Turbidity Removal Efficiency Research Articles

Prolonged stirring pelleting coagulation for the enhanced treatment of fresh leachate: Removal performance and floc characteristics

Conventional coagulation (CC) is a widely adopted method for the pre-treatment of fresh leachate for enhancing subsequent advanced treatment processes. However, the formation of fluffy flocs in the CC process often results in limited separation and removal efficiency. In this study, a continuous alkali dosing prolonged stirring pelleting coagulation (C-PPC) process was proposed for the pre-treatment of fresh leachate. The C-PPC process consisted of three stages: prolonged stirring, reaction, and pelleting, achieving higher suspended solid (SS), turbidity, and organic removal efficiency compared with both CC and PPC processes. At a prolonged stirring intensity of 1500 r/min (G = 4241 s−1) and a final pH of 12, with polyaluminum chloride (PAC) and polyacrylamide (PAM) dosages of 2000 mg/L and 25 mg/L, impressive removal efficiency of 93.7 % SS, 99.7 % turbidity, and 35.7 % organic were obtained. In the prolonged stirring stage, the primary particle size decreased from 16.848 μm to 6.755 μm due to intensive stirring for 30 min, facilitating the compact floc formation. In the subsequent reaction stage, PAC was dosed once while NaOH was continuously dosed to achieve a final pH of 12 within 10 min. The floc size initially decreased due to fragmentation and small metal crystal generation. Subsequently, the generated small metal crystals served as the nuclei for organic matter adsorption and were entrapped by generated flocs, resulting in a significant increase in floc size with higher sphericity. Furthermore, compact pellets were formed during the pelleting stage after the addition of PAM. Floc restructuring also occurred during the pelleting stage, leading to a decreased pore volume of mesopores, achieving final floc densification and superior separation performance.

Development of low-pressure polymeric membrane incorporated with powdered activated carbon and nanosilica for groundwater applications

Groundwater has become a vital alternate supply of freshwater, which has now frequently been contaminated with high iron and lead levels that are harmful to human health and agriculture. Hence, various modifications on membrane surfaces are fabricated in this study to improve the membrane’s performance. Low-pressure PES polymeric membranes are made by combining polyether sulfone (PES) as the polymer, N-methyl-2- pyrrolidone (NMP) as the solvent, and nano-silica (SiO2) and powdered activated carbon (PAC) as additives. The membranes’ performance is tested multiple times to evaluate for their pure water permeation, groundwater filtration flux, the effectiveness of groundwater turbidity, colour, chemical oxygen demand (COD), iron, and lead removal. Results showed that the 5.0 wt.% PES-PAC membrane has the best filtering permeate and flux volume along with the highest removal efficiency for turbidity, colour, COD iron, and lead removal, which are 99.33%, 96.15 %, 96%, 100%, and 100%, respectively. All low-pressure membrane systems successfully reduced the iron concentration in groundwater to the irrigation water standards. Whereas, the 5.0 wt% PES-PAC and 5.0 wt% PES-SiO2 membranes can meet the lead requirements for agricultural water. The membrane with 5.0 wt% PES-PAC fulfils the lead content requirement after treatment for drinking water quality showing the membrane with PAC incorporation as an alternative water treatment technology to ensure water safety.

Optimization of Flotation Efficiency of Micro Bubbles Using Low-Energy Best Available Technique

Global warming caused by urbanization, industrialization, and population growth is leading to climate change and threatening our sustainable lives. As a response to this climate crisis, a best available technique(BAT) that minimizes the emission of existing pollutants and is also economical is required. The purpose of this study is to develop a lowenergy micro bubble generator to reduce energy consumption in water treatment facilities and to evaluate its performance in comparison with dissolved air flotation(DAF) and coagulation-flocculation processes. The low-energy micro bubble generator consists of an air injector, a chamber, and a nozzle. The experimental results showed that the low-energy micro bubble generator generated micro bubbles of similar size to DAF at an air injection rate of 5 ml/min. In addition, the flocculant concentration experiments showed that the low-energy micro bubble generator had 1.3-2.5 times higher turbidity removal efficiency than DAF and coagulation-flocculation processes even with flocculant injection of 8 mg/L or less. These results suggest that the low-energy micro bubble generator is effective in removing suspended solids from water and is an optimal solution for reducing carbon emissions. This study is expected to contribute to the increased utilization of this technology in industrial sites.

