Effluents detoxification from pulp and paper industry using microbial engineering and advanced oxidation techniques

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.

Recent advances in eco-friendly technology for decontamination of pulp and paper mill industrial effluent: a review

The economic development of a country directly depends upon industries. But this economic development should not be at the cost of our natural environment. A substantial amount of water is spent during paper production, creating water scarcity and generating wastewater. Therefore, the Pollution Control Board classifies this industry into red category. Water is used in different papermaking stages such as debarking, pulping or bleaching, washing, and finishing. The wastewater thus generated contains lignin and xenobiotic compounds such as resin acids, chlorinated lignin, phenols, furans, dioxins, chlorophenols, adsorbable organic halogens (AOX), extractable organic halogens (EOCs), polychlorinated biphenyls, plasticizers, and polychlorinated dibenzodioxins. Nowadays, several microorganisms are used in the detoxification of these hazardous effluents. Researchers have found that microbial degradation is the most promising treatment method to remove high biological oxygen demand (BOD) and chemical oxygen demand (COD) from wastewater. Microorganisms also remove AOX toxicity, chlorinated compounds, suspended solids, color, lignin, derivatives, etc. from the pulp and paper mill effluents. But in the current scenario, mill effluents are known to deteriorate the environment and therefore it is highly desirable to deploy advanced technologies for effluent treatment. This review summarizes the eco-friendly advanced treatment technologies for effluents generated from pulp and paper mills.

Challenges in developing strategies for the valorization of lignin-a major pollutant of the paper mill industry

Apart from protecting the environment from undesired waste impacts, wastewater treatment is a crucial platform for recovery. The exploitation of suitable technology to transform the wastes from pulp and paper industries (PPI) to value-added products is vital from an environmental and socio-economic point of view that will impact everyday life. As the volume and complexity of wastewater increase in a rapidly urbanizing world, the challenge of maintaining efficient wastewater treatment in a cost-effective and environmentally friendly manner must be met. In addition to producing treated water, the wastewater treatment plant (WWTP) has a large amount of paper mill sludge (PMS) daily. Sludge management and disposal are significant problems associated with wastewater treatment plants. Applying the biorefinery concept is necessary for PPI from an environmental point of view and because of the piles of valuables contained therein in the form of waste. This will provide a renewable source for producing valuables and bio-energy and aid in making the overall process more economical and environmentally sustainable. Therefore, it is compulsory to continue inquiry on different applications of wastes, with proper justification of the environmental and economic factors. This review discusses current trends and challenges in wastewater management and the bio-valorization of paper mills. Lignin has been highlighted as a critical component for generating valuables, and its recovery prospects from solid and liquid PPI waste have been suggested.

Ionic liquid/TiO2 nanoparticles doped with non-expensive metals: new active catalyst for phenol photodegradation

TiO₂ nanoparticles were synthesized using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF₄) ionic liquid and doped with non-expensive metals Cu²⁺ and Fe³⁺ by the sol–gel method. The new generated photocatalysts had their morphological, textural and structural characteristics analysed by scanning electron microscopy and dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The results showed two phases by XRD analysis, anatase (majority) and rutile (minority). The SEM micrographs exposed spherical TiO₂ NPs/BMI·BF₄ IL and compact layers for Cu²⁺ and Fe³⁺-doped TiO₂ NPs in BMI·BF₄ IL, the EDX confirmed only the presence of Ti, O, Fe and Cu. The BET and BJH analyses exhibited high porous TiO₂ NPs/BMI·BF₄ IL. The BET and BJH analyses confirmed that the pore diameter of mesoporous materials was between 12 and 16 nm with similar values for surface area (55–63 m² g⁻¹). The TEM images exhibited spherical shape nanoparticles with mean diameter of 20–22 nm. The DRS analysis and Tauc equation were applied to estimate the optical energy band gap of the photocatalysts. The energy band gap values of 3.1 eV, 3.32 eV, and 2.78 eV were obtained for TiO₂ NPs/BMI·BF₄ IL, 1% Fe³⁺-doped TiO₂ NPs/BMI·BF₄ IL and 1% Cu²⁺-doped TiO₂ NPs/BMI·BF₄ IL, respectively. Phenol photodegradation was realized using Cu²⁺ and Fe³⁺-doped TiO₂ NPs/BMI·BF₄ IL under UV/visible irradiation and quantified by HPLC-FLD. The phenol photodegradation was investigated by different concentrations of metal-doped TiO₂ NPs/BMI·BF₄ IL. The new active photocatalysts 1% Cu²⁺-doped TiO₂ NPs and 1% Fe³⁺-doped TiO₂ NPs/BMI·BF₄ IL exhibited high catalytic activity (99.9% and 96.8%, respectively). The photocatalysts 1% Cu²⁺ and 1% Fe³⁺-doped TiO₂ NPs/BMI·BF₄ IL were also evaluated using industrial wastewater from the tobacco industry. The results showed 56.7% phenol photodegradation, due to the complexity of the tobacco matrix wastewater.

