Report on recent issue regarding adverse quality of STP treated water at MY HOME JEWEL:
1. On 27.01.2023 morning I received a call from MHJ informing me about the smelly water in
the flush. On inquiry with the STP supervisor who informed that as the STP by-pass line was
chocked previous day and due to sudden inflow into the STP collection sump and since the
collection sump has lesser capacity, the operator had no option but to operated the STP at a
much higher capacity by switching-on the larger pump. Which had lead to such a situation.
The MLSS escaped the system.
2. When the pumping is at a much higher rate than usual, the MLSS that in the aeration tank
gets washed away and without the operators realizing it, proper treatment of the effluent
was not done before it was discharged for reuse into the subsequent down stream treated
water tanks.
3. Subsequent to my visit to the STP on the 27.01.2023 to investigate and apprise the MC
members on the STP situation, it was noticed that the MBBR media floating in the Aeration
tank were less than what it normally should have been. I confirm this by taking a sample
portion of the effluent from the aeration tank into the 1000 ML MLSS Jar and I found that
the active media (to be read as floating MBBR media) quantity was far less than what it
should have been. On further inspection it became apparent that the MBBR media was
insufficient in quantity to sustain and support a surge in in-flow.
4. It should be realized that during a surge flow condition, the MLSS which is in suspension and
not attached to the media (due to insufficient media quantity) in the aeration tank, would
simply get washed away which leads to a process upset condition in the STP. The MBBR
media aids in attaching the MLSS to itself and even during a surge flow condition the MLSS
would sustain in the aeration tank.
5. Therefore it is suggested that 30 m3 of media be added in the aeration tank on emergency
basis to over come such a situation in future.
6. Also, we had in the past meetings had asked and emphasized for the STP by-pass line to be
aided with a pump to handle such surge flow situations. There are several emails and
reminders to the effect. It is imperative to have a properly and working by-pass line so that
the in-flow surge can be handled to avoid such adverse STP process condition.
Once the STP reaches an upset condition, it takes a lot of effort and time to bring it back to
normal for processing the effluent satisfactorily.
7. We have now over come this situation with great effort and have since introduced fresh
bacteria culture into the Aeration Tank to boost MLSS back to normal levels at a very fast
rate.
8. In order to save ourselves from a repeat in such a situation we suggest the following:
a.) The Aeration tank hold a capacity of 300 m3 of effluent. We suggest that at least 10% of
the volume which is 30 m3 of media be introduced as an emergency measure so that
sufficient MLSS can be sustained in the aeration tank to improve quality of the treated
water.
b.) The STP by-pass line be installed with a suitable pump so that the excess surge water can
be let out of the system harmlessly.
c.) Every year about 5% media to be added to the aeration tank to sustain as media loss
during the course of the year.
d.) Side steam MBR system be incorporated so that the amount of sludge carry-over can be
reduced also this will boost the quality of the treated water greatly.
e.) The old Ozone machine to be replaced with new ones to further enhance the quality of
the treated water.
9. The Odor control Gas scrubber vessel and media needs urgent replacement as the existing
scrubber vessel is now 7 years old is in a damaged condition and media inside has out lived
its service life and needs to be replaced as well as it cannot be regenerated any further.
We request your immediate action on the above suggestions to over come adverse and
unpleasantness situations in the immediate future with the STP.
Thank you,
for ENGINEERED SOLUTIONS
MELVIN PHILIP
DATE: 04.02.2023