removals was achieved by propionate-fed aerobic granules.

• Phosphorus was removed by enhanced biological phosphate removal.

• GAC shifted microbial community and increased abundance of Thauera sp.

• Abundance of PAOs was higher in GAC-biofilms than co-existing granules.

*Published in Bioresour. Technol. Rep.

• Removal of 4000 mg l−1 NH4+-N was achieved using AGS process.

• Functional and structural stability of AGS was maintained at low COD/N ratios.

• Bacterial diversity decreased at higher influent ammonium concentrations.

• Nitrite oxidizing bacteria washed out at higher NH4+-N and lower COD/N ratios.

• Nitritation-anammox was the major nitrogen removal pathway.

*Published in Bioresour. Technol.

• GAC addition decreased start-up period for aerobic granulation and nutrient removal

• Higher biomass retention and granular fraction was achieved in the presence of GAC

• Effective ammonia and phosphorus removals from sewage in GAC bioreactors

• Phosphorus removal was enhanced in GAC-augmented granular sequencing batch reactor

• Higher abundance of polyphosphate accumulating organisms in GAC bioreactors

*Published in Curr. Sci. 

• GAC enhanced aerobic granulation in pilot-scale bioreactors treating real sewage.

• Efficient biological nitrogen and phosphorus removals in tropical climate (T ≈ 30 °C)

• Nitrogen removed via nitritation-denitritation due to nitrite oxidizing bacteria.

• GAC enriched polyphosphate accumulating organisms for enhanced bio-P removal.

• First report on pilot-scale granular SBR and GAC addition for sewage treatment

*Published in Sci. Total Environ.

• De novo granulation of sewage-borne microorganisms for aerobic granular sludge (AGS) formation and nutrient removal.

• Novel activated sludge inoculum-independent method for AGS cultivation and sewage treatment.

• Granular activated carbon (GAC) enhanced de novo granulation of sewage-borne microbes.

• GAC addition biological nitrogen removal via nitritation-denitritation pathway.

• Higher enrichment of PAOs and EBPR in GAC-augmented AGS SBR.

*Published in Environ. Res.

• The sludge was dominated by smaller granules at 15-20°C as compared to 30°C.

• Granular stability was not impacted by short-term changes in temperature from 15 to 30°C.

• N and P removals were impacted by sudden decrease in T from 30° to 15°C.

• Effective N and P removals were maintained by decreasing T from 30° to 15°C in 5°C steps.

• N and P were removed by partial nitrification and EBPR pathways at T ranging from 15 to 30℃.

*Published in J. Environ. Chem. Eng.

• Sewage treatment by CAS, activated sludge SBR and aerobic granular sludge (AGS) SBR were compared.

• Biopolymer extraction reduced biosolids content of AGS by 54%

• Biopolymer of activated sludge from SBR formed hydrogel beads but not from CAS.

• Biopolymer of AGS was bestowed with superior gel-forming ability due to high GG blocks.

• Biopolymer extraction form AGS improves resource recovery and sustainability of WWTPs.

*Published in Sep. Purif. Technol.

• Aerobic granular sludge (AGS) was formed within 50 days during sewage treatment

• AGS outperformed with 99% phosphorus removal as against 57% by activated sludge

• High abundance of PAOs and enhanced bio-P removal in tropical climate (T=30°C)

• AGS showed resilience to oxytetracyline (OTC) and maintained high nutrient removals

• Nitrogen and phosphorus removals have dropped to 78% and 16%, respectively, with flocs

*Published in J. Environ. Chem. Eng.

• Lactate dependent simultaneous SeIV and SeVI removal by aerobic granules and activated sludge.

• Higher rate of SeIV and SeVI reduction by aerobic granular sludge than activated sludge.

• Simultaneous and efficient reduction of SeIV and SeVI by aerobic granular sludge.

• SeVI reduction rate was enhanced by pre-exposure of biomass to SeIV.

• Ammonium removal via nitriation-denitriation pathway at different Se-loadings.

*Published in J. Hazard. Mater. Lett.

• First report on sustained selenite reduction by aerobic granular sludge.

• Simultaneous COD, nitrogen and selenite removal by aerobic granular sludge.

• Efficient selenite bioreduction and better entrapment of Se (0) in AGS.