TiO₂ nanoparticles were synthesized using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF₄) ionic liquid and doped with non-expensive metals Cu²⁺ and Fe³⁺ by the sol–gel method.

Comparison of poly ferric chloride and poly titanium tetrachloride in coagulation and flocculation process for paper and cardboard wastewater treatment

The current study investigated the efficiency of poly ferric chloride (PFC) and poly titanium tetrachloride (PTC) in coagulation-flocculation process for treatment of paper and cardboard wastewater. The effect of pH (5-11), coagulant concentrations (100-1000 mg/L), mixing rate (10-60 rpm), mixing time (5-25 min), and settling time (5-30 min) were examined. The results showed that the removal efficiency for turbidity, total suspended solids (TSS), and chemical oxygen demand (COD) by PFC and PTC coagulants increased with pH rising up to 9 for the former and 7 for the latter coagulant. Furthermore, the removal efficiency for the afore-mentioned parameters increased along with a 30 rpm increase in the mixing rate, while the mixing time reached 20 min. It was also found that the best removal efficiencies for turbidity, TSS, and COD by PFC under optimal conditions (pH 9, coagulant dose 800 mg/L, and settling time of 25 min) were 97.11%, 99.1%, and 84.91%, respectively. In addition, the removal efficiencies for PTC (optimal conditions of pH 7, coagulant dose 600 mg/L, and settling time of 15 min) were found to be 98.29%, 99.29%, and 86.42%, respectively. Water recovery and the produced sludge volume by PFC were 80% and 200 cm³, respectively, in the settling time of 25 min and for PTC were 81.5% and 185 cm³, respectively, in the settling time of 15 min. Costs of the coagulation-flocculation process for treatment 1 m³ of paper and cardboard wastewater using PTC and PFC were 0.42 $ and 0.32 $, respectively. Finally, it can be concluded that compared to PFC, PTC with higher settling rate has a greater efficiency for treatment of paper and cardboard wastewater.

Robotics for enzyme technology: innovations and technological perspectives

The use of robotics in the life science sector has created a considerable and significant impact on a wide range of research areas, including enzyme technology due to their immense applications in enzyme and microbial engineering as an indispensable tool in high-throughput screening applications. Scientists are experiencing the advanced applications of various biological robots (nanobots), fabricated based on bottom-up or top-down approaches for making nanotechnology scaffolds. Nanobots and enzyme-powered nanomotors are particularly attractive because they are self-propelled vehicles, which consume biocompatible fuels. These smart nanostructures are widely used as drug delivery systems for the efficient treatment of various diseases. This review gives insights into the escalating necessity of robotics and nanobots and their ever-widening applications in enzyme technology, including biofuel production and biomedical applications. It also offers brief insights into high-throughput robotic platforms that are currently being used in enzyme screening applications for monitoring and control of microbial growth conditions. KEY POINTS: • Robotics and their applications in biotechnology are highlighted. • Robotics for high-throughput enzyme screening and microbial engineering are described. • Nanobots and enzyme-powered nanomotors as controllable drug delivery systems are reviewed.

Synthetic Organic Compounds From Paper Industry Wastes: Integrated Biotechnological Interventions

Synthetic organic compounds (SOCs) are reported as xenobiotics compounds contaminating the environment from various sources including waste from the pulp and paper industries: Since the demand and production of paper is growing increasingly, the release of paper and pulp industrial waste consisting of SOCs is also increasing the SOCs' pollution in natural reservoirs to create environmental pollution. In pulp and paper industries, the SOCs viz. phenol compounds, furans, dioxins, benzene compounds etc. are produced during bleaching phase of pulp treatment and they are principal components of industrial discharge. This review gives an overview of various biotechnological interventions for paper mill waste effluent management and elimination strategies. Further, the review also gives the insight overview of various ways to restrict SOCs release in natural reservoirs, its limitations and integrated approaches for SOCs bioremediation using engineered microbial approaches. Furthermore, it gives a brief overview of the sustainable remediation of SOCs via genetically modified biological agents, including bioengineering system innovation at industry level before waste discharge.

Microbial Nanotechnology for Bioremediation of Industrial Wastewater

Pollutant removal from industrial effluents is a big challenge for industries. These pollutants pose a great risk to the environment. Nanotechnology can reduce the expenditure made by industries to mitigate these pollutants through the production of eco-friendly nanomaterials. Nanomaterials are gaining attention due to their enhanced physical, chemical, and mechanical properties. Using microorganisms in the production of nanoparticles provides an even greater boost to green biotechnology as an emerging field of nanotechnology for sustainable production and cost reduction. In this mini review, efforts are made to discuss the various aspects of industrial effluent bioremediation through microbial nanotechnology integration. The use of enzymes with nanotechnology has produced higher activity and reusability of enzymes. This mini review also provides an insight into the advantages of the use of nanotechnology as compared to conventional practices in these areas.