Development and evaluation of paddy straw and wheat chaff filter socks for sediment control in surface runoff

ABSTRACT Agricultural waste, often burned after harvest, poses significant environmental risks. This study explores the innovative use of these byproducts as biofilters for stormwater management. The study evaluated paddy straw and wheat chaff filter socks for removing suspended solids from canal water and stormwater runoff. Different sock sizes (15, 22.5, and 30 cm diameter) and densities were tested, each with a fixed length of 120 cm. They achieved up to 65% removal efficiency for suspended solids and turbidity while minimally impacting other water quality parameters. The filter sock’s life varied with inlet total suspended solids, lasting 44–56 hours for loads under 300 ppm and less than 14 hours for loads over 700 ppm. The study suggests using filter socks with a 30 cm diameter and medium to high density for optimal performance in reducing suspended solids. These filter socks offer a sustainable and eco-friendly solution for stormwater management, promoting resource conservation.

Coagulation-Flocculation/Pyrolysis Integrated System for Dye-Laden Wastewater Treatment: A Techno-Economic and Sustainable Approach

While several studies have employed coagulation-flocculation (CF) for textile wastewater (TW) treatment, conventional process optimization techniques cause insufficient pollution reduction and large sludge volume generation that deteriorate the environmental matrix and elevate the system’s operating cost. To avoid these drawbacks, this study focuses on optimizing an integrated CF/pyrolysis process using artificial intelligence technique and response surface methodology (RSM) for the dual benefit of TW treatment and biochar production. In the CF experiment, water hyacinth (WH) was employed as a bio-coagulant material for TW treatment under different pH, coagulant dosage, mixing speed, and settling time levels. Under the optimum CF conditions yielded by RSM and artificial neural network (ANN) models (initial pH: 5.5 vs. 5.7, WH dosage: 3.76 g/L vs. 3.5 g/L, settling time: 116 min vs. 102 min, and slow mixing speed: 25 rpm vs. 23 rpm), incomparable removal efficiencies for dye (87.3% vs. 91.3%) and turbidity (93.4% vs. 98.2%) were obtained. These removal efficiencies dropped to 83.5% and 87.6%, respectively, for operating the CF process using unoptimized operating factors. The pyrolysis of post-coagulation sludge yielded a carbon-rich biochar material characterized by a porous structure and abundant cationic microelements. The integrated performance of the CF/pyrolysis scheme under ANN-based optimal conditions achieved a shorter payback period of 5.2 years compared to RSM (5.7 years) and unoptimized (7.9 years) conditions. Furthermore, the optimized scheme supported several sustainable development goals that complied with clean water, good health, and climate change mitigation.Graphical

Evaluating the Separation Performance and Efficiency of MF Membranes in Industrial Textile Wastewater Treatment

The rapid growth of the population and industrial development have led to a significant increase in wastewater generation across various sectors. The textile industry stands out as a major contributor to economic growth but also a substantial source of environmental pollution. The typical effluents discharged from textile industries are a complex mixture of dyes, metals, and other pollutants. The presence of high levels of pollutants may overwhelm traditional treatment methods. Therefore, it is necessary to use more advanced techniques such as membrane filtration to treat the wastewater. Membrane technology has recently become famous for wastewater treatment due to its flexibility, high efficiency in removing contaminants, and low energy usage. There are several membrane filtration methods which are extensively used in water treatment procedures, including microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). In this study, the membrane process investigated the effect of feed pressure using a commercial MF flat sheet membrane on the performance of treatment. The pressure of the feed varies from 2 to 10 bar, with a stepwise increment of 2 bar. The water flux was measured using a cross-flow filtration system, and performance was assessed by calculating the water flux and removal efficiencies for total suspended solids (TSS) and turbidity. The results show that the MF membrane has a high removal efficiency of total suspended solids and turbidity. The removal efficiency of TSS ranged from 87.1% to 96.2%, while the removal efficiency of turbidity ranged from 91.2% to 93.7%.

