Turbidity Reduction Research Articles

Exploring Moringa oleifera: Green Solutions for Sustainable Wastewater Treatment and Agricultural Advancement

Increasing concerns over water pollution have driven the search for sustainable wastewater treatment alternatives. This study evaluates the effectiveness of two coagulants derived from Moringa oleifera seeds–powder and extract–as sustainable solutions for wastewater reuse in agriculture. Comparative experiments were conducted using aluminum sulfate, a conventional coagulant, at various doses under controlled laboratory conditions. The results demonstrated that both M. oleifera-based coagulants were highly effective, achieving turbidity reductions of 97% and 99%, respectively. Notably, the powder form required lower doses than the extract but had longer sedimentation times. Further detailed analyses at optimized doses (500 mg/500 mL for powder and 12.5 mL/500 mL for extract) met international standards for wastewater quality in agricultural irrigation. Comprehensive analyses encompassing pH, turbidity, COD, BOD5, TSS, DO, conductivity, NO2−, NO3−, SO42−, PO43−, and fecal and total coliforms consistently adhered to stringent criteria, confirming the effectiveness of M. oleifera-derived coagulants. These findings highlight the potential of M. oleifera in wastewater treatment, offering sustainable solutions to environmental challenges and enhancing food security in resource-limited regions. Our research supports the broader adoption of these eco-friendly alternatives, which could significantly reduce water scarcity and promote sustainable agricultural practices, addressing critical environmental concerns.

Inhibition of the Hyaluronidase Enzyme Produced by Staphylococcus Bacteria Using Vasicine Alkaloids of the Vasica Plant

Hyaluronidase is an enzyme that breaks down primarily hyaluronic acid, thereby disrupting the structural integrity of the extracellular matrix (ECM) found in connective tissues, which is considered a virulence factor. The aim of this research was to study the effect of a plant-active compound (vasicine) that was separated from a plant sample as an inhibitor agent for the hyaluronidase enzyme that was isolated from Staphylococcus aureus, which is considered a virulence factor. 120 samples were randomly isolated from infected burns. The isolates showing highly hydrolyzed zones were identified. Cell growth as well as hyaluronidase activity are measured spectrophotometrically by the turbidity reduction assay. The results showed that 100 out of 120 clinical samples grew bacteria when cultured on blood agar medium. Also, it was found that of the 100 isolates, 56 (56%) belonged to S. aureus and had an inhibitory zone of hyaluronidase of 5–26 mm, and the inhibitory zone was increasing over time.

Practical implications of adding powdered activated carbon in advanced wastewater treatment for process and plant design

ABSTRACT The addition of powdered activated carbon (PAC) in advanced wastewater treatment is increasingly recognized for its effectiveness in removing micropollutants from secondary effluents. This study investigates the implications of PAC dosing on treatment performance, particularly in terms of natural and effluent organic matter (OM) removal, turbidity reduction, and sludge characteristics. Results indicate that while PAC incorporation significantly enhances the adsorption of OM, it necessitates higher coagulant dosages to achieve comparable or improved turbidity levels. The study also reveals that lower pH levels facilitate the removal of OM, thereby increasing the availability of adsorption sites on PAC for micropollutants. Moreover, PAC addition results in the formation of larger, denser flocs that settle faster, leading to a reduction in sludge volume by approximately 20%. However, the increased coagulant demand and the subsequent rise in sludge volume highlight the need for the optimized process design to balance treatment efficiency with operational costs. This research provides valuable insights for the design and operation of wastewater treatment plants, emphasizing the importance of tailored coagulant dosing and process adjustments when integrating PAC into existing treatment frameworks.

