A novel use of Moringa oleifera seed powder in enhancing the primary treatment of paper mill effluent

Research on Moringa (Moringa oleifera Lam.) in Africa

While Moringa oleifera Lam. is gaining importance in Africa, especially sub-Saharan Africa, it is unclear whether research is following the quick pace of its development on the continent. Therefore, this article analyzes the landscape of research dealing with moringa in Africa. This systematic review draws upon 299 eligible articles identified through a search carried out on the Web of Science in April 2023. Research on M. oleifera is rather recent in Africa but interest is increasing among scholars. While the research field is multidisciplinary and cross-sectoral, the literature seems to focus on biological and environmental sciences. Moreover, research is performed mainly in South Africa, Nigeria, Egypt, and Ghana. The analysis suggests a significant potential contribution of moringa to food security and nutrition, climate change mitigation/adaptation, farming systems resilience, and livelihoods. Its versatility and diverse applications and uses make moringa particularly interesting for developing countries, such as African ones. However, this review also underscores some factors hindering its development. Therefore, there is a need to strengthen research on moringa to unlock its potential in Africa. Investments in research, innovation, and development can help address the many challenges that Africa faces and contribute to the transition towards sustainable and resilient food systems.

An environmentally friendly approach for industrial wastewater treatment and bio-adsorption of heavy metals using Pistacia soft shell (PSS) through flocculation-adsorption process

In this research, the potential application of Pistacia soft shell (PSS) was investigated as a novel bio-based flocculant for pulp and paper wastewater (PPWW) treatment. In line with this, after characterization of the PSS, the removal efficiencies of chemical oxygen demand (COD), turbidity and heavy metals (Cu2+ and Pb2+) from PPWW were investigated with different dosage of PSS. The results were compared with alum as a reference flocculant. In addition, the effect of pH adjustment on the flocculation-adsorption performance of PSS was studied under acidic and alkaline condition. Zeta potential, BET, FTIR and SEM as well as kinetics and isotherm analyses were conducted for mechanistic understanding. According to the results, PSS treatment could remove COD, turbidity, Cu2+ and Pb2+ up to 67%, 87%, 70% and 74%, respectively which were better than alum: 56%, 85%, 31% and 35%. It was observed that, pH adjustment significantly improved the performance of PSS treatment. Maximum removal efficiencies of 92%, 95%, 97% and 98% were achieved for COD, turbidity, Cu2+ and Pb2+, respectively, under optimal condition of using 2 g/L PSS at pH 9. The mechanism analysis revealed that the high removal efficiency of PSS is related to the dual flocculation-adsorption of bridging and sweeping mechanisms. The results of this study suggested PSS as a promising, sustainable and eco-friendly bio-based flocculant and adsorbent for industrial wastewater treatment.

Electrochemical Characterization Using Biosensors with the Coagulant Moringa oleifera Seed Lectin (cMoL)

Triturated Moringa oleifera seeds have components that adsorb recalcitrant indigo carmine dye. Coagulating proteins known as lectins (carbohydrate-binding proteins) have already been purified from the powder of these seeds, in milligram amounts. The coagulant lectin from M. oleifera seeds (cMoL) was characterized by potentiometry and scanning electron microscopy (SEM) using MOFs, or metal-organic frameworks, of [Cu₃(BTC)₂(H₂O)₃]_n to immobilize cMoL and construct biosensors. The potentiometric biosensor revealed an increase in the electrochemical potential resulting from the Pt/MOF/cMoL interaction with different concentrations of galactose in the electrolytic medium. The developed aluminum batteries constructed with recycled cans degraded an indigo carmine dye solution; the oxide reduction reactions of the batteries generated Al(OH)₃, promoting dye electrocoagulation. Biosensors were used to investigate cMoL interactions with a specific galactose concentration and monitored residual dye. SEM revealed the components of the electrode assembly steps. Cyclic voltammetry showed differentiated redox peaks related to dye residue quantification by cMoL. Electrochemical systems were used to evaluate cMoL interactions with galactose ligands and efficiently degraded dye. Biosensors could be used for lectin characterization and monitoring dye residues in environmental effluents of the textile industry.

