Prospects for a self-sustainable sewage treatment system: A case study on full-scale UASB system in India's Yamuna River Basin
UASBs on Yamuna River basin
Yamuna River serves as local water supply in India, but is heavily polluted
Indian government is constructing sewage treatment plants to combat river pollution
Since UASBs are low-cost, the government of India launched project to construct 16 full-scale UASBs in Yamuna River Basin
Total capacity: 598,000 m^3/d
Design of STPs with UASBs in the Yamuna river basin
The concentration of pollutants in effluent from these UASBs usually does not meet effluent standards of most developing countries
UASBs also do not remove pathogenic bacteria, nitrogen, and phosphorus, so post-treatment is necessary →
Effluent from UASB reactors on the Yamuna River basin goes to polishing ponds called Final Polishing Units for post-treatment
FPUs are simple and cheap
Study: authors sampled water quality from 15 of the UASB STPs located in 10 Indian towns
The STPs were nearly identical in design and construction
HRT in UASB: 8.4-10.7 h
HRT in FPU: 1.0-1.6 days
Combined systems designed to handle 150-200 mg/L of BOD, 275-400 mg/L of SS
Capacities of STPs ranged from 10,000 m^3/day to 78,000 m^3/day
Incoming sewage characterized as high- and medium-strength domestic wastewater
Study findings
Organic removal
None of the STPs met standard of 30 mg/L for BOD
Typical range of 120 to 400 mg/L in STPS
Probably b/c raw sewage strength larger than what was designed for
SS concentrations higher than standard of 50 mg/L
SS concentrations ranged from 63 mg/L to 622 mg/L
Probably due to accumulation of sludge inside the UASB
-Could be solved by periodically removing excess sludge and scum
Nutrient removal
Very high concentration of ammonia left in the effluent: 19-54 mg/L
Ammonia-nitrogen concentrations higher in FPU effluent than UASB effluent
Fecal coliform removal
Poor effluent quality
-Due to fact that the STPs were constructed without consideration of FC removal
Conclusions/recommendations
None of the investigated STPs produced effluent that complied with discharge standards
To meet those standards, STPs must be properly maintained/operated, sewage sources identified, and facilities upgrades
If that doesn’t work, post-treatment should be reevaluated
Prospects for a self-sustainable sewage treatment system: A case study on full-scale UASB system in India's Yamuna River Basin