Page 201 - Membranes for Industrial Wastewater Recovery and Re-Use

170 Membranes for Industrial Wastewater Recovery and Re-use

Table 3.39 Highly puriRed water (non-cornpendial water)
Parameter Units USP 25 Ph. Eur. (bulk)
TOC ppb C 500
Conductivity pS/cm at < 1.1
20°C
Aerobic bacteria CFU/ml < 10
Bacterial EU/ml <0.25
endotoxins

and costs of water and effluent disposal increase, the latter being almost
inevitable.
It is nonetheless technically possible to reuse effluent at present to generate a
usable feed stream, especially given that around 45% of the wastewater is likely
to have an aggregate conductivity of well below 100 pS cm-l, based on the data
given in Table 3.39, and would thus actually dilute the mains water supply.
Much of the effluent produced from pharmaceutical processes has a limited range
of contaminants, namely only trace levels of the products being manufactured
and very low levels of salts and organics. Also, this effluent is much better
characterised and controlled than typical municipal-supplied drinking water,
since PW and WFI waters are very low in dissolved matter and the exact nature
of the impurities added are known. Consequently, it should be possible to
specifically monitor and, if necessary, selectively remove individual impurities
introduced from the production environment into the effluent to ensure that the
reclaimed water consistently meets the drinking water standard.
For example, PW typically has a conductivity < 1 pS cm-l, i.e. a total dissolved
solids concentration of around 0.5 mg 1-l. This content is largely made up of
sodium and chloride ions with traces of potassium, fluoride and other small
molecular weight ions. If this water is used in the final rinse of a process vessel
the only contaminants added will be residual quantities of the products being
manufactured, generally at levels < 1 mg 1-l. The actual quantities of these
products will be accurately measured and recorded as part of the validation of
the CIP process but will obviously vary between applications. The impurities
from other waste streams will generally be the same as those present in the feed
water but at much lower levels, and can be measured using the same analytical
methods as are used for potable water.
Water continues to be the most commonly used chemical in most
pharmaceutical operations and also continues to be one of the most problematic.
One of the largest causes for product recalls are water-related issues, and such an
environment imposes a considerable barrier to water recycling. If there is also no
strong economic driving force, regardless of the technical feasibility of water
recycling, it is unlikely to happen in this industry in the near future.