A comparative study on polyaluminum chloride (PACl) and Moringa oleifera (MO) chemically enhanced primary treatment (CEPT) in enhanced biogas production: anaerobic digestion performance and the Gompertz model

A comparative study was performed to estimate biogas production from sludge produced by organic and inorganic chemically enhanced primary treatments (CEPTs). To this end, the effects of two coagulants, polyaluminum chloride (PACl) and Moringa oleifera (MO), on CEPT and biogas production in anaerobic digestion were surveyed within an incubation period of 24 days. The optimal dosage and pH of PACl and MO were optimized in terms of sCOD, TSS and VS parameters in the CEPT process. Next, the digestion performance of anaerobic digestion reactors fed with sludge obtained from PACl and MO coagulants at a batch mesophilic reactor (37 ± 1 °C) was surveyed from the biogas production, volatile solid reduction (VSR) and Gompertz model. At the optimal conditions (pH = 7 and dosage = 5 mg L^-1), the removal efficiency of COD, TSS and VS in CEPT assisted with PACL was 63, 81 and 56%, respectively. Moreover, CEPT assisted with MO led to the removal efficiency of COD, TSS and VS until 55, 68 and 25%, respectively. The highest methane yield (0.598 L g_{VS removed}^-1) was obtained in an anaerobic digestion reactor with sludge from the MO coagulant. The anaerobic digestion of CEPT sludge instead of primary sludge resulted in higher sCOD removal efficiency, and 43-50% of sCOD was observed compared with the removal of 32% for the primary sludge. Furthermore, the high coefficient of determination (R²) demonstrated the trustworthy predictive precision of the modified Gompertz model with actual data. The combination of CEPT and anaerobic digestion, especially using natural coagulants, provides a cost-effective and practical way to increase BMP from primary sludge.

Combined organic coagulants and photocatalytic processes for winery wastewater treatment

Due to the consumers demand for quality wines, washing and disinfection operations are necessary in wine productions, leading to the generation of large volumes of winery wastewater (WW) with a high organic content which has the potential to cause irreversible environmental impacts. The aim and novelty of this work is the production of natural organic coagulants (NOCs) to be applied in coagulation-flocculation-decantation (CFD) process. To complement this treatment process, it is also aimed the performed a photo-Fenton process, combining hydrogen peroxide (H₂O₂) and potassium persulfate (KPS). The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) showed that NOCs are carbon-based materials with adsorption capacity. Under the best operational conditions, NOCs achieved a turbidity removal between 86.2 and 98.9%, a total suspended solids (TSS) removal ranging between 85.0 and 94.9% and a dissolved organic carbon (DOC) removal ranging between 14.1 and 44.9%. To degrade the DOC present in the WW, different advanced oxidation processes (AOPs) were tested. Results showed that KPS-photo-Fenton, under the best operational conditions [Fe²⁺] = 2.5 mM, [KPS] = 1.0 mM, pH = 3.0, radiation UV-C mercury lamp (254 nm), agitation 350 rpm, temperature 298 K, reaction time 240 min achieved a DOC removal of 91.2 and 96.8%, with a H₂O₂ consumption of 156.9 and 199.0 mM, respectively for red and white WW. With application of combined CFD-KPS-photo-Fenton process, it was observed an increase of DOC removal with lower H₂O₂ consumptions. The energy consumption of the photosystem was evaluated by application of electric energy per mass (E_EM). The application of KPS-photo-Fenton process achieved an E_EM of 0.308 and 0.0309 kWh/g/L DOC, with a cost of 2.05 and 2.59 €/g/L DOC respectively for red and white WW. The combination of CFD-KPS-photo-Fenton decreased significantly the costs of treatment and the treated wastewater achieved the Portuguese legal values for wastewater discharge. This work shows that NOCs are a promising technology that can be an alternative to traditional metal salts, the combination of sulfate radicals with hydroxyl radicals can achieve high DOC removal and the combination of CFD with KPS-photo-Fenton process can decrease the operational costs.