Evaluation of plant-based coagulants for turbidity removal and coagulant dosage prediction using machine learning

ABSTRACT This study investigates the use of six plant-based coagulants – Acacia erioloba, Ricinodendron rautanenii, Schinziophyton rautanenii, Peltophorum africanum, Delonix regia, and Maerua angolensis for the removal of turbidity from wastewater effluent. The coagulants were characterized using Scanning Electron Microscopy (SEM) to determine morphological structure, X-ray fluorescence (XRF) to assess chemical composition, and X-ray diffraction to analyse the molecular structure. The coagulation process was evaluated using jar tests with varying coagulant dosages and pH levels. SEM images revealed irregular, rough surfaces, with all materials being amorphous and non-crystalline. Significant levels of essential elements, including iron (Fe), calcium (Ca), sulphur (S), and potassium (K) were revealed. Turbidity removal efficiency fluctuated with pH, showing optimal results under alkaline conditions. Notably, strong negative correlations between pH and turbidity were observed for all coagulants except Peltophorum africanum at a dosage of 20 g/L. Doubling the coagulant volume achieved turbidity reductions between 59% and 92.24%, except for Acacia erioloba and Ricinodendron rautanenii at a dosage of 40 g/L, which showed increased turbidity. The study also employed machine learning techniques to analyse the data and predict the most effective coagulant dosage under different pH conditions. These findings suggest that plant-based coagulants could be viable alternatives to chemical coagulants, with machine learning providing accurate predictions of coagulation performance. Further research is recommended to explore the capabilities of these natural coagulants fully.

Alkaline coagulation for separation of outdoor anaerobically cultured microalgae using natural-based coagulant

Although, native microalgae (MA) grows in alkaline environments, there is a lack of information from previous studies on the separation of microalgae culture under alkaline coagulation-flocculation-sedimentation (CFS) conditions. This study evaluated the separation efficiency of tannin (TA), Moringa oleifera seed extract (MOSE) natural coagulants in comparison with Aluminum sulfate (AS) for harvesting MA grown in anaerobically digested sanitary wastewater in a pilot flat panel photobioreactor in outdoor environment. The aim was to establish a pathway for recovery of microalgae biomass and supernatant without pH control and save cost for pH adjustment chemicals, in alignment with the circular economy concepts. Total suspended solids (TSS), turbidity and MA concentration (optical density – OD) were monitored throughout the tests. Optimum dosages of TA (1100 mg l−1), MOSE (3000 mg l−1) and AS (320 mg l−1) determined from jar tests were evaluated after MA cultivation, with natural pH of 10.4 under CFS condition (Coagulation: velocity gradient (Gf) of 200 s−1 for 2 min, flocculation: Gf of 10 s−1 for 15 min and sedimentation: 10 min observation time). TA and AS presented similar high removal efficiencies for turbidity (≥ 95 %), OD (≥ 87 %) and TSS (≥ 62 %). However, TA recorded a good pH (7.6) for the supernatant compared to an unsatisfactorily low 5.2 for AS. TA presented the potential of harvesting MA biomass without prior pH control and without adversely impacting the medium's pH. This shows that biomass has a potential usage as a biofertiliser and as well the resultant supernatant is reusable for non-potable purposes.

The effectiveness of ozonation treatment in reducing ph, turbidity, bod, cod, and toc in pharmaceutical industrial wastewater

Abstract The pharmaceutical industry’s fabrication of pharmaceutical products releases byproducts that have the potential to negatively impact the environment. Indicators of contaminants include characteristics such as COD, BOD, TOC, pH, and turbidity that are within acceptable standards of excellence. The objective of this study was to look at fluctuations in the concentrations of pharmaceutical wastewater substances parameters before and following treatment with the ozonation method, as well as to assess the ozonation procedure’s performance on pharmaceutical wastewater contaminants parameters. The ozonation methods, which altered the O3 retention period, served as the independent variable in this study. The dependent variables applied were pH optimalization, and the removal efficiency of turbidity, BOD, COD, and TOC. Controlling variables involve the starting pollutant concentration, pressure and temperature levels, and equipment conditions. To determine the ideal time variation for the ozonation process, many variations will be evaluated. However, several parameters (e.g. pH, BOD, and TOC) were not reducing with the designed time variations. Nevertheless, this approach was effective in reducing turbidity levels by 48.5% and COD levels by 55.4% over 15 minutes.

