Granulated biomass fly ash coupled with fenton process for pulp and paper wastewater treatment

Adsorption - Advanced oxidation process (AAOP) for the heavy metals and organic matter removal from leachate using combined filtration -Fenton's and Photo-Fenton's treatment

Design of cost - effective filtration unit was carried out to evaluate the efficiency of different filter media made of locally available materials to treat raw leachate. Four different filter media laterites, peat, bagasse and a mixture of all were considered as study filter media for the removal of Zinc, Nickel, Copper and Lead from raw leachate. The reactor exhibited a significant removal efficiency when the three-filter media were combined as a combination. A removal rate of around 83.0% and 64.12% was found for nickel and copper, respectively, with a combined filter medium. The order of heavy metal removal varied depending on the kind of filter media used. For combined filter media, the sequence was Ni > Cu > Pb > Zn. For bagasse filter media, it was Pb > Cu > Zn > Ni. For peat filter media, it was Ni > Cu > Pb > Zn. For laterite filter media, it was Zn > Cu > Ni > Pb. Insignificant removal of heavy metals was observed with bagasse in the current investigation and hence is not recommended for use as a filter medium. Pre-treated leachate was subjected to Fenton's oxidation and UV-Fenton's oxidation for organic matter removal. Green synthesized bleached laterite iron nanoparticles were used as a catalyst in the Fenton treatment. COD removal of 80.0% and 85.0% was observed with 0.5 g/L of nano iron catalyst and 500 mg/L of H2O2 and 100 mg/L of H2O2 on Fenton's oxidation and UV-Fenton's oxidation respectively. The synthesized particles were demonstrated to possess a catalytic function in the reduction of COD. Both Fenton's oxidation and UV-Fenton's oxidation exhibit pseudo-first-order kinetics with linear regression.

Recent advances of copolymer for water treatment

Increasing water pollution due to anthropogenic activities prompts the quest for an effective water treatment method. Polymeric materials have gained attention as adsorbents for water purification. Membranes are majorly made from homopolymeric materials. However, recent studies have focused on using copolymeric materials for improved performance. In this review, the basics of copolymerization including various types of copolymers, synthetic approaches, and their applications in various water pollutants removal are discussed in detail. Advances in water treatment technology using copolymeric materials as adsorbent/membranes in the last 4 years are covered with insights into the future outlook and areas of improvement in terms of copolymer composites for water treatment. Studies from the literature did not only reveal effectiveness of copolymer as a flocculant/antifouling materials and in removal of selective toxic metals, oil, and microbes but also demonstrated recyclability of the copolymer sorbents/membrane. Full exploration of unique copolymer textural and structural properties could lead to great advancement in water treatment process. PRACTITIONER POINTS: The copolymer types and synthetic methods are discussed. Application of copolymer as adsorbent/membranes for water treatment is presented. Recent advances show good pollutants removal for toxic metals, oil, and organics. Copolymer composites have great potential as adsorbent/membranes for future use in water treatment processes.

A Fenton-based approach at neutral and un-conditioned pH for recalcitrant COD removal in tannery wastewater: Experimental test and sludge characterization

The combination of raw animal skin manufacturing processes involves the use of large amounts of chemicals, resulting in the generation of complex and highly polluted tannery wastewater. In this context, the high concentration of chloride in tannery wastewater represents a crucial bottleneck. Indeed, sodium chloride, commonly used in tannery industry to prevent skin rot, increases the concentration of chlorides up to 50 %. At the same time, most of the advanced oxidation processes usually employed in tannery wastewater treatment to remove recalcitrant COD involve the use of conditioning agents, thus increasing the overall concentration of chlorides in the treated effluent. The aim of this study was to evaluate the electrochemical peroxidation process (ECP) efficiency in the treatment of tannery wastewater without changing pH, to improve Fenton technology by avoiding the use of chemicals. The influence of different electric currents on COD and color removal was investigated. The characterization of the produced sludge was conducted through FTIR, SEM and XRD analysis, exploring the morphology and composition of precipitate, depending on the applied current. Although an electrical current of 750 mA yields the highest COD and color removal efficiency (69.7 % and 97.8 %, respectively), 500 mA can be considered the best compromise because of energy consumptions. Iron oxides and hydroxides were generated during the ECP process, playing the role of coagulants through the absorption of organic and inorganic contaminants. The consumption of energy increased as a function of time and applied current; however, cost analysis showed that the electrodes contributed the most to the total cost of the process. In authors' knowledge, the application of ECP process as a tertiary treatment for the removal of recalcitrant COD in tannery wastewater represents a novelty in the literature and the results obtained can be considered as the basis for scaling up the process in future research.