Textile Dye Removal by Acacia dealbata Link. Pollen Adsorption Combined with UV-A/NTA/Fenton Process

The decolourization of an aqueous solution of the textile dye Acid Red 88 (AR88) and the control of the invasive plant species Acacia dealbata Link. (ADL) were addressed in this work. The aims of the study were (1) characterization of the ADL pollen, (2) application of the pollen powder in adsorption processes, (3) selection of the best operational conditions for nitriloacetic acid (NTA)-UV-A-Fenton process and (4) assess the efficiency of the combined treatment adsorption and NTA-UV-A-Fenton in AR88 decolourization. In a first step, ADL pollen was used as a AR88 bioadsorbent. Fourier-transform infrared spectroscopy (FTIR) analysis were performed and revealed the presence of proteins, fatty acids, carbohydrates and lignin in the pollen. Afterwards, trough scanning electron microscopy (SEM), it was possible to verify that ADL pollen has several empty spaces that can be used for dye adsorption. Biosorption results showed higher adsorption of AR88 with application of pH 3.0 and [pollen] = 3.0 g/L with 18.8 mg/g of dye adsorbed. The best fitting was observed with Langmuir, SIPS and Jovanovic isotherms (0.993, 0.996 and 0.994, respectively). To complement the biosorption, a UV-A-Fenton process was applied, and results showed a higher AR88 removal with (NTA) addition. Higher irradiance power favored the oxidation process with high Ф photodegradation value and low Electric Energy per Order ($$E_{\text{EO}}$$ E EO ) and Specific Applied Energy ($$E_{\text{SAE}}$$ E SAE ). The combination of biosorption with NTA-UV-A-Fenton was the most efficient system with an AR88 decolourization of 98.5% and a total organic carbon (TOC) removal of 83.5%.

Graphical Abstract

Treatment of heavy metals containing wastewater using biodegradable adsorbents: A review of mechanism and future trends

The direct disposal of industrial effluents into the aquatic system is considered as a significant environmental hazard in many countries. Because of poisonous chemicals, substantial volumes of effluent release, as well as the lack of adequate of conventional treatment methodologies, industrial effluent treatment is extremely difficult. Numerous researchers have been interested in adsorption technology for its high efficiency of pollutant removal, low cost, and abundantly available adsorbent. Various adsorbent materials, both natural and modified form, have been widely used for the removal of toxic contaminants from industrial effluent. This paper highlights recent advancements in multiple modification types to functionalize the adsorbent material, resulting in higher adsorption capacity on various toxic pollutants. This review provides an overview of the adsorption mechanism and parameters (pH, adsorbent dosage, initial concentration, temperature and interaction time), which influencing the removal efficiency of adsorbents. Furthermore, this review compiles the desorption study to recover the adsorbent and improve the cycle's financial viability. This review provides a concise overview of the future directions and outlook in the framework of adsorbent application for industrial wastewater treatment.

Food By-Product Valorization by Using Plant-Based Coagulants Combined with AOPs for Agro-Industrial Wastewater Treatment

Re-using and adding value to by-products is one of the current focuses of the agri-food industry, following the Sustainable Development Goals of United Nations. In this work, the by-products of four plants, namely chestnut burr, acorn peel, olive leaf, and grape stem were used as coagulants to treat elderberry wastewater (EW), a problematic liquid effluent. EW pre-treatment using these natural coagulants showed promising results after pH and coagulant dosage optimization. However, the decrease in total organic carbon (TOC) was not significant, due to the addition of the plant-based natural coagulants which contain carbon content. After this pre-treatment, the photo-Fenton advanced oxidation process was selected, after preliminary assays, to improve the global performance of the EW treatment. Photo-Fenton was also optimized for the parameters of pH, H₂O₂, Fe²⁺, and irradiance power, and the best conditions were applied to the EW treatment. Under the best operational conditions defined in the parametric study, the combined results of coagulation–flocculation–decantation (CFD) and photo-Fenton for chestnut burr, acorn peel, olive leaf, and grape stem were, respectively, 90.2, 89.5, 91.5, and 88.7% for TOC removal; 88.7, 82.0, 90.2 and 93.1%, respectively, for turbidity removal; and finally, 40.6, 42.2, 45.3, and 39.1%, respectively, for TSS removal. As a final remark, it is possible to suggest that plant-based coagulants, combined with photo-Fenton, can be a promising strategy for EW treatment that simultaneously enables valorization by adding value back to food by-products.

