Integrated water recycling and emission abatement in the textile industry

• Research unit: EU RFP
• Project number: 96.0350

Key words (English)

Membrane concentrates; design; testing and modeling of reactors; industrial pollutants pretreatment; catalytically active membranes; pre-treatment economics

Alternative project number (English)

EU project number: ENV4-CT95-0064

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.1 Environment

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise:
EPF Lausanne
Institut de chimie physique
Laboratoire de photonique et interfaces

Partners and International Organizations (English)

CIDA, Fino Morgnasco (I), CNR-IRSA, Bari (I), Pontypridd (UK)

Abstract (English)

During this project the non biodegradable real effluents of textile plants as well as selected industrial textile dyes (Orange II, Remazol Brilliant Blue, Methylene Blue) were pretreated in the dark and under light by different homogeneous and heterogeneous methods. The de-coloration/degradation was designed, followed and modelized in reactors with a capacity to handle up to 20 m3/day. The cost to pretreat and decolorize for real effluents consisting of micelles, low molecular weight organics and dyes until they attain bio compatibility was seen to oscillate between 0.40 and 3 US/m3. This calculation takes into account the electricity cost and the material cost of the oxidant -in the main H202- which is the highest cost component of the entire process. No investment or labor cost is considered. Modelization of six or more simultaneous variables was found to be necessary to optimize the energy, time and materials component during the pollutant abatement process. Modelization through the Doehlert theorem (polynomial and exponential single expression via reduced dimensionless variables) allowed the optimization of the degradation/de-coloration for each of the systems considered. But kinetic modelization as well as surface modelization were developed as auxiliary tools for the detailed and comprehensive study of the abatement processes under consideration. Synthetic effluents made up by specific dyes in the presence of chlorides -a known OH-radical scavenger- revealed to be necessary to understand processes occurring in more complex or multicomponent systems. The main results obtained in this project are stated below:
The development of artificial catalytic stable membranes (>3000 hours of testing) active in the generation of highly reactive and oxidative radicals in solution to abate the pollutants upon oxidant addition avoiding the post-treatment elimination of suspensions or ionic-species in solution. This last step involves labor and material costs that pose a problem in large scale operation. The use of catalytic membranes allows to treat effluents by Fenton reactions up to pH 6-7 in cases that homogeneous solutions show only an acceptable kinetic rate at pH values <3.6
The use of 02 as an oxidant in certain cases when the oxido-reduction potential of the excited state of the dye lorganic pollutant allows it under low cost visible light excitation. 02 is the cheapest industrial oxidant at 50 US/ton and has been applied in our laboratory successfully in the case of textile dyes.
The observation and mechanistic details of surface molecular recognition during abatement processes as a consequence of ligand exchange processes between the pollutant and the catalyst surface.
The initial study of halocarbon degradation always present in textile waste water effluents finding new catalysts and efficient membrane mediated light activated to degrade these pollutants in laboratory scale reactors in cost efficient processes.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 96.0350