The document describes the process that wastewater undergoes at the Ithaca Area Wastewater Treatment Facility (IAWWTF). Heavy metals are primarily removed in primary treatment through settling in tanks, while nutrients are removed in both primary and secondary treatment through aeration tanks and clarifiers. Tertiary treatment further removes some remaining nutrients. The document also discusses different techniques used at other treatment facilities worldwide to remove heavy metals and nutrients from wastewater.

1. Bar screens
and Lift
Pumps
WasteWaterIn(Influent)
Primary
Settling
Tanks
Cyclone
De-Gritter
Settled Solids
Thickener
1
Thickener
2 (Both
thickeners
used for de-
watering)
Primary
Digester
Secondary
Digester
The Belt
Press
(De-waters the sludge
and returns water back
into the system, back
into the primary
settling tanks.)
Landfill De-watered Sludge A Polymer is added to separate sludge
from water.
Aeration
Tanks
Aeration
Tanks
Final
Clarifiers
Final
Clarifiers
Primary Effluent
Waste Sludge
Tertiary Treatment
(Uses Ferric Chloride for
Phosphorous Removal)
Chlorine
Added (For
Disinfection)
Sulfur Dioxide
Used to Remove
Residual
Chlorine
EffluentReleased
intoCayugaLake
Key
Red Arrows: Heavy
Metals
Yellow Arrows: Nutrients
Arrow width: quantity of
heavy metals or nutrients
The Paths of Nutrients and Heavy Metals at IAWWTF
By Shae Varmette
When thinking of a wastewater treatment facility, the
first thing that comes to mind is fecal matter. However,
there is more in what is flushed down the toilet and goes
down the sink than just plain waste. Heavy metals and
nutrients, as well as chemicals from personal care
products, are present in the influent that reaches Ithaca
Area Wastewater Treatment Facility (IAWWTF.) IAWWTF
does not receive a large quantity of heavy metals, but
faces large loads of nutrients daily. Some municipal
wastewater treatment facilities must process greater
amounts of heavy metals on a regular basis, and must
treat different types of waste.
Heavy metals and nutrients follow to a large extent
the same paths through the IAWWTF but are removed in
different quantities at each step. Heavy metals are
removed from the Influent in the greatest quantity in
primary treatment, in the primary settling tanks. The
great majority of the heavy metals settle out with thirty
percent of the organic matter load in the Primary settling
tanks. Once this occurs, almost all heavy metals that are
still present are either removed in secondary treatment in
the aeration tanks and final clarifiers, or the final tertiary
treatment. Nutrients, however, are removed in the
greatest amounts in both the primary and secondary
treatment, leaving only a small amount of residual
nutrient to be removed in the tertiary treatment.
Phosphorous is a nutrient the IAWWTF, and many other
treatment facilities, processes large quantities of on a
daily basis (about 200 pounds a day.) Of this 200 pounds
of phosphorous they process daily, 170-180 pounds are
removed from the Influent in primary and secondary
treatment, with about half of the remaining twenty
pounds of phosphorous being removed by the tertiary
treatment, and about 10 pounds daily being released in
the effluent entering Cayuga Lake.
Because heavy metals and nutrients are things that
every wastewater treatment plant must remove, in
varying amounts, facilities across the world have
developed many different techniques for removing them.
In Hong Kong, they flush their toilets with sea water, and
as such, their influent has a different chemistry. Using
this unique wastewater to their advantage, they
developed the SANI system (Sulfate reduction,
Autotrophic dentrification and Nitrification Integrated) to
remove nutrients. This process uses the sulfate produced
by toilets flushing seawater as an electron carrier for the
sulfur-cycle biotransformation, which removes the
phosphorous and nitrogen quickly, and produces less
sludge than the IAWWTF produces with it’s method.1
Other plants have tried growth biofilm techniques to
remove nutrients as a supplement to other techniques.
The hanging or suspended biofilm reduces the amount of
biomass that drifts to other processing units and
effectively removes nutrients. It is used as an extra step
after secondary treatment in aeration tanks.2 Certain
facilities, although it is expensive, use UV light to kill
pathogens in water after tertiary treatment.4 Plants that
face a high concentration of heavy metals in their influent
have also adopted varied methods for removing and fixing
heavy metals. The solid waste produced post-treatment
in high metal facilities carries most of the heavy metals,
and this gets incinerated, forming fly ash. In China some
plants make the heavy metals in the fly ash less volatile,
so that they cannot evaporate, with a pre-treatment of
phosphate.5 The last, and perhaps most interesting,
method for heavy metal removal I found was using water
Hyacinth. Water Hyacinth is a plant that has a high
growth rate, absorbs a lot of elements, and accumulates
high levels of toxins. In Thailand, this was used by state-
funded research to remove heavy metals from a reservoir,
which collected water from the main sanitation canals
and was located directly next to an industrial factory.3
Although the methods are varied and numerous,
nutrients and heavy metals must be removed at every
water treatment plant, or they could harm the
surrounding environment.
1Di, Wu, Ekama George, Wang Hai-Guang, Wei Li, Lu Hui, Chui Ho-Kwong, Lui
Wen-Tso, Brdjanovic Damir, Van Loosdrecht Mark, and Chen Guang-Hao.
“Simultaneous Nitrogen and Phosphorus Removal in the Sulfur Cycle-
Associated Enhanced Biological Phosphorus Removal (EBPR) Process.” Elsevier
Ltd. (December 3, 2013).
http://www.sciencedirect.com/science/article/pii/S0043135413009652.
2Dinh Duc, Nguyen, Ngo Huu Hao, and Yoon Yong Soo. “A New Hybrid
Treatment System of Bioreactors and Electrocoagulation for Superior Removal
of Organic and Nutrient Pollutants from Municipal Wastewater.” Elsevier Ltd.
(November 27, 2013).
http://www.sciencedirect.com/science/article/pii/S0960852413017641.
3Kasem, Chunkao, Nimpee Chatri, and Duangmal Kittichai. “The King’s Initiative
Using Water Hyacinth to Remove Heavy Metals and Plant Nutrients from
Wastewater through Bueng Makkasan in Bangkok, Thailand.” Elsevier B.V.
(December 16, 2011).
http://www.sciencedirect.com/science/article/pii/S0925857411003028.
4Kumiko, Oguma, Kita Ryo, Sakai Hiroshi, Murakami Michio, and Takizawa
Satoshi. “Application of UV Light Emitting Diodes to Batch and Flow-through
Water Disinfection Systems.” Elsevier B.V. (September 14, 2013).
http://www.sciencedirect.com/science/article/pii/S0011916413003792.
5Ying, Sun, Zheng Jianchang, Zou Luquan, Liu Qiang, Zhu Ping, and Qian
Guangren. “Reducing Volatilization of Heavy Metals in Phosphate-Pretreated
Municipal Solid Waste Incineration Fly Ash by Forming Pyromorphite-like
Minerals.” Elsevier Ltd. (November 5, 2010).
http://www.sciencedirect.com/science/article/pii/S0956053X10005350.