M.R. Alavi Moghaddam

Coagulation/flocculation process for dye removal using sludge from water treatment plant: Optimization through response surface methodology

In this study, performance of a waterworks sludge (FCS: ferric chloride sludge) for the removal of acid red 119 (AR119) dye from aqueous solutions were investigated. For this purpose, response surface methodology (RSM) was applied to optimize three operating variables of coagulation/flocculation process including initial pH, coagulant dosage and initial dye concentration. The results showed that the decrease of initial pH was always beneficial for enhancing dye removal and no re-stabilization phenomenon was occurred even at the used maximum FCS dosage. It seems that iron hydroxides of the FCS could neutralize the negative charges on dye molecules or cause to the trapping of the dye ones. Therefore, the sweep flocculation and/or the charge neutralization might play key roles in the enhancement of dye removal. The optimum initial pH, FCS dosage and initial dye concentration were found to be 3.5, 236.68 mg dried FCS/L and 65.91 mg/L, respectively. Dye removal of 96.53% is observed which confirms close to RSM results. Therefore, it can be concluded that reusing the FCS as a low-cost material into the coagulation/flocculation process in wastewater treatment plants can offer some advantages such as high efficiency for AR119 dye removal and economic savings on overall treatment plant operation costs.

Evaluation of integrated anaerobic/aerobic fixed-bed sequencing batch biofilm reactor for decolorization and biodegradation of azo dye Acid Red 18: Comparison of using two types of packing media

Two integrated anaerobic/aerobic fixed-bed sequencing batch biofilm reactor (FB-SBBR) were operated to evaluate decolorization and biodegradation of azo dye Acid Red 18 (AR18). Volcanic pumice stones and a type of plastic media made of polyethylene were used as packing media in FB-SBBR1 and FB-SBBR2, respectively. Decolorization of AR18 in both reactors followed first-order kinetic with respect to dye concentration. More than 63.7% and 71.3% of anaerobically formed 1-naphthylamine-4-sulfonate (1N-4S), as one of the main sulfonated aromatic constituents of AR18 was removed during the aerobic reaction phase in FB-SBBR1 and FB-SBBR2, respectively. Based on statistical analysis, performance of FB-SBBR2 in terms of COD removal as well as biodegradation of 1N-4S was significantly higher than that of FB-SBBR1. Spherical and rod shaped bacteria were the dominant species of bacteria in the biofilm grown on the pumice stones surfaces, while, the biofilm grown on surfaces of the polyethylene media had a fluffy structure.

Coagulation/flocculation of dye-containing solutions using polyaluminium chloride and alum

This study aims to compare the performance of Polyaluminium Chloride (PAC) and alum as coagulants to remove a specific type of dye (Acid Blue 292 (AB292)) from dye-containing solution. For this purpose, the influence of pH, coagulant dosage, coagulant aids (kaolinite and bentonite), and initial dye concentration on dye removal efficiency were examined. According to the results, removal of AB292 was absolutely dependent on the pH variations. The maximum dye removal occurred when pH was 7 and 5 for PAC and alum, respectively. Both coagulants efficiently removed the dye (about 85%) with a relatively low dosage (40 mg/l) in their optimum pH range. By adding kaolinite as a coagulant aid, the removal efficiencies tended to increase, especially for lower dosages of PAC and alum. With the increase of initial dye concentration, PAC and alum represented different behaviors. In the case of PAC, Q (the amount of the removed dye per unit mass of coagulant) increased at first and reached to a maximum value, 2.1 mg dye/mg PAC, and then decreased rapidly. While for alum, Q steadily increased with the increase of dye concentration and reached to 2.8 mg dye/mg alum. No reduction of Q occurred for alum with the increase of dye concentration in the range of 25-250 mg/l.

