Page 330 - Industrial Wastewater Treatment, Recycling and Reuse

302 Industrial Wastewater Treatment, Recycling, and Reuse

Table 7.8 Sewage treatment technologies employed in STPs of class II towns
Combined Average
No. of capacity size
S. No. Technology plants (MLD) (MLD) Remarks
1. ASP (Preceded 1 12.5 12.5 Less area
by primary requirement
sedimentation) and no
option for
energy
recovery
2. Grit channel or 3 23.83 7.9 Energy
PST+UASB recovery is
+PP an option
3. Waste 21 161.26 7.7 Adopted
stabilization where land
ponds cost is not a
constraint
4. Trickling filter 2 16.68 8.3 Operation and
maintenance
5. Kamal 2 10.13 5.1 Land area for
technology acceptability
(for
plantation)
Total 29 (100%) 224.4
(100%)
Source: Status of Sewage Treatment in India, CPCB, November 2005.

• At present, the field scenario of treatment processes at STPs of Class I
cities involves activated sludge process (ASP) being used to an extent
of 59.5% of total installed capacity, and UASB technology is used to
26% of total installed capacity. These technologies have been the most
commonly used, including primary or tertiary treatment units. Waste
stabilization ponds (WSPs), in series, are implemented in up to 28% of
the plants, even though the treatment efficiency is less than 60%.
• The series of WSP technology is the most commonly employed technol-
ogy, covering 71.9% of total installed capacity and 72.4% of STPs in Class
II towns. The UASB technology covers 10.6% of total installed capacity
and 10.3% of STPs.
• ASP technology is seen as adaptable for large cities because it requires
less space as compared to the other two technologies, namely, UASB
technology and WSP technology. The WSP technology requires a large
area for its implementation. However, the extended-aeration sludge