Page 197 - Membranes for Industrial Wastewater Recovery and Re-Use

1 66 Membranes for Industrial Wastewater Recovery and Re-use

USP 2 5, there is similarly no stipulation of process for PW production. Organic
carbon measurement can be by TOC, a combustion-based instrumental method,
or by permanganate value (PV).
Sterilised water for injection is used for dissolving or diluting substances or
preparations for parenteral administration. Water for injection in bulk is used in
the manufacture of parenteral and ophthalmic products. It is also used for final
rinsing of containers (e.g. primary packaging materials) and manufacture of
these products. In addition to stipulations concerning quality (Table 3.3 7)
and quality control, the EP 2000 stipulates that the water must be produced
by distillation. The USP 25, on the other hand, permits both distillation and
reverse osmosis.
Potable water, or water intended for human consumption, is also used as
feedwater for the production of purified water. Potable water may be used to
rinse product-contacting surfaces of equipment. Treated potable water has the
same uses as potable water and water intended for human consumption but has
been treated to reduce its microbial content. Finally, highly purified water (non-
compendia1 water) is used in the preparation of medicinal products where
bacterial endotoxins need to be controlled, except where water for injection is
required. Current methods for the preparation include double-pass reverse
osmosis, reverse osmosis combined with ultrafiltration and distillation.
While the punty levels specified for PW and WFI are not as high as those
required in industries such as electronics and power station water systems (Table
1, l), the control of the quality and the documentation related to the system are
of paramount importance. In an extreme case, if the quality of water is not
achieved a patient may ultimately die when being treated with medication
manufactured using that water. Consequently, the pharmaceutical industry
invests enormous sums of money to “validate” water systems, a process that
continues throughout the life of each water system.
Give that control of product water quality is crucial in this industry, control of
feedwater quality is similarly important. The USP includes a section that gives
general information on water for pharmaceutical purposes. This section
describes different types of water used, i.e. Drinking Water, Purified Water,
Sterile Purified Water, Water for Injection, Sterile Water for Injection,
Bacteriostatic Water for Injection, Sterile Water for Irrigation and Sterile Water
for Inhalation. It begins with the statement that the feedwater used for
pharmaceutical preparations needs to be of potable water quality, meeting the
requirements of the National Primary Drinking Water Regulations (NPDWR)
(40 CFR 141) issued by the Environmental Protection Agency (EPA), since this
“ensures the absence of coliforms”. It is also pointed out, however, that meeting
the National Drinking Water Regulations does not rule out the presence of other
microorganisms, which, while not considered a major public health concern
could, if present, constitute a hazard or be considered undesirable in a drug
substance or formulated product.
The stipulation of compliance with the national potable water standards is
critical, and effectively severely constrains recycling opportunities. This ensures
that the level of impurities, inorganic, organic and bacterial, that can be present