Post-treatment of anaerobically degraded azo dye Acid Red 18 using aerobic moving bed biofilm process: Enhanced removal of aromatic amines

The application of aerobic moving bed biofilm process as post-treatment of anaerobically degraded azo dye Acid Red 18 was investigated in this study. The main objective of this work was to enhance removal of anaerobically formed the dye aromatic metabolites. Three separate sequential treatment systems were operated with different initial dye concentrations of 100, 500 and 1000 mg/L. Each treatment system consisted of an anaerobic sequencing batch reactor (An-SBR) followed by an aerobic moving bed sequencing batch biofilm reactor (MB-SBBR). Up to 98% of the dye decolorization and more than 80% of the COD removal occurred anaerobically. The obtained results suggested no significant difference in COD removal as well as the dye decolorization efficiency using three An-SBRs receiving different initial dye concentrations. Monitoring the dye metabolites through HPLC suggested that more than 80% of anaerobically formed 1-naphthylamine-4-sulfonate was completely removed in the aerobic biofilm reactors. Based on COD analysis results, at least 65-72% of the dye total metabolites were mineralized during the applied treatment systems. According to the measured biofilm mass and also based on respiration-inhibition test results, increasing the initial dye concentration inhibited the growth and final mass of the attached-growth biofilm in MB-SBBRs.

Techno-economical optimization of Reactive Blue 19 removal by combined electrocoagulation/coagulation process through MOPSO using RSM and ANFIS models

In this research, Response Surface Methodology (RSM) and Adaptive Neuro Fuzzy Inference System (ANFIS) models were applied for optimization of Reactive Blue 19 removal using combined electrocoagulation/coagulation process through Multi-Objective Particle Swarm Optimization (MOPSO). By applying RSM, the effects of five independent parameters including applied current, reaction time, initial dye concentration, initial pH and dosage of Poly Aluminum Chloride were studied. According to the RSM results, all the independent parameters are equally important in dye removal efficiency. In addition, ANFIS was applied for dye removal efficiency and operating costs modeling. High R(2) values (≥85%) indicate that the predictions of RSM and ANFIS models are acceptable for both responses. ANFIS was also used in MOPSO for finding the best techno-economical Reactive Blue 19 elimination conditions according to RSM design. Through MOPSO and the selected ANFIS model, Minimum and maximum values of 58.27% and 99.67% dye removal efficiencies were obtained, respectively.

Successful treatment of high azo dye concentration wastewater using combined anaerobic/aerobic granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR): simultaneous adsorption and biodegradation processes

The application of a granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR) for treatment of wastewater containing 1,000 mg/L Acid Red 18 (AR18) was investigated in this research. The treatment system consisted of a sequencing batch reactor equipped with moving GAC as biofilm support. Each treatment cycle consisted of two successive anaerobic (14 h) and aerobic (8 h) reaction phases. Removal of more than 91% chemical oxygen demand (COD) and 97% AR18 was achieved in this study. Investigation of dye decolorization kinetics showed that the dye removal was stimulated by the adsorption capacity of the GAC at the beginning of the anaerobic phase and then progressed following a first-order reaction. Based on COD analysis results, at least 77.8% of the dye total metabolites were mineralized during the applied treatment system. High-performance liquid chromatography analysis revealed that more than 97% of 1-naphthyalamine-4-sulfonate as one of the main sulfonated aromatic constituents of AR18 was removed during the aerobic reaction phase. According to the scanning electron microscopic analysis, the microbial biofilms grew in most cavities and pores of the GAC, but not on the external surfaces of the GAC.

Comparison of three combined sequencing batch reactor followed by enhanced Fenton process for an azo dye degradation: Bio-decolorization kinetics study