Physico-chemical and microbiological parameters of natural, industrial recycled water and its treatment

Background: Under conditions of anthropogenic impact, the chemical composition of water in surface rivers and groundwater bodies is subjected to pollution, which leads not only to a decrease in water quality, but also to an increase in the number of pathogenic and opportunistic bacteria. Aim: The purpose of this work is to study the physicochemical and microbiological parameters of natural and industrial recycled water before and after treatment with coagulants based on activated aluminum alloys. Materials and methods: As natural waters were analyzed: natural waters from water intake “Almaty SU”, “Medeu” tract, Zhaiyk river, from the well of experimental metallurgical production of IMOB. As recycled water was analyzed water taken from the water treatment unit of deep oil refining production. Turbidity was measured using HACH 2100Q turbidimeter and 2100Qis turbidimeter (USA). Cell morphology of microorganism cultures was studied by light microscopy using a MicroOptix MX-1150 (T) stereoscopic-sotrinocular microscope. Results: An effective and technologically simple method of obtaining aluminum polyoxychloride with the content of the main substance from 33 to 41.0% by Al2O3 and basicity from 55.1 to 66.5% has been developed. The method consists in dissolution of aluminum alloy activated by metal-activators (indium, gallium, tin) in the amount of 0.5–1.0 wt.% of each in 3% HCl. Physico-chemical and microbiological parameters of natural and industrial recycled water have been studied. The efficiency of the obtained aluminum polyoxychloride for treatment and conditioning of drinking water and industrial recycled water was evaluated. Conclusion: Unique alloys with high energy characteristics based on aluminum containing indium, gallium, tin from 0.5–1.0 wt.% have been created. The alloy has high activity in various oxidizing media (water, hydrochloric acid). A technologically simple method of obtaining aluminum polyoxychloride has been developed. Chemical and microbiological composition of natural and industrial recycled water has been studied. Coagulants based on activated aluminum alloys are effective in the processes of conditioning and purification of natural and recycled water from toxic compounds, have bactericidal activity, the level of gram-negative bacteria is reduced to 73%, gram-positive bacteria to 84% and to 96% of other groups of microorganisms. Fungi and yeasts (Mucor, Fusarium) were not detected after water treatment. Efficiency of water turbidity reduction reaches 90–99%, permanganate oxidizability up to 93%.

Reduction of organic matter and disinfection by products formation at surface water treatment plants in Egypt

ABSTRACT Although the removal of colloidal particles continues to be an important reason for using coagulation, currently a newer approach, the removal of organic matter to reduce the formation of disinfection byproducts (DBPs) such as trihalomethanes (THMs) are suspected carcinogens. Inefficient removal of total organic carbon (TOC) leads to the formation of carcinogenic THMs. This motivates the research efforts to find a way to reduce them in potable water. The first objective of this research is monitoring the water quality (raw and produced) for selected three water treatment plants within Giza Governorate to reveal the most polluted site (high TOC in the raw water and THMs in the treated water) in the study areas. The second objective of this study is enhancing coagulation to reduce TOC and THMs from surface water treating. In this study, two different coagulants aluminum sulfate (alum), and ferric chloride were tested under different conditions of pH and coagulant concentration to determine their effectiveness for removal of TOC, THMs and turbidity. Optimum values for the mentioned conditions were used to achieve the maximum reduction for TOC and THMs in Al-Ayat drinking water treatment plant (DWTP) which recorded the highest concentration of TOC and THMs. Ferric chloride as a coagulant achieved the maximum removal percentage % of TOC, THMs and turbidity as 79%, 82% and 94%, respectively, at ferric chloride dose 100 mg/L, while alum as a coagulant recorded the maximum removal percentage % of TOC, THMs and turbidity as 46%, 52% and 91%, respectively, at alum dose 100 mg/L. The results indicated that ferric chloride as a coagulant has the highest efficiency reduction of TOC, THMs and turbidity if compared to alum with the same dose added.

