Review of Upflow Anaerobic Sludge Blanket Reactor Technology: Effect of Different Parameters and Developments for Domestic Wastewater Treatment

Table 2

Comparison of aerobic and anaerobic treatment methods.

Parameter	Aerobic treatment	Anaerobic	References
Process	Degradation of organic matter occurs in the presence of oxygen	Degradation of organic matter occurs in the absence of oxygen	[83]
By-products	The process generates carbon dioxide, water, and excess biomass	The process generates carbon dioxide, methane, and excess biomass	[44, 84]
Applicability	Highest removal efficiency for wastewater having low to medium organic content (COD < 1000 ppm) that is complex to biodegrade, for example, municipal sewage and refinery wastewater	Highest removal efficiency for wastewater having medium to high organic content (COD > 1000 ppm) and easy biodegradability, for example, food and beverage industry’s wastewater rich in organic content. But also applicable to low strength wastewater (COD > 300 and <1000 mg/L)	[25, 85]
Reaction kinetic	Decay rate = 0.06 d^−1	Decay rate = 0.03 d^−1	[44, 83, 84]
Sludge yield coefficient (kgVSS/Kg COD)	0.35–0.45 (relatively high) Biomass yield is fairly constant irrespective of the type of substrate metabolized	0.05–0.15 (relatively low) biomass yield is not constant and varies with the type of substrate metabolized	[86]
Posttreatment	Direct discharge, followed by filtration/disinfection	Generally done by aerobic methods	[21, 83, 87, 88]
Foot print	1.0 to 2.4 kgCO2/kgCOD removed (depending on the wastewater strength)	0.5 to 1.0 KgCO2/kgCOD removed (depending on the wastewater strength)	[44, 45, 85, 89]
Capital cost	12–40 US$/inhab.	40–65 US$/inhab.	[49, 90–92]
Typical technologies	Activated sludge, trickling filters, extended aeration, oxidation ditch, downflow hanging sponge (DHS), Membrane Bioreactor (MBR), Moving Bed Bioreactor (MBBR)	UASB, continuously stirred tank reactor/digester/Upflow Anaerobic Filters, ultrahigh rate fluidized bed reactors, hybrid high rate reactors, two-stage UASB reactor	[15, 24, 60, 67]