The purpose of this research was to compare three combined sequencing batch reactor (SBR) - Fenton processes as post-treatment for the treatment of azo dye Acid Red 18 (AR18). Three combined treatment systems (CTS1, CTS2 and CTS3) were operated to investigate the biomass concentration, COD removal, AR18 dye decolorization and kinetics study. The MLSS concentration of CTS2 reached 7200 mg/L due to the use of external feeding in the SBR reactor of CTS2. The COD concentration remained 273 mg/L and 95 mg/L (initial COD=3270 mg/L) at the end of alternating anaerobic-aerobic SBR with external feeding (An-A MSBR) and CTS2, respectively, resulting in almost 65% of Fenton process efficiency. The dye concentration of 500 mg/L was finally reduced to less than 10mg/L in all systems indicating almost complete AR18 decolorization, which was also confirmed by UV-vis analysis. The dye was removed following two successive parts as parts 1 and 2 with pseudo zero-order and pseudo first-order kinetics, respectively, in all CTSs. Higher intermediate metabolites degradation was obtained using HPLC analysis in CTS2. Accordingly, a combined treatment system can be proposed as an appropriate and environmentally-friendly system for the treatment of the azo dye AR18 in wastewater.

A comparison study on Acid Red 119 dye removal using two different types of waterworks sludge.

This study aims to compare the performance of two waterworks sludge samples, ferric chloride sludge (FCS) and polyaluminium chloride sludge (PACS), as coagulants to remove Acid Red 119 (AR119) dye from aqueous solution. A series of batch experiments were performed to investigate the effect of initial pH, coagulant dosage and initial dye concentration on coagulation/flocculation process efficiency. Results showed that the dye removal was strongly pH-dependent and followed the same trend for both coagulants, increasing steadily with decreasing initial pH in the range of 3-12. With the increase of coagulant dosage, the dye removal efficiency increased and no re-stabilization phenomenon was observed. However, the coagulant dosage needed for the maximum dye removal efficiency was much lower for FCS (150 mg dried sludge/L) in compare with PACS (5.5 g dried sludge/L). It seems that both charge neutralization and sweep flocculation mechanisms were involved in removal of AR119 using FCS and PACS. With the increase of initial dye concentration, Q (the amount of the removed dye per unit mass of coagulant) steadily increased and reached to a maximum value of 0.96 mg dye/mg sludge and 0.029 mg dye/mg sludge for FCS and PACS, respectively. FCS was more effective than PACS for AR119 dye removal due to the higher amount of dye removed per unit mass of sludge.

Study on the removal of acid dyes using chitosan as a natural coagulant/coagulant aid

Chitosan was selected as a natural coagulating agent for the removal of acid dyes (Acid Blue 292; AB292, and Acid Red 398; AR398) from dye-containing solutions. The study was organised in two phases. In phase 1, chitosan was used alone as a natural coagulant for the removal of the dyes. For this purpose, the effect of different parameters including pH, chitosan dosage and initial dye concentration on the dye removal efficiency was examined. In phase 2 of the study, the application of chitosan as a natural coagulant aid in conjunction with polyaluminium chloride (PAC) was assessed. According to the results of phase 1, the best removal efficiencies occurred in an acidic pH range (less than 6) for both of the dyes. Also, excellent dye removal results (about 90%) were achieved with relatively low dosages of chitosan (30-35 mg L(-1) for AB292 and 50-60 mg L(-1) for AR398). However, the initial concentration of the dyes severely influenced the coagulation performance of chitosan, which can constrain the performance of chitosan as a natural coagulant. On the basis of the results of phase 2, chitosan, as a natural coagulant aid, noticeably enhanced the dye removal efficiency of PAC, especially in the case of AB292. Small amounts of chitosan (3 or 5 mg L(-1)) enhanced the dye removal efficiency of PAC up to 2.5 times for AB292.

The Role of Environmental Engineering Education in Sustainable Development in Iran: AUT Experience.

Purpose – The aim of this paper is to explain the strategies and activities of a main technical University in Iran (Amirkabir University of Technology (AUT)) toward sustainable development goals.Design/methodology/approach – In this paper, three main strategies of AUT to achieve sustainable developments goals in engineering education are explained. In addition, the main obstacles of these programs including the budget limitation for implementation of main activities related to sustainable development and difficulties in official procedure for the change of educational system is also explained.Findings – The study of strategies and activities of a university can provide useful information for other universities (especially in developing countries) that like to promote their activities toward sustainable development goals. According to the final results, international education of engineering students and teachers, especially those who are living in developing countries, have an important role in promoting ...