Electrocoagulation-Electro-Fenton hybrid system for dairy wastewater treatment: A comprehensive test and analysis, in aqueous solution

This study aimed to assess the efficacy of a treatment system combining electrocoagulation (EC) and Electro-Fenton (EF) for the remediation of the wastewater dairy industry. Synthetic samples simulating dairy effluent were prepared and subjected to characterization for turbidity, chemistry oxygen demand (COD), and pH. The Box-Behnken design, comprising operating parameters such as electric current (0.5 to 1.5 A), electrolysis time (5 to 17.5 min), initial pH (4.0 to 9.0), and hydrogen peroxide concentration (0 to 9.0 g/L), with three replications at the central point. The combined treatment was conducted in a batch reactor using iron electrodes and subsequently filtered using a qualitative filter paper. Analysis revealed the significance of electric current, electrolysis time, and peroxide concentration at a 5 % probability level for COD reduction. A reduction of 80 % in chemical oxygen demand (COD) and a 99 % reduction in turbidity were achieved by maintaining the original pH of the wastewater and using a combination of an electric current greater than 1 A and an electrolysis time of 11.5 min, without the addition of hydrogen peroxide. The results showed that the treatment followed the standards of the Brazilian legislation.

Integration of experimental and intelligent modeling for optimizing iron electrocoagulation-flocculation recovery of aquafarm effluent

The present study integrates experimental and intelligent models in the modeling and optimization of the iron electrode-based electrocoagulation-flocculation (EC-FLC) process for the treatment of aquafarm effluent (AFE). The modeling was done using Response Surface Methodology (RSM), Artificial Neural Networks (ANN), and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), while the optimization was performed with Particle Swarm Optimization (PSO). The physicochemical properties of AFE were determined before and post-treatment to assess the effectiveness of the process. Central composite design (CCD) embedded in RSM was employed for experimental design. ANFIS model utilized the grid partition and ANN employed a multi-layer perceptron-based feed-forward architecture. The statistical analysis revealed superior prediction accuracy in the decreasing order ANFIS (R2: 0.9968, AAD: 0.0009, RMSE: 0.2373), ANN (R²: 0.9896, AAD: 0.0023, RMSE: 0.4388), and RSM (R²: 0.9655, AAD: 0.0067, RMSE: 0.7764), demonstrating the superiority of ANFIS model. Models’ reliability were validated by the strong correlation between the actual/predicted values of turbidity removal. The experimentally validated optimization solutions for turbidity were RSM numerical (96.71 %), RSM-PSO (97.46 %), ANN-PSO (98.83 %), and ANFIS-PSO (99.01 %). Post-treatment analysis revealed significant reductions in turbidity, nutrient content, and organic matter. These findings demonstrated the effectiveness of the intelligent tools in the modeling/optimization of EC-FLC recovery of AFE.

Experimental investigation of single slope solar still for culinary wastewater treatment

Solar still desalination (SD) offers a sustainable method for purifying contaminated water, despite its productivity limitations. This study proposes an effective treatment process for culinary wastewater (CWW), multilayer-filtered culinary wastewater (MFCWW), and borewell water. We conducted a comprehensive experimental analysis comparing key SD characteristics, including evaporative heat transfer, efficiency, productivity, exergy, and water quality parameters, across these water sources. Our findings reveal that integrating multilayer filtration with CWW significantly improves efficiency, productivity, turbidity reduction, and hardness removal compared with untreated CWW. Notably, MFCWW has emerged as the most promising modification, demonstrating enhanced solar still performance over conventional SD processes. This study highlights the potential of combining multilayer filtration with solar desalination as an innovative approach to improve water purification outcomes, particularly for culinary wastewater treatment.