Novel cationic and amphoteric starch-modified coagulants for efficient treatment of relatively high turbidity and large organic matter source waters: Performance, predictive modeling and mechanism analysis

Finding alternative solutions of water source containing short-term relative high turbidity and large organic content is a pressing need in view of the inherent limitations of traditional inorganic coagulants. Requirement of significant dosage increase for conventional iron and aluminum salt coagulants can create several challenges including dose adjustment, suboptimal performance and high concentration of residual metal ions. In this study, acrylamide monomer (AM) and methacryloyloxyethyltrimethylammonium chloride (DMC) were grafted onto starch and carboxymethyl starch to obtain novel cationic and amphoteric starch-modified coagulants. Concurrently, the obtained coagulants were comprehensively evaluated under varying simulated water quality conditions to analyze their turbidity and organic matter removal efficiencies. Polymerized aluminium chloride (PACl) was used as the reference coagulant to evaluate the roles of polymer charge density, total charge, and molecular chain length in the coagulation mechanism for further illustration of their efficacy. In comparison to the traditional coagulant PACl, the modified coagulant was found to be more effective in enhancing flocculation and aggregation behavior, lowering of energy barriers, and enhancing adsorption energy by using the Density Functional Theory (DFT) calculations and Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory based investigation of the mechanism. Moreover, these behaviors were mainly attributed to significant exchange of charge density between coagulant and the pollutants. Additionally, in order to facilitate accurate and efficient treatment of water having diverse qualities, quadratic polynomial equation based mathematical model was constructed for quantitative analysis and model prediction. Findings of this study point towards an effective and precise approach to coagulation technology and thereby enabling sustainable and efficient purification of turbid source water containing large organic matter.

Mechanism and effect of magnetic biochar on the removal of norfloxacin from water by ozone peroxidation adsorption-coagulation process

Norfloxacin (NOR) is a widely used antibiotic, and its persistent residues in water have become a significant environmental concern. Due to its high concentration and persistence, NOR poses a threat to both the ecological environment and human health. Therefore, the development of effective water treatment technologies for removing NOR from water has become a critical issue. This study developed a novel adsorbent and integrated it with an ozone pre-oxidation-adsorption coagulation process to enhance the removal efficiency of NOR from turbid water. Adsorption experiments were conducted to investigate the effects of various conditions on the removal efficiency of NOR and to explore the underlying removal mechanisms. Additionally, the process parameters in the ozone pre-oxidation-mechanical stirring-clarifier sedimentation system were optimized. The results indicate that when the adsorbent dosage is 1 g/L and the pH is 7, the removal efficiency of NOR reaches 92.1 %. The primary adsorption mechanisms involved include hydrogen bonding, cation exchange, electrostatic attraction, intercalation, π-π interactions, and oxidation. Additionally, under conditions of 1 g/L adsorbent dosage, a 60-min reaction time, 20 mg/L PAC dosage, and a 0.1 m3/h ozone flow rate, the removal efficiencies of NOR and turbidity were 88.69 % and 81.55 %, respectively. In conclusion, the combination of ozone pre-oxidation and adsorption-coagulation technology proves to be an effective method for treating high-concentration antibiotic wastewater.

Treatment of molasses-based alcohol distillery wastewater using Electro-Fenton oxidation: Optimization and model prediction by response surface methodology

In this study, an Electro-Fenton process was employed to treat high-strength alcohol distillery wastewater. The simultaneously removal of chemical oxygen demand (COD), color, and turbidity were examined. The optimum value of the operational parameters including the number of electrodes and their arrangement, electrodes’ interval, initial pH, and electrolyte concentration were determined by one-factor-at-a-time (OFAT). The effect of essential parameters including current density, hydrogen peroxide concentration, and the duration of the process were optimized using response surface methodology (RSM). At fixed defined operational conditions by OFAT as four electrodes in a parallel arrangement with a 1 cm interval, 0.3 mol/L of electrolyte salt, and pH of 4, respectively, the optimal condition by RSM suggested the current density of 24 mA/cm2, 40 g/L of H2O2, and reaction time of 2 h. By adopting optimal condition at defined values of operational factors the removal efficiencies for COD, color, and turbidity were approximately 83%, 99%, and 97%, respectively, using fresh water for dilution. The energy consumption of 1.9 kWh/kg COD removal was achieved. Also, to save water, the treated wastewater (instead of fresh water) was used for the dilution of the raw wastewater, indicating the satisfactory results with removal efficiencies for COD, color, and turbidity of 71%, 94%, and 95%, respectively. Overall, the Electro-Fenton process is introduced as an appropriate process for treating high-strength alcohol distillery wastewater.