Application of Natural Coagulants for Pharmaceutical Removal from Water and Wastewater: A Review

Pharmaceutical contamination threatens both humans and the environment, and several technologies have been adapted for the removal of pharmaceuticals. The coagulation-flocculation process demonstrates a feasible solution for pharmaceutical removal. However, the chemical coagulation process has its drawbacks, such as excessive and toxic sludge production and high production cost. To overcome these shortcomings, the feasibility of natural-based coagulants, due to their biodegradability, safety, and availability, has been investigated by several researchers. This review presented the recent advances of using natural coagulants for pharmaceutical compound removal from aqueous solutions. The main mechanisms of natural coagulants for pharmaceutical removal from water and wastewater are charge neutralization and polymer bridges. Natural coagulants extracted from plants are more commonly investigated than those extracted from animals due to their affordability. Natural coagulants are competitive in terms of their performance and environmental sustainability. Developing a reliable extraction method is required, and therefore further investigation is essential to obtain a complete insight regarding the performance and the effect of environmental factors during pharmaceutical removal by natural coagulants. Finally, the indirect application of natural coagulants is an essential step for implementing green water and wastewater treatment technologies.

Integration of coagulation-flocculation and heterogeneous photocatalysis for the treatment of pulp and paper mill effluent

A two-step process involving coagulation-flocculation followed by solar photocatalysis - based Advanced Oxidation Process (AOP) using TiO₂-Reduced Graphene Oxide (TRGO) nanocomposite as catalyst has been employed for the treatment of pulp and paper mill effluent. As the effluent is loaded with a high amount of organics with initial chemical oxygen demand (COD) as high as 3516, a pre-treatment is required before applying photocatalytic treatment. Coagulation-flocculation was identified as an effective pre-treatment strategy. Among the various coagulants tested, CuSO₄.5H₂O showed the best % COD reduction of 84 at pH 6, at a loading of 5 g/L. The primary treatment of coagulation improved the biodegradability index from 0.23 to 0.37. TRGO photocatalyst, employed in the second stage of photocatalytic treatment was synthesised by an ultrasound assisted solvothermal method and well characterised by various spectroscopic/analytical tools. The composite was found to be an efficient solar photocatalyst and achieved 1.76 and 2.1 times more COD reduction than synthesised TiO₂ and commercial P25 respectively. The final effluent after the combined treatment was neutral and the biochemical oxygen demand (BOD) and COD were 11.7 and 120 mg/L respectively which were below the given limit of National Environmental Quality Standards.

Treatment of cosmetic industry wastewater by flotation with Moringa oleifera Lam. and aluminum sulfate and toxicity assessment of the treated wastewater

The production of personal hygiene and body products generates wastewater with a high load of surfactants, a high chemical oxygen demand (COD), and abundant oils and greases. Aluminum sulfate (AS) and two solutions of natural coagulant from Moringa oleifera Lam. seeds prepared with a 1M NaCl solution and 1.5M NaCl solution were used. Aluminum sulfate, Moringa oleifera Lam. in 1M NaCl, and Moringa oleifera Lam. in 1.5M NaCl solutions reduced turbidity at rates 94.48%, 98.07%, and 97.87%; reduced COD at rates 46.36%, 49.15%, and 42.7%; and reduced oil and grease at rates 98.72%, 78.65%, and 97.41%, respectively. Mutagenicity tests with guppies showed a lower toxicity of Moringa oleifera Lam. extract compared with aluminum sulfate. This work shows that Moringa oleifera Lam. extract has high potential for use as an alternative to aluminum sulfate; therefore, this study will contribute to proposals for the sustainable treatment of effluents from the cosmetic industry.