Turbidity Removal from Sullage Wastewater Using Musa paradisiaca Peels as a Natural Coagulant

The use of inorganic commercial coagulants for water and wastewater clarification has been linked to the prevalence of human health and environmental issues. Natural coagulants are currently being explored as an alternative option for replacing synthetic coagulants. This present study, examines the use of Musa paradisiaca peels as a natural based coagulant for turbidity reduction in sullage wastewater. Musa paradisiaca peels, alum and blended were used in the study as coagulants for sullage wastewater clarification. The blended coagulant was prepared by combining the Alum and Musa paradisiaca peel powder in a ratio of 1:1. The sullage wastewater used in the study had an initial concentration of 151.8 NTU and was sourced within the University premises. The batch experimental procedure to examine the effectiveness of the natural coagulant was used. The study results show that the highest turbidity removal was for alum, blended, and coagulant, from 151.8 to 1.1 NTU, 151.8 to 14.43 NTU, and 151.8 to 29.32 NTU respectively. The maximum results for the effect of contact time on the rate of turbidity removal were attained at 6 h for all coagulants. The effect of natural coagulant performance on pH medium has indicated that it favours the acidic solution. The results obtained in this study recommend the efficiency and value of Musa paradisiaca peels as coagulant. The use of Musa paradisiaca peels as a natural coagulant offers a sustainable and cost-effective solution for the treatment of sullage wastewater. The use of Musa paradisiaca as a natural coagulant provides an alternative solution for replacing synthetic coagulants and overcomes health challenges associated with its usage, offers water treatment at low cost and reduces environmental issues associated with agri-food waste disposal, thereby promoting sustainable waste management.

Assessment of an Advanced Water Filtration System for Enhanced Water Purification

The study confirms the effectiveness of a state-of-the-art water filtration system in purifying urban tap water, river water, and groundwater. The system, which uses activated carbon, ceramic, and reverse osmosis (RO) filtration, significantly improved water quality by removing physical, chemical, and biological contaminants. Key results include: The system achieves a turbidity reduction of up to 99.5%, adhering to WHO standards. The system removes over 96% of volatile organic compounds (VOCs) and chlorine, and more than 99% of heavy metals like lead and arsenic. The water is completely free of harmful bacteria, guaranteeing its microbiologic safety. There has been a 98.2% reduction in total dissolved solids (TDS) in groundwater. The study highlights the system's adaptability to diverse environments, including urban, rural, and industrial settings. Future research could focus on improving the system's energy efficiency and sustainability.

Assessment of the physiochemical properties and sustainability of locally produced ceramic G-filter in a long term experiment

In India, Ceramic Water Filters (CWF) named G-filters are becoming a point-of-use household water treatment solution. The filter's reliability may be primarily characterized by the filtrate turbidity and microbial removal efficiency. The temperature and moisture gradients of the location affect its performance. This paper describes a 19-week laboratory investigation of G-filters simulating field conditions. The basic objective during the study was to ascertain the effective useable life of the filter. The discharge rate and turbidity reduction ability of the filters are studied in depth. The G-filters were prepared using locally available salty clay and sawdust taken in equal volume fractions. A total of 30 filters with a 9-liter capacity each were used for the experiments. The results showed that CWFs can reduce turbidity effectively. The influent water used for the study had a mean turbidity of 7.65 NTU, which reduced in the range of 0.03 NTU to 1.03 NTU. Over the course of four months, the average flow rate decreased from 1.94 Lh-1 to 0.93 Lh-1. Although a soft brushing of filters improved the filtration rate but that too failed in the long run. Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption measurements were used to determine the variation in pore size of filters with time. An average pore radius of 2.91 nm was found in the original filter that has not been used for filtration experiments. Moreover, an average pore radius of 1.77 nm, 1.21 nm, and 1.22 nm were reported in G-filters through which 427.5 L, 807.5 L, and 1035.5 L, respectively, of water were passed. This reduction in pore size is attributed to the clogging of pores over a period of time. This study aims to collect performance data to establish a scientific model using statistical analysis for implementing CWF technology in developing nations.

