Bleaching powder dosing for disinfection in waste water treatment plant
Sources of Informations given below
Manual http://cpheeo.gov.in/upload/uploadfiles/files/Chapter%206-9.pdf
1. https://www.epa.ie/pubs/advice/drinkingwater/Disinfection2_web.pdf
2.http://jeb.co.in/journal_issues/200710_oct07/paper_04.pdf
The pilot scale disinfection units located at two
different UASBR based STPs have been selected for this study.
One of these pilot plants has been constructed after 27 MLD UASBR
based STP, Noida (Uttar Pradesh, India) and is based on
chlorination using calcium hypochlorite (either slurry form or liquid
high test hypochlorite, HTH) with a capacity of 2 million liter per day
(MLD). The other 1 MLD DHS-biotower pilot plant, developed by
Prof. H. Harada (Machdar et al., 1997), is based on fixed film
aerobic process and has been constructed after 40 MLD UASBR
based STP, Karnal (Haryana, India). These STPs, based on
UASBR technology, consists of preliminary treatment (Screen and
Grit Chamber), UASBR and final polishing pond (Fig. 1).
A schematic diagram of the pilot plants at Noida and Karnal
is presented in Fig. 2 and 3 respectively. The chlorination unit of 2
MLD consists of a sump, mixing unit and baffled contact chamber
(3m x 7m) and a specific dose of chlorine was mixed with a separate
pipe. The 1 MLD DHS-biotower based on fixed film aerobic process
consists of a sump and reactor having plastic rectangular sheets
onto which triangular prism polyurethane foams were tiled. Raw
sewage after UASBR treatment was supplied to the chlorination unit
and DHS-biotower
In case of chlorination unit, initially the bleaching powder
was used as a disinfectant from day 1 to day 48 and later on it was
found that there was no residual chlorine in the bleaching powder,
so the bleaching powder was replaced with calcium hypochlorite as
disinfectant after 48th day. The dose of disinfectant was 5 mgl-1 from
day 1 to day 16 and was increased to 20 mgl-1 from day 20. The
contact time for the reaction between wastewater and disinfectant
was 30 min throughout the study.
Results and Discussion
Reduction of fecal coliform: To achieve good disinfection, the
contact time and dose are extremely important. A longer contact time
is required for complete disinfection to occur. As per Lindsay (2004),
a contact time of 30 minutes is a minimum, and if the dose remains
constant, the contact time may necessitated to be increased at low
temperatures or higher pH to obtain the same level of disinfection.
Typical chlorine doses for municipal wastewater disinfection are
about 5-20 mgl-1 with a contact time of 30 to 60 min (Lazarova et al.,
1999). During this study, 5 and 20 mgl-1 of disinfectant doses for a
fixed contact time of 30 min was applied. It was observed that a dose
of 20 mgl-1 was very effective for the reduction in indicator
microorganism (fecal coliforms). Initially when a dose of 5 mgl-1 was
used, the reduction in fecal coliforms count was less than 90%. It
may be attributed to the fact that the minimum dose required for the
killing of microorganism was not sufficient as there was high chlorine
demand due to the presence of high concentration of organic matter
and suspended solids in the UASBR effluent. The average fecal
coliforms count was reduced from 3.58 x 105
(± 1.02 x 105
) MPN/
100ml to nil at a dose of 20 mgl-1 and 30 min contact time (Fig. 4a).
Thus the results shows that almost 100% removal of fecal coliforms
has been observed after chlorination; however at certain days i.e.,
from day 7 to day 14 and from day 44 to day 53 (Fig. 4a), the
number of fecal coliforms present in the wastewater effluent after
disinfection was increased. It could be explained on the basis of
type of chemical used for the chlorination. During this period,
bleaching powder was used. Later on it was found that the chemical
used at the plant does not have any residual chlorine. Chlorination
was switched to the fortified brand of the calcium hypochlorite, high
test hypochlorite (HTH). It indicated that chlorination was very effective
in the removal of fecal coliforms if the regular operation and
maintenance (O and M) is ensured.
COPY RIGHTS : TO AVOID COPYRIGHT VIOLATIONS, ALL POSTS ARE SHOWN ALONG WITH SOURCES FROM WHERE ITS TAKEN. PLEASE CONTACT ME IN MY EMAIL SALEEMASRAF@GMAIL.COM , IF YOU ARE THE AUTHOR AND YOUR NAME IS NOT DISPLAYED IN THE ARTICLE.THE UNINTENTIONAL LAPSE ON MY PART WILL BE IMMEDIATELY CORRECTED.
I HAVE SHARED ALL MY PRACTICAL WATER TREATMENT EXPERIENCES WITH SOLVED EXAMPLE HERE SO THAT ANYBODY CAN USE IT.
SEARCH THIS BLOG BELOW FOR ENVO ,COMPACT STP,ETP,STP,FMR,MBBR,SAFF,IRON,ARSENIC,FLUORIDE,FILTER,RO,UASB,BIO GAS,AERATION TANK,SETTLING TANK,DOSING,AMC.
SEARCH THIS BLOG
Showing posts with label bleaching powder. Show all posts
Showing posts with label bleaching powder. Show all posts
Thursday, December 05, 2019
Bleaching powder dosing for disinfection in waste water treatment plant
Labels:
bleaching powder,
disinfection,
dosing,
etp,
STP,
wtp
New Delhi, India
New Delhi, Delhi, India
Environmental Entrepreneur,Green Biz.NRN Murthy of Infosys says that we Indians are weak in execution.We need to realize the need and practice of gud project management. Form a group of competent Managers,Give them responsibilities and review the project from day One.
Subscribe to:
Posts (Atom)