Rural Water - Quarter 3, 2017 - 40
Excessive sanitizer waste destruction
confirms that nitrification has returned to
previous performance levels.
Assure that effluent pH and chlorine
residual levels are within permit
standards. Adjust feed dosages as
necessary. Monitor pH and chlorine
residuals closely for 24 hours.
If the MLSS pH is < 6.9, boost the
MLSS alkalinity and pH in aeration tanks
with sodium hydroxide (caustic soda),
hydrated lime, soda ash, or magnesium
hydroxide. Each product has its handling,
safety and resulting impact advantages
Check the MLSS biomass. Is it dead or
just inhibited? Are there living protozoa
and metazoa (swimmers, stalks, rotifers,
nematodes)? Is the floc large, irregularly
shaped and somewhat dense or is it
small and dispersed? Cloudy effluents
may result from high amounts of
If nitrification is required, begin strong
recovery steps. Nitrifiers are very
sensitive to shocks and their loss is
often one of the first signs of toxicity.
Unless the biomass has been completely
decimated, nitrification should begin
coming back within about 12-24 hours. To
a. Maintain an influent alkalinity above
200 mg/L as CaCO3. Maintain
process effluent alkalinity above 75
mg/L and preferably over 100 mg/L.
b. Keep return sludge rates high to keep
bacteria exposed to oxygen.
c. Stop wasting for at least 24 hours and
allow the biomass to rebuild itself.
THIRD QUARTER 2017
Excessive landfill leachate loading damage
Filtered and chlorinated secondary effluent reflecting
damage from excessive motor home and septage receipts
Don't waste the nitrifiers you are
trying to grow!
d. Consider adding a carbon and
nutrient mixture of substrates such
as glycerin, carbohydrates or animal
feeds to assist growth with simple-todigest BOD.
6. Seed the biomass with some healthy
waste activated sludge. While re-seeding
may not be absolutely required, it is a
a. If the facility has a sludge holding
tank or digester, consider this sludge
first. Feed the digester contents a
source of carbon BOD to stimulate
microorganism growth and respiration.
Allow at least four hours of mixing
with good DO before sludge transfer.
b. Increase the aeration basin biomass
MLSS by 500 mg/L. This will require
the addition of approximately 425
dry pounds of digester sludge
per 100,000 gallons of aeration
c. If possible, transfer sludge from a
digester to the headworks through
an on-site lift station. Once about
10,000 gallons of digester sludge
has been added, begin to increase
wasting from the clarifier at a flow
rate approximating the digester
transfer rate. Continue to "trade"
or replace damaged sludge with
digester sludge until you confirm that
ammonia rates begin to drop in the
7. If you are suspect of the quality of the
digester sludge, request WAS seed
sludge from a well-operated, nonbulking nearby nitrifying WWTP.
Once operations have stabilized, critique
the episode and plan for the future:
a. Meet with staff and discuss the
events. Review the process control
data leading up to and through
the event's timeline. Discuss and
document any lessons learned.
b. Commit to a better understanding
of your influent nature and
characteristics. Perform routine
testing of a few key influent
parameters such as pH, ammonia,
COD and TSS on a regular basis.
c. Identify future possible toxic waste
sources. Review inside the fence
operations policies first. Discuss
tank cleanings, chemical control,
dewatering ops, vactor wastes and
septage. Then, consider learning
more about external sources as
funeral homes, attendant-living
facilities, oil recyclers and all
commercial dischargers. ●
About the author: Michael Cherniak has
40 years of experience as an environmental
consultant. Besides providing management
oversight for several Florida utility systems,
he has evaluated more than 100 municipal
and industrial water and wastewater
systems. Mike has delivered several
thousand hours of water, wastewater and
hazardous material training to personnel
across the nation. He is a senior vice
president with Woodard & Curran and
resides in Tampa, Florida.