Starch engineered with Moringa oleifera seeds protein crosslinked Fe3O4: A synthesis and flocculation studies

This study aimed to utilize cationic protein extracted from the Moringa oleifera seed in the fabrication of cationic starch crosslinked with magnetic nanoparticles (MagCS). Important synthesis parameters include starch to cationic protein volume ratio, magnetic nanoparticles mass fraction, reaction and crosslinking time, reaction and crosslinking temperature and crosslinker concentration. At optimum synthesis conditions, MagCS yield a 38.55% amide content, 2.46 degree of substitution, 1.1 mmol/g charge density and 78.6% crosslinking, which are much higher compared to other starch derivatives. A series of characterization analyses such as Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, elemental analysis and vibrating sample magnetometer concluded that MagCS was embedded with amide group, has high crystallinity structure, is thermally stable and shows a promising magnetic characteristic. Based on the synthesis parameters and characterization studies, the synthesis mechanism of MagCS was also postulated. The flocculation performance of MagCS was successfully assessed for the treatment of palm oil mill effluent. At optimum dosage, initial pH and settling time of 1.0 g/L, 9.0 and 15 min, the MagCS flocculant was able to remove 90.48, 83.95 and 58.19% of turbidity, color and chemical oxygen demand, respectively. This study provides an alternative eco-friendly materials in the wastewater treatment application.

Moringa oleifera seed defatted press cake based biocoagulant for the treatment of coal beneficiation plant effluent

This study proposes a unique way of preparation of biocoagulant from Moringa oleifera defatted seed press cake. The press cake used in this study is a waste material produced as a by-product during cold press oil making from Moring oleifera seeds. The prepared Moringa oleifera seed defatted press cake based biocoagulant was found more effective than presently used metallic and polymer-based coagulants and flocculants for removal of fine particles of colloidal size from the effluent generated in the process of coal beneficiation. The detailed characterization of Moringa oleifera defatted seed press cake and the prepared biocoagulant for Particle size, Field Emission Scanning Electron Microscopy, Energy Dispersive X-Ray analysis, Zeta Potential, Fourier-transform Infrared Spectroscopy, etc. was done. The biocoagulant has been found effective in 97.4% total suspended solids removal and 97.48% turbidity removal from coal beneficiation plant effluent. The biocoagulant has been found to work satisfactorily under high fluxes of turbidity and total suspended solids with high removal of fine particles. The age of biocoagulant had negligible effect on fine particle removal efficiency (97.4% for fresh to 95% for 3-week-old biocoagulant). Field Emission Scanning Electron Microscopy analysis reveals considerable increase in flocs size from 198 nm to a 20 μ size well-developed flocs. The biocoagulant has proved as an efficient substitute of the metallic and polymer-based coagulants for the efficient treatment of coal beneficiation plant effluent.

Moringa oleifera seeds-removed ripened pods as alternative for papersheet production: antimicrobial activity and their phytoconstituents profile using HPLC

In the present study, and for the waste valorization, Moringa oleifera seeds-removed ripened pods (SRRP) were used for papersheet production and for the extraction of bioactive compounds. Fibers were characterized by SEM–EDX patterns, while the phytoconstituents in ethanol extract was analyzed by HPLC. The inhibition percentage of fungal mycelial growth (IFMG) of the treated Melia azedarach wood with M. oleifera SRRP extract at the concentrations of 10,000, 20,000, and 30,000 µg/mL against the growth of Rhizoctonia solani and Fusarium culmorum was calculated and compared with fluconazole (25 µg). The produced papersheet was treated with the ethanol extract (4000, 2000, and 1000 µg/mL) and assayed for its antibacterial activity against Agrobacterium tumefaciens, Erwinia amylovora, and Pectobacterium atrosepticum by measuring the inhibition zones and minimum inhibitory concentrations (MICs). According to chemical analysis of M. oleifera SRRP, benzene:alcohol extractives, holocellulose, lignin, and ash contents were 7.56, 64.94, 25.66 and 1.53%, respectively, while for the produced unbleached pulp, the screen pulp yield and the Kappa number were 39% and 25, respectively. The produced papersheet showed tensile index, tear index, burst index, and double fold number values of 58.8 N m/g, 3.38 mN m²/g, 3.86 kPa m²/g, and 10.66, respectively. SEM examination showed that the average fiber diameter was 16.39 µm, and the mass average of for elemental composition of C and O by EDX were, 44.21%, and 55.79%, respectively. The main phytoconstituents in the extract (mg/100 g extract) by HPLC were vanillic acid (5053.49), benzoic acid (262.98), naringenin (133.02), chlorogenic acid (66.16), and myricetin (56.27). After 14 days of incubation, M. oleifera SRRP extract-wood treated showed good IFMG against R. solani (36.88%) and F. culmorum (51.66%) compared to fluconazole, where it observed 42.96% and 53.70%, respectively. Moderate to significant antibacterial activity was found, where the minimum inhibitory concentration (MIC) values were 500, 650, and 250 µg/mL against the growth of A. tumefaciens, E. amylovora, and P. atrosepticum respectively, which were lower than the positive control used (Tobramycin 10 µg/disc). In conclusion, M. oleifera SRRP showed promising properties as a raw material for pulp and paper production as well as for the extraction of bioactive compounds.

