Page 172 - Membranes for Industrial Wastewater Recovery and Re-Use

Industrial waters 145

Table 3.28 Average process water quality for textile finishing (Mattioli et d., 2002)
Parameter Lake Ground Reclaimed" Guide value
TSS, mg/l <1 10 22 10
COD, mg/l < 10 30 53 30
W abs. 420 nm < 0.001 < 0.001 0.02 0.01
PH 7.8 7.5 7.7 7-8
Conductivity, pS/cm 290 200 1600 1800
a Reclaimed from tertiary-treated wastewater (Section 3.1.7).

bleaching, mercerising, dyeing, printing, resin treatment water proofing, flame
proofing, soil repellency application, and special finish application.
Effluent limitations representing the degree of effluent reduction attainable by
using either best practicable control technologies (BPT), or best available
technologies (BAT) are given for all subcategories. BPTs are used for
discharges from existing point sources to control conventional and non-
conventional pollutants as well as some priority pollutants. BATs are used to
control priority pollutants and non-conventional pollutants when directly
discharged into environmental waters. BPT limits for BOD, COD, TSS, sulphide,
phenol, total chromium, and pH are set for every category (Subpart), with the
exception of Subpart C (Low Water Use Processing Subcategory). Each subpart,
with the exception again of Subpart C, also has BAT limits for COD, sulphide,
phenols, and total chromium. New source performance standards (NSPS) for
BOD, COD, TSS, sulphide, phenols, total chromium, and pH are set for each
subcategory. However, for the woven fabric finishing subcategory (Subpart D),
the NSPSs are divided into process-specific standards that differ according to the
manufacturing operation. The NSPS levels (Table 3.29) are based on mass
emission rather than concentration.
The USEPA has also recently developed values for factors related to effluent
generation load factors (i.e. mass flow of pollutant per based on unit production)
to enable estimation of the effluent load from different textile mills (Table 3.30).
In the absence of actual data, these estimates provide some guideline to estimate
the extent of environmental impact. Existing textile mills, on the other hand, are
able to use this data for benchmarking.

Europe
European legislation is less prescriptive than that of the USEPA, but nonetheless
is based on the same principle of BAT. The key European directive is 96/61
Integrated Pollution Prevention and Control, which requires both industrial
plant operators and regulators to take an integrated, holistic view of the
pollution and resource demand potential of the installation. Central to this
approach is appropriate preventative measures against pollution, specifically
through the application of the BAT principle to improve environmental
performance (Dulio, 2001). It is then left to the individual member states to
define BATs, but these must obviously focus on waste minimisation and,
ultimately, closed-loop options for industrial water use.