A. Bes-Piá

Reuse of wastewater of the textile industry after its treatment with a combination of physico-chemical treatment and membrane technologies

This work is focused on the treatment of a textile plant wastewater. The industry mainly manufactures socks, stockings and panties, and the water is treated in order to be reused. The wastewater was characterized and jar-tests experiments were carried out with different coagulants and flocculants, at different concentrations and pH in order to obtain clarified water that can be treated by means of ultrafiltration (UF) or nanofiltration (NF). The combination of the physico-chemical treatment and the nanofiltration leads to a COD removal of almost 100%.

Combination of physico-chemical treatment and nanofiltration to reuse wastewater of a printing, dyeing and finishing textile industry

Abstract The main goal of this work was to study the feasibility of the combination of physico-chemical treatment with nanofiltration to reuse wastewater of a printing, dyeing and finishing textile industry. For the physico-chemical treatment two coagulants (one containing Al3+ and another containing Fe2+) were compared by carrying out jar-tests using different chemical concentrations and pH values. After that, nanofltration experiments with physico-chemically treated wastewater were performed at different operating pressures and cross-flow velocities. The results showed that the COD and conductivity of the nanofiltration permeates were lower than 100 mg/L and 1000 μS/cm respectively.

Application of multicriteria decision analysis to jar-test results for chemicals selection in the physical-chemical treatment of textile wastewater.

Jar-test is a well-known tool for chemicals selection for physical-chemical wastewater treatment. Jar-test results show the treatment efficiency in terms of suspended matter and organic matter removal. However, in spite of having all these results, coagulant selection is not an easy task because one coagulant can remove efficiently the suspended solids but at the same time increase the conductivity or increase considerably the sludge production containing chemicals and toxic dyes. This makes the final selection of coagulants very dependent on the relative importance assigned to each measured parameter. In this paper, the use of multicriteria decision analysis (MCDA) is proposed to help on the selection of the coagulant and its concentration in the physical-chemical wastewater treatment, since textile wastewater contains hazardous substances. Therefore, starting from the parameters fixed by the jar-test results, these techniques will allow to weight these parameters, according to the judgements of wastewater experts, and to establish priorities among coagulants. Two well-known MCDA techniques have been used: analytic hierarchic process (AHP) and preference ranking organization method for enrichment evaluations (PROMETHEEs) and their results were compared. The method proposed has been applied to the particular case of textile wastewaters. The results obtained show that MCDA techniques are useful tools to select the chemicals for the physical-technical treatment.

Comparison between nanofiltration and ozonation of biologically treated textile wastewater for its reuse in the industry

This work is focused on the advanced treatment of the biologically treated wastewater of a textile plant. Nowadays the factory effluent is treated by an activated sludge process carried out after the wastewater neutralization. The wastewater treatment plant effluent is not still appropriate for its reuse because of the residual COD and conductivity. Both nanofiltration experiments at different operating conditions and oxidation reactions with ozone and ozone/UV irradiation were performed to evaluate the final water quality for its reuse.

Study of the behaviour of different NF membranes for the reclamation of a secondary textile effluent in rinsing processes

More demanding legal regulations for the wastewater disposal and water scarcity make necessary wastewater reuse in the industry. In particular, textile industry generates large amounts of wastewater with a high concentration of pollutants. Even though present biological or physical-chemical treatments are broadly in place, the quality of the final effluent is not good enough to allow its direct reuse. Consequently, a complementary membrane process is required in order to improve wastewater characteristics. In this work, six NF membranes were tested at different volume concentration factors in order to select the most appropriate one. The main studied criteria were the permeate quality for its reuse in the textile processes and the minimum membrane fouling effect. The different results obtained for the tested membranes were explained by membrane characterization parameters as contact angle, roughness and size exclusion. Taking these factors into consideration, TFC-SR2 has shown the overall best results because of the high permeate flux and the minimum fouling (in terms of the normalised flux reduction).

Reducing the Pollution from Tanneries by Process Wastewater Reuse and Membrane Technologies

Tanneries generate large amounts of wastewaters that are characterized by high concentrations of organic matter, suspended solids, and sulfates. Then, reducing of water consumption and minimizing the pollution of the effluents are of paramount importance. In this chapter, firstly, a characterization of the effluents of a typical tannery producing leather from bovine hides is carried out. Afterward, the reuse of different residual floats is discussed by studying the environmental benefit and the possible effects on the final product quality. Finally, the implementation of membrane technologies is evaluated. For that, the use of membrane for the treatment of particular effluents from tanneries is reviewed, and after that, some practical experiences are discussed.

The role of the operating parameters of SBR systems on the SMP production and on membrane fouling reduction

In this work, six identical laboratory SBRs treating simulated wastewater were operated in parallel studying the effect of three food-to-microorganisms ratio (F/M ratio; 0.20, 0.35 and 0.50 kg COD·kg MLSS-1·d-1), two hydraulic retention times (HRT; 24 and 16 h) and two values of number of cycles per day (3 and 6). Influence of these operational parameters on the SMPs production and reactor performance, were studied. Results indicated that the highest F/M ratio, HRT and cycles/day produced 72.7% more of SMP. In a second experimental series, biological process yielding the maximal and the minimal SMPs production were replicated and both mixed liquors (ML) and treated effluents were ultrafiltrated. The flux decay in the conditions of minimum and maximum SMPs production were 52% and 72%, when the SBRs effluents were ultrafiltrated while no significant differences in the ultrafiltration of ML were found. In terms of permeability recovery, this was lower for the case of the ML (73% and 49% of initial permeability recovered for effluent and ML ultrafiltration, respectively).

Pretreatment and filterability tests of wastewater as a first step to characterize the influent to a membrane bioreactor

Abstract Wastewater reclamation and reuse has become one of the most important environmental issues nowadays. Thus, municipal wastewater treatment plants are being upgraded converting conventional activated sludge processes into membrane bioreactors in order to improve the quality of the treated wastewater. However, operational costs increase because of higher energy consumption and membrane fouling. Wastewater composition is one of the factors affecting membrane fouling, though its influence is difficult to describe. In this work, a study about wastewater pretreatment and filterability has been carried out in view of achieving valuable information for a further implementation of a membrane bioreactor. Experiments were performed with samples of four municipal wastewater treatment plants taken from the plant influent, the biological process influent and the plant effluent. Fiterability was evaluated by membrane filtration resistances using the resistance in series model. Resistances were measured with ultr...