Influence of bionanoparticles to treat a slaughterhouse wastewater

Treatment of effluents from animal slaughterhouse industries is indispensable, standing out coagulation/flocculation/sedimentation processes. Bionanoparticles (BioNPs) (nanoparticles (NPs) functionalized with Moringa extracts (MO)) were studied as an alternative natural coagulant that would contribute to the microbial load reduction, without increasing the treated effluent toxicity. MO extracts were prepared with different salts, and then, in a kinetics study, different NPs mass and coagulant dosages were evaluated. In the best-defined conditions, microbial load, toxicity tests for the bioindicator Lactuca sativa, and NPs reuse evaluation were performed. Removals of 96.14% turbidity and 43.63% UV254nm were achieved when using 500 mg L-1 of BioNPs containing 60 mg of NPs for every 20 mL of MO extract prepared with 0.1 M CaCl2. The BioNPs with an external magnetic field also decreased the sedimentation time from 140 to 10 min compared to MO, and the process efficiency did not expressively decrease after reusing the recovered NPs. Through toxicity tests, BioNPs were not considered to leave residuals toxic to the Lactuca sativa in the treated effluent. Besides, the microbial load reduction was 97.33% for heterotrophic microorganisms and total mesophiles and 99.25% for moulds/yeasts. Therefore, a satisfactory primary treatment was achieved, contributing to the sustainability of industries.

Kinetic and Prediction Modeling Studies of Organic Pollutants Removal from Municipal Wastewater using Moringa oleifera Biomass as a Coagulant

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of 50, 100, 150, 200 mg/L, and a control (0 mg/L) treatment were performed for a settling period of 250 min at room temperature. Kinetics and prediction variables of cumulative turbidity, BOD, and COD removal were estimated using simplified first order and modified Gompertz models. Results showed that the maximum removal of turbidity, BOD, and COD were 94.44%, 68.72%, and 57.61%, respectively, using an MO dose of 150 mg/L. Various kinetic parameters, such as rate constant (r), measured (REm) versus predicted (REp) cumulative removal, and specific pollutant removal rate (µm), were also maximum when an MO dose of 150 mg/L was added, the standard error being below 5%. The developed models were successfully validated over multiple observations. This study suggests low cost and sustainable removal of turbidity, BOD, and COD of municipal wastewater using MO seed biomass as a coagulant.

Coagulation of Metallic Pollutants from Wastewater Using a Variety of Coagulants Based on Metal Binding Interaction Studies