New insights into toxicity reduction and pollutants removal during typical treatment of papermaking wastewater

Papermaking wastewater contained various of toxic and hazardous pollutants that pose significant threats to both the ecosystem and human health. Despite these risks, limited research has addressed the detoxification efficiency and mechanism involved in the typical process treatment of papermaking wastewater. In this study, the acute toxicity of papermaking wastewater after different treatment processes was assessed using luminousbacteria, zebrafish and Daphnia magna (D. magna). Meanwhile, the pollution parament of the corresponding wastewater were measured, and the transformation of organic pollutant in the wastewater was identified by three-dimensional fluorescence and other techniques. Finally, the possible mechanism of toxicity variation in different treatment processes were explored in combination with correlation analyses. The results showed that raw papermaking wastewater displayed high acute toxicity to luminousbacteria, and exhibited slight acute toxicity and acute toxicity effect to zebrafish and D. magna, respectively. After physical and biochemical processes, not only the toxicity of the wastewater to zebrafish and D. magna was completely eliminated, but also the inhibitory effect on luminousbacteria was significantly reduced (TU value decreased from 11.07 to 1.66). Among them, the order of detoxification efficiency on luminousbacteria was air flotation > hydrolysis acidification > IC > aerobic process. Correlation analyses revealed a direct link between the reduced of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) and the detoxification efficiency of the different processes on the wastewater. In particular, the removal of benzene-containing aromatic pollutant correlated positively with decreased toxicity. However, the Fenton process, despite lowering TOC and COD, increased of the acute toxicity of the luminousbacteria (TU value increased from 1.66 to 2.33). This may result from the transformation generation of organic pollutant and oxidant residues during the Fenton process. Hence, oxidation technologies such as the Fenton process, as a deep treatment process, should be more concerned about the ecological risks that may be caused while focusing on their effectiveness in removing pollutant.

Reclamation of real textile wastewater by sequential advanced oxidation and adsorption processes using corn-cob based materials

Wastewater management has become crucial for sustaining biological life in the near future. One of the key aspects is integration of treatment processes aiming reuse of treated water for many purposes instead of water discharge. This study focused on combining two different methods, photo-Fenton-like oxidation, and adsorption, for treatment of real textile wastewater to improve water quality to be reused for irrigation. The real textile wastewater was collected from a local plant and subjected to photo-Fenton-like oxidation and adsorption as hybrid process. The operational parameters were optimized for each step by assessing the water quality according to the domestic regulations for irrigation water. The photo-Fenton-like oxidation itself was not successful to achieve the targeted water quality for reuse whereas adsorption as an additional step made the treated water reusable in terms of organic content. But the treated water still contained a certain amount of salinity due to extreme salt usage in textile processing. It was concluded that the treated water at the end of hybrid process could be used for salinity resistant plants such as sugar beet, barley, and cotton which demonstrates a promising contribution to the circular economy for biomass.

Degradation of sulfamethoxazole by super-hydrophilic MoS2 sponge co-catalytic Fenton: Enhancing Fe2+/Fe3+ cycle and mass transfer

To promote the cycle of Fe²⁺/Fe³⁺ in co-catalytic Fenton and enhance mass transfer in an external circulation sequencing batch packed bed reactor (ECSPBR), super-hydrophilicity MoS₂ sponge (TMS) modified by tungstosilicic acid (TA) was prepared for efficiently degrading sulfamethoxazole (SMX) antibiotics in aqueous solution. The influence of hydrophilicity of co-catalyst on co-catalytic Fenton and the advantages of ECSPBR were systematically studied through comparative research methods. The results showed that the super hydrophilicity increased the contact between Fe²⁺ and Fe³⁺ with TMS, then accelerated Fe²⁺/Fe³⁺ cycle. The max Fe²⁺/Fe³⁺ ratio of TMS co-catalytic Fenton (TMS/Fe²⁺/H₂O₂) was 1.7 times that of hydrophobic MoS₂ sponge (CMS) co-catalytic Fenton. SMX degradation efficiency could reach over 90% under suitable conditions. The structure of TMS remained unchanged during the process, and the max dissolved concentration of Mo was lower than 0.06 mg/L. Additionally, the catalytic activity of TMS could be restored by a simple re-impregnation. The external circulation of the reactor was conducive to improving the mass transfer and the utilization rate of Fe²⁺ and H₂O₂ during the process. This study offered new insights to prepare a recyclable and hydrophilic co-catalyst and develop an efficient co-catalytic Fenton reactor for organic wastewater treatment.