Development of an efficient pretreatment process and multi-functional acetate co-metabolism strategy for the treatment of high strength biogas slurry using a newly isolated Chlorella sorokiniana

The efficient treatment of biogas slurry (BS) to meet the government’s discharge standards is a major challenge for most livestock and poultry enterprises. Although microalgae-based wastewater treatment has many significant benefits over traditional technologies, the poor ammonium tolerance of regular algal species, the pH imbalance during microalgae cultivation, and the complex and expensive BS pretreatment process greatly limit its application in BS treatment. Aimed at these issues, this study firstly isolated a robust Chlorella sp. with strong ammonium and acidic tolerance, as well as heterotrophy ability. To facilitate optimal pH stability and growth enhancement, a co-metabolism cultivation strategy based on the addition of 0.1 g·L-1 acetate in the form of fed-batch was developed. In addition, an efficient pretreatment process integrating ammonia reduction by air stripping with turbidity and chromaticity reduction by acidic precipitation was developed for the elimination of inhibitory factors of microalgal growth in BS. The isolated Chlorella sp. was capable of growing in the pretreated real BS and no growth inhibition was observed even in the undiluted BS. The acetate co-metabolism cultivation strategy obviously enhanced cell growth and pollutant removal and both NH4+ and total phosphorus were reduced to meet the discharge standards of China via 2.5-fold dilutions of BS. The accumulation of high-value biomass could not only fully cover the cost of wastewater treatment, but also bring significant returns. The net profit from treating 1 m3 of BS reached $ 116.2. This study provides a simple and efficient packaged process for the treatment of high strength BS and is expected to greatly reduce the process cost of BS.

Supervised machine learning for understanding and predicting the status of bistable eukaryotic plankton community in urbanized rivers

Understanding and predicting the ecological status of urbanized rivers is crucial for their restoration and management. However, the complex and nonlinear nature of ecological responses poses a challenge to the development of predictive models. Here, the study investigated and predicted the status of eukaryotic plankton communities in urbanized rivers by coupling environmental DNA metabarcoding, the alternative stable states theory, and supervised machine learning (SML) models. The results revealed two distinct states of eukaryotic plankton communities under similar environmental conditions: one state was characterized by the enrichment of a diverse phytoplankton population and the high relative abundance of protozoa, whereas the alternative state was characterized by abundant phytoplankton and fungi with an associated risk of algal blooms. Turbidity was identified as a key driver based on the SML model and Mantel test. Potential analysis demonstrated that the response pattern of eukaryotic plankton communities to turbidity was thresholds with hysteresis (Threshold1 = 17 NTU, Threshold2 = 24 NTU). A reduction in turbidity induced a regime shift in the eukaryotic plankton community toward an alternative state associated with a risk of algal blooms. In the prediction of ecological status, both SML models showed excellent performance (R2 > 0.80, RMSE < 0.1, Kappa > 0.70). Additionally, SHapley Additive exPlanations analysis identified turbidity, chlorophyll-a, chemical oxygen demand (COD), ammonia nitrogen and green algae's amplicon sequence variants as crucial features for prediction, with turbidity and COD showing a synergistic effect on ecological status. A framework was further proposed to enhance the understanding and prediction of ecological status in urbanized rivers. The obtained results of this study demonstrated the feasibility of using SML models to predict and explain the ecological status of urbanized rivers with alternative stable states. This provides valuable insights for the application of SML models in the restoration and management of urbanized rivers.

Intensive coagulation of secondary effluent to mitigate reverse osmosis membrane fouling at low temperatures: Strategies of pre-oxidation and coagulant aids addition