Using phragmites australis biochar bio-augmented with actinomycetes for enhancing UASB reactor performance: A field study

Anaerobic processes are a cost-effective and sustainable method for wastewater treatment due to their lower energy demand and potential for biogas-high methane recovery. The up-flow anaerobic sludge blanket reactor system (UASB) is a commonly used technology. This study aimed to evaluate the performance of UASB reactors for handling the wash water from the buffalo shed, with a comparison of traditional UASB to UASB modified reactor by incorporation of immobilized biochar with and without bioaugmentation of a bacterial species with documented anaerobic capabilities. The investigation was conducted as a pilot project at the Suez Canal University Veterinary Experimental Farm in Ismailia, Egypt. Adding Streptomyces hydrogenans S11-immobilized Phragmites australis biochar to the USAB reactor increased removal efficiency, even at high influent loadings. The findings demonstrated that the traditional UASB reactor attained removal efficiency for COD, BOD5, TSS, TDS, color, and turbidity of 81.0 %, 75.0 %,80.0 %, 80.0 %, 70.0 %, and 70.0 % respectively, and biogas production of (0.025 mL biogas/mg COD removed).In comparison, the modified UASB reactor attained COD, BOD5, TSS, TDS, Color, and Turbidity removal efficiencies of 93.0 %, 91.5 %,90.3 %, 91.10 %, 85 %, and 80.0 %, respectively. The biogas production reached (0.037 mL biogas/mg COD removed). The removal efficiencies of the measured parameters were statistically analyzed, and this analysis indicated that the efficiency of the modified reactor was enhanced dramatically compared to the traditional system. Hence, this work demonstrates an efficient approach for treating buffalo wastewater.

Slaughterhouse wastewater remediation using carbonized sawdust followed by textile filtration

Slaughterhouse wastewater (SWW) is considered an industrial wastewater, which seriously harms the environment due to the high concentration of contaminants such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS). Additionally, the wastewater from slaughterhouses contains harmful bacteria. This study used a lap-scale model to treat SWW from a local private slaughterhouse. The treatment process involves three stages: adsorption using activated carbon, which is derived from sawdust, followed by sedimentation, and finally, a slow sand filter with a modified layer of woven textile cotton. The first two steps were tested to obtain the ideal operation condition of the treatment system. After the final step of treatment, we evaluated the overall process using a modified slow sand filter (MSSF). We used a Jar test to determine the optimal dosage of activated carbon from sawdust (ACS). The monitored parameters were physicochemical, such as turbidity, total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), and total nitrogen (TN). The bacteriological examination included both total coliform count (TCC) and fecal coliform count (FCC). The results of the jar test revealed that the optimal ACS dose was 2.0 g/l. After adjusting the contact time and pH levels for the adsorption process, we discovered that the ideal contact time was 100 min and the ideal pH level was 4.0. Finally, we evaluated the entire treatment system by applying the MSSF after the sedimentation process, and found that the removal efficiencies of turbidity, BOD, COD, TSS, TDS, TP, and TN were 97.14, 94.80, 91.80, 98.96, 81.17, 81.12, and 82.50%, respectively. This is in addition to the filter's ability to remove bacteria counts at a rate of up to 98.93 and 99.13% of TCC and FCC, respectively.

