Anam Asghar

Wastewater-based microbial fuel cell is a promising green technology that can potentially be used to treat recalcitrant wastewater such as textile wastewater through in situ Fenton oxidation while generating net positive energy. One of the main features of this technology is the use of membranes for isolating the cathode chamber for in situ H2O2 production (thus in situ Fenton oxidation). The challenges in this technology include membrane fouling and resistance, pH splitting, oxygen diffusion, substrate crossovers, effect of Fenton’s reagents and high cost of commercially available membranes. Therefore, this paper critically analyzes each challenge in detail to access their direct or indirect effects on the overall performance. Exploration of new materials and modifications of existing materials has produced cost-efficient and reliable membranes. However, their application in in situ Fenton oxidation has not been demonstrated. It is concluded that the use of membranes with high hydrophilicity, small pore size and materials enriched with sulfonated groups is suitable for in situ H2O2 production in the cathode chamber. Moreover, use of cleaning agents such as H2O2 or H2SO4 recovers the membrane performance for in situ H2O2 production. Thus, it offers a green technology because in situ H2O2 can be used for membrane cleaning and energy produced can be used for aeration of the cathode chamber.

Fenton Process, a type of Advanced Oxidation Processes is an efficient method for treating textile
wastewaters. However, excessive use of hydrogen peroxide and catalyst has made this process
economically non-feasible. Besides, industrial grade hydrogen peroxide costs $390 e500 per ton. One of
the means to overcome this problem is the in-situ production of hydrogen peroxide. In this paper, a
detailed review was conducted on the generation methods, degradation potential and optimum operating parameters for in-situ production of hydrogen peroxide/hydroxyl radicals. Additionally the scavenging aspect for hydroxyl radicals was also investigated. From this review, it can be concluded that
hydroxyl radical is highly oxidative and non selective in nature and its in-situ production can be performed through application of catalyst, ozonation, photocatalysis, electro and microbial fuel cells.
Furthermore, optimization of operating parameters can result in an increase in the yield of hydroxyl
radicals/hydrogen peroxide. Sonolysis as an auxiliary tool has potential to induce synergetic effects in
combination with Advanced Oxidation Processes to increase in-situ hydrogen peroxide production.
However, the problem of the scavenging effect is an aspect that needs to be dealt with, as hydroxyl
radicals are prone to deactivation by scavengers. Therefore based on the review, it is concluded that insitu production of hydrogen peroxide/hydroxyl radical for treating textile wastewater is economically
viable and practically feasible if careful selection of process is conducted through selective research

In the present study, a comparison of central composite design (CCD) and Taguchi method was established for Fenton oxidation.
[Dye] ini, Dye : Fe+2, H2O2 : Fe+2, and pH were identifid control variables while COD and decolorization effiency were selected
responses. 𝐿 orthogonal array and face-centered CCD were used for the experimental design. Maximum 99% decolorization and
80% COD removal effiency were obtained under optimum conditions. � squared values of 0.97 and 0.95 for CCD and Taguchi
method, respectively, indicate that both models are statistically signifiant and are in well agreement with each other. Furthermore,
Prob > � less than 0.0500 and ANOVA results indicate the good fiting of selected model with experimental results. Nevertheless,
possibility of ranking of input variables in terms of percent contribution to the response value has made Taguchi method a suitable
approach for scrutinizing the operating parameters. For present case, pH with percent contribution of 87.62% and 66.2% was ranked
as the most contributing and signifiant factor. Ths fiding of Taguchi method was also verifid by 3D contour plots of CCD.
Threfore, from this comparative study, it is concluded that Taguchi method with 9 experimental runs and simple interaction plots
is a suitable alternative to CCD for several chemical engineering applications

Application of the Fenton process for textile wastewater treatment is limited due to high treatment cost, substantially contributed by the un-availability of cheap hydrogen peroxide. Therefore, alternative methods for hydrogen peroxide production
are in demand. One such option is in situ hydrogen peroxide production using a wastewater based microbial fuel cell (WBMFC).
However, not much have been published regarding in situ production of hydrogen peroxide for textile wastewater treatment in
a WBMFC. Therefore, in this work the concept, advantages, challenges and prospects of using WBMFC to treat textile wastewater by simultaneously producing hydrogen peroxide (hence in situ hydrogen peroxide) and power are reviewed. The concept
of WBMFC is the reduction of oxygen in the presence of electrons and protons from the anode chamber to produce hydrogen
peroxide with simultaneous power production. This review confirms that use of dual chambers, proton exchange membrane,
domestic or municipal wastewater/Geobacter Sulfurreducens or Shewanella species, pure graphite cathode, ammonia and heat
treated carbon-based anode can treat most textile wastewaters. However, single chamber WBMFCs can be used as a low power
source for an electro-Fenton reactor. Power produced can be used to provide energy for aeration required in the WBMFC, thus
providing an integrated and sustainable solution for textile wastewater treatment.