Conventional coagulation-sedimentation, typically used as a pretreatment for ultrafiltration-reverse osmosis, is ineffective in solving the problem of reverse osmosis membrane fouling at low temperatures. In this study, the coagulation enhancement effect of pre-oxidation and the addition of coagulant aids on conventional coagulation with polyaluminum chloride as a coagulant was investigated. The results showed that the addition of fly ash, powdered activated carbon, or diatomite as coagulant aids improved the reduction of turbidity, dissolved organic carbon (DOC), and ultraviolet absorbance at 254 nm (UV254), and also reduced the residual content of dissolved aluminum ions. Among them, diatomite was superior. Pre-oxidation before conventional coagulation increased the reduction of turbidity and UV254 by about 50 % and doubled the removal of proteins, polysaccharides, and DOC compared to conventional coagulation. Ozone was superior to sodium hypochlorite. The combination of ozone pre-oxidation and diatomite addition with conventional coagulation further increased the pollutant removal rate, with the removal rates of turbidity, UV254, polysaccharides, proteins, and DOC reaching 82.20 %, 52.35 %, 26.34 %, 24.89 %, and 26.38 %, respectively. In addition, the residual content of dissolved aluminum ions decreased to 0.84 mg/L. The reverse osmosis filtration simulation test showed that pretreating the feed water with the enhanced coagulation by the combination of ozone pre-oxidation and diatomite addition resulted in a slower decrease in membrane flux, reduced foulant content on the membrane surface, and the smallest increase in contact angle. The results of this research may offer a viable pretreatment method to reduce fouling in reverse osmosis membranes operating at low temperatures.

Development of a limestone-based ballasted material for enhanced co-removal of turbidity and fluoride from coal mine water: An efficacy study

The rapid progression of coal mining technology in recent years has resulted to the discharge of mine water with excessively high levels of turbidity and fluoride, presenting a complex contamination issue. This study develop an innovative limestone-based ballasted material, integrating it with ballasted flocculation technology. The synergistic effects of surface flocculation and adsorption have enabled the simultaneous and efficient removal of high concentrations of turbidity and fluoride. The influence of various parameters, including the dosage of the coagulant, flocculant, ballasted material, and the stability under long-term continuous operation, on the performance of this new technology was investigated. Findings indicate that an increase in the dosage of the coagulant, polyaluminum chloride (PAC), positively affects the removal of turbidity and fluoride ions, with an optimal dosage of 60 mg/L. The addition of polyacrylamide (PAM) showed that both conventional and ballasted coagulation techniques exhibit an initial increase followed by a decrease in turbidity removal efficiency, and an ascending trend in fluoride removal efficiency, with an optimal PAM dosage of 1.0 mg/L. The dosage of the new ballasted material was determined based on the initial water turbidity and fluoride concentrations, an increase in its dosage led to a progressive reduction in effluent turbidity and a corresponding increase in fluoride removal. A 30-day continuous operation confirmed the stability of the new process, with a treatment cost of approximately 2.67 $/t. The pseudo-first-order kinetic model and the Langmuir adsorption isotherm equation provided satisfactory fits to the treatment data, suggesting that both conventional and ballasted coagulation involve a combination of surface adsorption and intraparticle diffusion mechanisms for the removal of turbidity and fluoride.

Optimization of coagulation-flocculation in urban water treatment using Moringa oleifera

Using a safe, easy-to-apply, and cost-effective flocculant to substitute alum is imperative for broadening and improving water quality in rural areas where conventional water treatment methods are inaccessible. This study aimed to assess the efficacy of Moringa oleifera seeds (MOS) in treating urban wastewater. The experiment involved adding random quantities ranging from 0.1 to 0.5 g/500 ml of water. Various properties of the wastewater were evaluated, including turbidity, chemical oxygen demand (COD), and color. The optimal dosage of MOS was determined to be 0.3 g/ 500 ml, resulting in the most significant reduction in color and turbidity. The highest reduction percentage was observed for turbidity (87.5 %), followed by COD (58.8 %) and color (49.76 %). The characteristics of dissolved organic matter notably influence the coagulation behavior of MOS. Based on these findings, the study proposed a coagulation mechanism for Moringa.