Piggery wastewater treatment by solar photo-Fenton coupled with microalgae production

Pig farming generates highly polluted wastewater that requires effective treatment to minimize environmental damage. Microalgae can recover nutrients from piggery wastewater (PWW), but excessive nutrient and turbidity levels inhibit their growth. Solar photo-Fenton (PF) offer a sustainable and cost-effective pretreatment to allow microalgal growth for further PWW treatment. This study optimized the concentrations of PF reagents to minimise water and nutrient inputs while maintaining microalgae-based treatment efficiency. PF trials were conducted in pilot-scale raceway ponds under solar radiation, testing different concentrations of FeSO4 (4.48 and 8.95 mM) and H2O2 (77, 154, and 309 mM). Following PF, Tetradesmus obliquus was used in a biological treatment of PWW to recover the remaining nutrients. PF achieved high removal efficiencies for turbidity (97.6-99.5%), total organic carbon (59.2-77.1%), and chemical oxygen demand (83.8-94.7%), but ammonium was not significantly removed. Phosphorus was almost completely removed through iron precipitation during neutralisation. Lowering the H2O2 concentration from 309 to 77 mM did not compromise removal efficiency but reducing FeSO4 below 8.95 mM negatively affected the process. Consequently, 8.95 mM FeSO4 and 77 mM H2O2 were selected for microalgae production. The pretreated PWW could be recycled at least once for microalgal production, without nutrient supplementation, improving biomass productivity and PWW treatment, especially targeting ammonium. Phosphorus supplementation, however, did not significantly boost biomass productivity or treatment efficiency. Moreover, the iron sludge generated from PF pretreatment contained enough NPK to be repurposed as an organic fertilizer boosting sustainable agricultural practices. These findings encourage further investigation of this emerging combined technology towards wastewater treatment at large-scale.

Turbidity Removal Efficiency of Tannin Based Flocculants Derived from Different Agricultural Waste

Tannin-based flocculants have been investigated, produced, and commercialized as a promising product in water supply and wastewater treatment. This study compared turbidity removal efficiency of tannin-based flocculants produced from different agricultural waste. Tannin was extracted using ultrasonic method (ethanol 50%, 2 h, 500 kHz) and modified according to Mannich reaction using HCHO and NH4Cl. The coagulation and flocculation efficiencies were determined using Jar-tests on artificial wastewater with initial turbidity of 200 NTU. The results showed that at pH 7 and alum dosage of 5 ppm, turbidity removal efficiency of flocculants derived from longan pericarp, mimosa bark, green tea waste, and green banana peel were 93%, 92.7%, 92%, and 89.8%, respectively; corresponding to flocculant dosages of 10 ppm, 12 ppm, 8 ppm and 8 ppm. Production efficiency for green tea waste (9.4%), mimosa bark (7.1%), longan pericarp (4.6%) were much higher than that for green banana peel (0.5%). Based on the turbidity removal and production efficiencies as well as the optimal dosages of tannin-based flocculants, green tea waste was found to be the most potential material of all four agricultural waste to produce tannin-based flocculants.

Pilot-scale study of turbid particle evolutional/removal characteristics during coagulation-sedimentation-filtration (CSF): Effects of coagulant dosage and secondary dosing after breakage

Considering the limitations of treated water turbidity, a thorough understanding of the changes in turbid particle size distribution during coagulation-sedimentation-filtration (CSF) is crucial for enhancing the removal efficiency of particulate and dissolved contaminants from raw water. In this study, a pilot-scale experimental system was utilized to track the evolution of turbid particles and assess how the characteristics of these turbid particles affected the quality of treated water in the CSF processes under varying cases of polyaluminum chloride (PAC) coagulant dosage and secondary coagulant dosage after breakage. It was found that differently from the role of PAC coagulant dosage (without high-shear breakage), different levels of secondary coagulant dosing after breakage had minimal influence on the aggregate structure produced by mechanical stirring flocculation. During the overall CSF processes, the changing trend in the total particle number for the filtered water appeared to be more consistent with the corresponding changing trend for the settled water, as the PAC coagulant dosage increased. In addition, the combined effects of shear-induced breakage and secondary dosing could not only improve the removal efficiency of organic matter after inclined-tube sedimentation following mechanical stirring flocculation, but also enhance the removal efficiencies of water turbidity and particulate matter through sand filtration. In order to reduce the frequency of backwashing and extend the service life of the filter media, greater emphasis should be placed on detecting and removing the number of smaller-sized particles existing in the sixth unit of the flocculation tank together with the effluent of the sedimentation tank.

