Water Reuse at the
Celulosa Y Derivados, S. A. Plants
HECTOR J. GOMEZ, Plant Manager
Copropiedad Grupo Quimico Cy DSA
Avenue, Ruiz Cortinez, Al PTE
Monterrey, N. L., Mexico
INTRODUCTION
Mexico, like many other countries, has large desertic and semi desertic areas.
The scarcity of water in these regions has warranted the installation of waste water
treatment plants to reclaim the water for industrial uses, thus preserving the small
amounts of fresh water for cities --or more important needs. We find an example
of this in the city of Monterrey, Mexico, which has five privately owned and operated sewage water reclamation plants, treating around 60 per cent of the city's
waste water, with the purpose of using the final effluent to supply water for at
least 30 different industries.
CELULOSA Y DERIVADOS, S. A.
Celulosa was the first industry which decided in 1954 to purify the domestic
waste water and use it to support its manufacturing operations and to provide for
the quantity of water needed for its future growth.
During the early part of this decade, Celulosa was merged to integrate an
Industrial Center called Grupo Quimico Cydsa, and is formed by the following
plants: Celulosa y Derivados, S. A.; Fibras Qui micas, S. A. and Quimobasicos,
S. A.
At the same time occurred the formation of Copropiedad Grupo Quimico
Cydsa, a non profitable organization in charge of providing water, steam and part
of the electricity necessary for the process that includes the manufacture of: Rayon,
Nylon, Transparent Paper, Caustic Soda, Chlorine, Sulfuric Acid, Hydrochlorine
Acid, Hydrofluoric Acid, Carbon Disulfide, Carbon Tetrachloride, Sodium Sulfate, Sodium Sulfite.Refrigerant Gases, etc.
WASTEWATER TREATMENT
The raw sewage from the residential section arrives at the treatment plant by
gravity through a 24 in.  sewer line 10 miles long.
Arriving at the plant the raw sewage is pumped into a holding tank, which
has a capacity of half a million gallons and a detention time of 4. 0 hrs. This
holding tank is intended to avoid variations of both flow and chemical composition.
After the holding tank, the raw sewage is fed into a conventional activated
sludge treatment plant which has a capacity of 2.2 MGD. Then, the final effluent
is pumped into a pond which has a capacity of 7, 500, 000 gals.   After chlorina-
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