• Selenite reduction by AGS was associated with lower colloidal Se (0) in liquid.

• Ammonium was mainly removed through nitrogen removal via the nitrite pathway.

*Published in Water Res.

• Selenite reduction and Bio-Se0 retention were dependent on size of aerobic granules.

• Large sized aerobic granules showed efficient selenite reduction and Bio-Se0 entrapment.

• Microbacterium azadirachtae isolated from granules exhibited efficient selenite reduction.

• M. azadirachtae cells immobilized in alginate beads exhibited selenite reduction and Bio-Se0 entrapment.

*Published in J. Environ. Manage.

• Ammonium was mainly removed through nitrogen removal via the nitrite pathway.

• Efficient bioreduction of SeIV and TeIV oxyanions by aerobic granular sludge (AGS). 

• First report on bioreduction of tellurite using AGS sequencing batch reactor. 

• Biogenic Se and Te were majorly associated with the AGS. 

• Ammonium removal via nitritation-denitritation was not impacted by toxic metalloids.  

• Bio-P removal was higher at 73% in the AGS bioreactor fed with SeIV and TeIV.

*Published in J. Hazard. Mater.

• Complete, sustained and lactate-dependent conversion of up to 175 mg/L TeIV to Te0

• Biogenic Te0 nanostructures were associated with aerobic granular sludge

• Partial inhibition of ammonium removal and lower abundance of AOB by TeIV

• Efficient nitrogen removal via nitritation-denitritation at different initial TeIV loadings

• Higher P-removal in TeIV-fed reactor due to hydroxyapatite precipitation

*Published in J. Environ. Chem. Eng.

• Aerobic granules had compact and stable microbial structure at low DO ≤ 2 mg L−1.

• Simultaneous removal of COD, ammonium and azo dye by aerobic granular sludge.

• Ammonium was removed mainly through ammonium removal via nitrite pathway.

• Azo dye biodecolourization by aerobic granules under microaerophilic conditions.

• Azo dye decolourizing and nitrifying (Nitrospirae) bacteria were detected.

*Published in J. Hazard. Mater.

• Aerobic granules cultivated by feeding acetate plus 2,4-dinitrotoluene for the first time.

• 2,4-dinitrotoluene was rapidly removed when fed along with acetate or lactate.

• 2-amino-4-nitrotoluene was formed in minor amounts during 2,4-DNT removal.

• Aerobic granules removed 2,4-DNT by both oxidative and reductive pathways.

• Nutrient removal by aerobic granules was not impacted by 10 mg L−1 2,4-DNT.

*Published in Int. Biodeter. Biodegr.

• • Aerobic granular sludge exhibited 35% higher oxytetracycline removal than activated sludge.

  • Oxytetracycline (OTC) removal was sustained by biotransformation and required carbon source.

  • AOB and PAOs abundance was decreased upon exposure to oxytetracycline

  • Nitrogen and phosphorus removals were >99% and 70%, respectively, in OTC fed SBR.

  • Micrococcus luteus grew as aggregates and exhibited OTC biotransformation potential.

*Published in Chemosphere

• Granulation of seawater microbes for saline wastewater treatment

• Development of granular sludge directly from microbes present in the seawater

• Simultaneous C, N & P removal under saline conditions

• Effective biological nitrogen and phosphorus removal by saline granular sludge

• Granules had lower species richness than seawater bacterial community

• Published in RSC Environ. Sci-Wat Res. 

• hAGS was cultivated from autochthonous seawater-born microbes.

• Biological N and P removals were unaffected at 3.4 to 12% salt concentrations.

• Efficient NH4+-N removal via nitritation-denitritation pathway at 3.4 to 12% salt.

• Effective bio-P removal via EBPR pathway at 3.4 to 12% salt concentrations.

• Stappia was the dominant genus in halophilic aerobic granular sludge at 12% salt.

*Published in Bioresour. Technol.

• First report of cultivation under saline conditions

• Use of autochthonous biofilm enabled rapid cultivation of halophilic AGS

• Effective total nitrogen and phosphorus removal by hAGS

• P was removed via enhanced biological phosphorus removal mechanism.

• Nutrient removal was rapidly established using autochthonous microbes.

*Published in Bioresour. Technol. Rep.