Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Anaerobic Treatment of Textile Dyeing Wastewater (within extra work agreed on in the last meeting, combining workpackages) Lettinga Associates Foundation

TOWEF0 - Paris - October 2003 Work packages integrated WP (Centexbel) –Tests for water reuse WP (LeAF) –Tests by anaerobic bioreactor WP (ENEA) –Membrane tests to produce reusable water

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Overall experiment

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 The part of LeAF Anaerobic pre-treatment of dyeing wastewater for membrane treatment with the objective of reuse Treatment of two streams: –Reactive dyeing and acid dyeing wastewater Recording of respirograms of water from the different treatment stages

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Previous presentation Project meeting in March: Results of the continuous experiment were presented

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Memory refresher - some of the conclusions Reactor set-up was not optimal Passing all effluent twice through the reactors did improve colour removal for acid dyeing, not for reactive dyeing Size waste seems a suitable co- substrate for anaerobic decolourisation

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 What is new? Batch experiments conducted to get more insight in anaerobic treatment of the same two wastewaters –Comparison treatment at 30ºC / 55ºC –Application of electron mediator to whether performance can be improved Respirograms

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Batch experiments Bottles of 120 ml Filled with 50 ml wastewater Headspace N2-CO2 (70%-30%) At 30ºC with size as co-substrate At 30ºC and 55ºC with VFA/Glucose In presence and absence of AQS as electron mediator

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Electron mediation Biological reduction of dyestuffs is non- specific process Usually slow, mediator accepts electron faster and transfers it to dye molecule Widely tested with single azo dyes, little known about effect in real wastewaters

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Azo dye reduction Next: electron mediator is AQS (AnthraQuinone-2-Sulphonate)

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Mediated azo dye reduction

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Reactive dyeing - thermo/meso O = Chemical control  = Sludge+ww+VFA/Glucose  Sludge+ww+VFA/G+AQS 420 & 500 nm610 nm

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Reactive dyeing 420 and 500 nm: results as expected –Thermophilic incubations show faster decolourisation –AQS speeds up decolourisation rates 610 nm: unexpected behaviour –all incubations have the same rate, although thermophilic bottles reach better final decolourisation

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Acid dyeing - thermo/meso O = Chemical control  = Sludge+ww+VFA/Glucose  Sludge+ww+VFA/G+AQS 475 nm620 nm

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Example of acid dyeing spectra (Mesophilic incubation with co-substrate and AQS)

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Acid dyeing 620 nm: Mesophilic results as expected –Thermophilic is faster, but AQS has no effect –AQS has effect under mesophilic conditions 475 nm: unexpected behaviour –Decolourisation lines are chaotic, but: –When looking at spectra, product formation can be seen for incubations with AQS

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Additional results Size waste vs VFA/Glucose mixture –No significant differences (both wastewaters) –Size waste is an interesting co-substrate Formation of precipitates after time –After 14 days acid dyeing controls (chem. control & sludge+ww) suddenly decolourised. Dark blue flocs had been formed. –In biologically active bottles (+Co / Mediator) there were also flocs, but grey.

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Conclusions Thermophilic treatment is advantageous –Most dyeing effluent is hot, no need to cool down –Faster than at 30ºC with mediator Decolourisation depends on dye type –Chosen wavelengths represent different dyes –In this way different behaviour can be followed –Important to know dye structures beforehand to be able to draw conclusions

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Conclusions Electron mediator –Can largely increase decolourisation rate and improve final colour for mesophilic treatment –Does not work for all dye types Need for more knowledge on: –behaviour of different dye types in anaerobic treatment under different conditions –effect of mediators in different kinds of real wastewater to assess their potential

Lettinga Associates Foundation TOWEF0 - Paris - October 2003 Integration batch/continuous Reactive dyeing: –Batch results comparable with reactor results in first days of reactor operation Acid dyeing: –Batch results better than reactor results –Improvement of colour removal when using effluent as influent probably due to mechanical filtration of precipitates formed in effluent during storage