Optimization of Dissolved Air Flotation (DAF) process for the treatment of oily water from biodiesel production

Biodiesel production has become one of the most efficient ways of diversifying the energy matrix. However, the increase in biodiesel production increases the generation of wastewater. Therefore, this study aimed to characterize the wastewater generated in the biodiesel washing process, obtained by the alkaline transesterification of sunflower oil, and to evaluate its treatment by the dissolved air flotation (DAF) system, using a Central Composite Rotational Design (CCRD). The first DCCR was carried out with 4 independent variables: pH, Coagulant Dose (CD), Polymer Dose (PD), and Recirculation Rate (RR), with the response variables being apparent color removal and turbidity removal. Based on the results of the first DCCR, optimization tests were designed with DC and DP as independent variables and apparent color, turbidity, COD, and oil and grease (OG) as response variables. The process showed high apparent color and turbidity removal efficiency. The best results were obtained in tests 10 (DC = 1545 mg.L-1 and DP = 1050 mg.L-1) and 3 (DC = 700 mg.L-1 and DP = 8.8 mg.L-1), with the removal of 99.88% and 99.22%, respectively. For the COD and OG parameters, the best results were observed in tests 8 (DC= 555 mg.L-1 and DP= 6 mg.L-1) and 5 (DC= 1050 mg.L-1 and DP= 6 mg.L-1), with 98% and 99.42% removal, respectively. FAD treatment using the combination of coagulant and cationic polymer proved to be highly efficient in treating wastewater from biodiesel production.

Application of Thymus Species as Natural Coagulant for Elimination of Turbidity of Water and Its Comparison with the Conventional Coagulant

Introduction: The most important pollutant in surface water sources is turbidity. The aim of the study is to determine the most effective thyme plant extract as a natural coagulant to remove water turbidity and compare it with alum as a chemical coagulant.. Materials and Methods: In this study, plant extracts obtained from Thymus vulgaris (Tv), Thymus kotschyanus (Tk), and Thymus eriocalyx (Te) were used as natural coagulants for elimination of water turbidity. Then, the best of plant extract was confirmed by ninhydrin and FTIR analyses and the effect of simultaneous use of plant extract with chemical coagulant of aluminum sulfate (alum) was investigated in the hybrid ratio of 1:1, 2:1, and 1:2. Then, the effect of parameters include of pH, coagulant dose, turbidity removal efficiency, and the most suitable solvent for coagulant extraction were studied. Results: The results of this study showed that among the natural coagulants, Tv had a higher efficiency in elimination of water turbidity, and the highest amounts of turbidity elimination for Tv, alum, and Tv/alum hybrid coagulants was 94, 90, and 96, respectively. According to the results of this study, the most effective solvent for preparing plant extracts was 1M KCl solvent. Conclusion: The natural coagulant removes more turbidity from water than the chemical coagulant, and the simultaneous use of natural and chemical coagulants with a 1:1 ratio was more effective.

Efficient pulp and paper wastewater treatment using green tea-synthesized magnetite: Artificial intelligence and kinetic analysis

The pulp and paper industry generates pollutant-laden wastewater, requiring effective treatment to prevent environmental damage and enable sustainable reuse. This study investigated the use of green tea-synthesized magnetite (GT-Fe3O4) for treating pulp and paper wastewater. Characterization techniques, including SEM, XRD, FTIR and EDX, were employed to analyze the synthesized magnetite. Batch adsorption studies were conducted to examine the optimal operating conditions, including pH, contact time, adsorbent dose, and stirring rate, for achieving the best treatment performance. The treatment focused on reducing chemical oxygen demand (COD), total suspended solids (TSS), and turbidity in the wastewater. The adsorption data were evaluated using kinetic models, with the pseudo-second-order model providing the best fit. Additionally, an artificial intelligence prediction model (AIP) with a 4–10–1 structure was employed to predict the removal efficiencies. The optimal conditions for the treatment process were determined to be a pH of 6, a contact time of 60 min, a GT-Fe3O4 dose of 0.7 g/L, and a stirring rate of 150 rpm at room temperature. Under these conditions, the removal efficiencies for COD, TSS, and turbidity were 70.5 %, 65.4 %, and 38.8 %, respectively. The AIP model achieved an R² value range of 0.978 to 0.982, showing high prediction accuracy. The study demonstrates that GT-Fe3O4 effectively reduces pollutants in pulp and paper wastewater.