In this study, different organic (moringa and neem leaf powder) and inorganic (alum) coagulants were used for the wastewater treatment. Results revealed that all the coagulants at various doses significantly affected the pH, electrical conductivity (EC) and turbidity of wastewater. The maximum decrease in all the attributes was observed when 10 g of coagulants were used. Similarly, maximum adsorption potential was observed in case of moringa leaf powder. Maximum decrease in all physiochemical attributes such as pH (13%), EC (65%), turbidity (75%), total dissolved solids (TDS; 51%), total suspended solids (TSS; 48%), total hardness (TH; 29%), chloride contents (66%) and phosphate contents (44%) was observed. Regarding the heavy metals, maximum decrease for Cadmium (Cd; 96%), Lead (Pb; 88%), Arsenic (As; 23%), Iron (Fe; 90%), Manganese (Mn; 96%) and Zinc (Zn; 48%) was observed in same treatment. The decreasing order in terms of their adsorption potential for coagulants was moringa leaf powder > Alum > neem leaf powder. However, the maximum effect of coagulants was observed in case of textile wastewater as compared to the hospital wastewater. Based on the analyses, it is concluded that the moringa leaf powder has maximum adsorption potential for the remediation of wastewater.

Application progress of enhanced coagulation in water treatment

Water industries worldwide consider coagulation/flocculation to be one of the major treatment methods for improving the overall efficiency and cost effectiveness of water and wastewater treatment. Enhancing the coagulation process is currently a popular research topic. In this review article, the latest developments in enhanced coagulation are summarized. In addition, the mechanisms of enhanced coagulation and the effect of process parameters on processing efficiency are discussed from the perspective of ballast-enhanced coagulation, preoxidation, ultrasound, and composite coagulants. Finally, improvements and new directions for enhanced coagulation are proposed.

This review summarizes the current situation of enhanced coagulation and looks forward to future development.

Removal efficiency of Gram-positive and Gram-negative bacteria using a natural coagulant during coagulation, flocculation, and sedimentation processes

Staphylococcus sp. as Gram-positive and Escherichia coli as Gram-negative are bacterial pathogens and can cause primary bloodstream infections and food poisoning. Coagulation, flocculation, and sedimentation processes could be a reliable treatment for bacterial removal because suspended, colloidal, and soluble particles can be removed. Chemical coagulants, such as alum, are commonly used. However, these chemical coagulants are not environmentally friendly. This present study evaluated the effectiveness of coagulation, flocculation, and sedimentation processes for removing Staphylococcus sp. and E. coli using diatomite with standard jar test equipment at different pH values. Staphylococcus sp. demonstrated 85.61% and 77.23% significant removal in diatomite and alum, respectively, at pH 5. At pH 7, the removal efficiency decreased to 79.41% and 64.13% for Staphylococcus sp. and E. coli, respectively. At pH 9, there was a decrease in Staphylococcus sp. after adding diatomite or alum compared with that of E. coli. The different removal efficiencies of the Gram-positive and Gram-negative bacteria could be owing to the membrane composition and different structures in the bacteria. This study indicates that diatomite has higher efficiency in removing bacteria at pH 5 and can be considered as a potential coagulant to replace alum for removing bacteria by the coagulation process.

Pulp and paper mill effluent management

This is a review of the literature published in 2018 related to the prevention of water pollution by or recovery of beneficial materials from wastewater produced in the pulp and paper industry. This review includes the following main sections: cleaner production, biological treatment, and physico-chemical treatment. PRACTITIONER POINTS: Converting pulp and paper treatment sludges to value-added materials can be efficient cleaner production technique. Modeling and dynamic simulation techniques of biological treatment along with optimization methods can improve the effluent quality out of a paper mill. Hybrid treatment systems can have a synergistic effect on the treatment of pulp and paper effluents.

Highly efficient removal of surfactant from industrial effluents using flaxseed mucilage in coagulation/photo-Fenton oxidation process

In this study, flaxseed mucilage (FSM) has been used as a green coagulant in the pretreatment stage of a combined process for the removal of an anionic surfactant, sodium dodecyl sulfate (SDS). In the post-treatment stage, heterogeneous photo-Fenton-like oxidation using MnFe₂O₄ nanocatalyst was applied to remove the remained SDS. Using response surface methodological approach, optimum condition in the coagulation process was obtained at pH 7.0, FSM dose of 100 mg L^-1 and 30 min. In the photo-Fenton oxidation process, complete SDS removal was achieved using 76 mg of the nanocatalyst, 1.07 mL of H₂O₂ at 17 min. Application of the combined process on the real wastewater samples indicates that the proposed method can be used effectively for the treatment of industrial effluents containing surfactants.