Role of fabrication parameters on microstructure and permeability of geopolymer microfilters

A new method for preparing geopolymer filtrations was suggested, using silica fume in an alkali activator as an environmentally and economically sustainable material. The geopolymer filtration was fabricated by activating metakaolin with a blend of sodium hydroxide and silica fume. Different phase structures and microstructures were fabricated with varying preparation parameters, such as silica fume content, Na2O/Al2O3 molar ratios, and curing temperatures. The filters were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, and mercury intrusion porosimetry. Filters were tested for pure water flux, compressive strength, and wastewater permeability using industrial textile wastewater. The geopolymer-zeolite composite filter, including 10 wt% silica fume, Na2O/Al2O3 molar ratio of 1, and curing temperature of 60 °C exhibited the highest pure water permeability of 144 L/m2.h.bar, wastewater permeability of 77 L/m2.h.bar, and achieved 95.5 % turbidity reduction for the textile wastewater.

Removal of malachite green from an aqueous environment using chitosan-xanthan gum coagulation system: A response surface methodology approach

Natural coagulants provide a safe and sustainable alternative for water treatment. Our study used shrimp shell-derived chitosan combined with xanthan gum to remove malachite green dye from water. Using a Box-Behnken design, we optimized parameters, achieving up to 99.7 % dye removal under optimal conditions: chitosan (1.75 mg/L), xanthan gum (1.73 %–3.0 %), dye (5–27.5 mg/L), pH 6.0, stirring period (5–7.5 min), and stirring rate (105 rpm). Key factors affecting sedimentation included xanthan gum dosage and its interactions with pH and stirring rate. SEM and FT-IR analyses characterized dye-polymer interactions. Pilot-scale tests on aquaculture wastewater showed significant turbidity reduction and enhanced dye removal in 15 L volumes. Toxicity assessments post remediation was performed on Artemia salina as a model organism and hatching efficiency and survival were essential parameters studied. Our findings highlight the potential for sustainable dye recovery and reuse in wastewater treatment.

Direct Screening of PET Hydrolase Activity in Culture Medium Based on Turbidity Reduction.

The development of an efficient screening method for the activity of PET-degrading enzymes represents a significant technological advance in the field of enzyme research, with the potential to facilitate the advancement of enzymes for PET recycling. By examining the stable conditions of PET suspension and enzyme production conditions, we developed a method to quantify PET-degrading enzyme activity in E. coli culture medium using turbidity reduction as an indicator. High PET concentration or ionic strength caused aggregation of PET, and the best condition for activity detection was 0.5 mg mL-1 PET in 50 mM sodium phosphate pH 7.0. Preculture of E. coli increased the purity of enzyme secreted in medium. To evaluate the screening method, 720 colonies of the PET2-7M-H229X-F233X mutant library were analyzed and three candidates of high-activity mutants were obtained. The thermostability of the mutants could also be easily measured by measuring the residual activity after heat treatment. The H229T-F233M mutant showed 3.4 times higher degradation rate against PET film than the template enzyme at the initial time. The molecular dynamics simulation implied that the F233M mutation makes space for making an α helix and that the H229T mutation resolved the steric hindrance with Trp199. These mutations were speculated to change the angle of the Trp199 side chain of PET2 to an angle similar to that of the Trp185 of IsPETase, making it suitable for PET binding to the active center. Screening of activity using PET suspensions is compatible with robotic automation and is expected to be useful for validating computationally predicted mutations.

Wastewater treatment using a microalgae consortium mainly composed of chlorella, in Mexico

The bioremediation capacity of microalgae found in the wastewater channels in Irrigation District 03 (DR03) in Mexico was studied. The study evaluated the effect of pH, aeration, light intensity, and water source on the productivity, culture time, and composition of the microalgal biomass, predominantly made up of Chlorella vulgaris spp. Parameters such as Chemical Oxygen Demand (COD), total solids (TS), and turbidity were monitored to assess the efficiency and bioremediation capacity of the microbial consortium. The yield production of microalgal biomass was measured to evaluate the amount produced per unit volume of treated water. Two culture conditions were assessed: uncontrolled and controlled conditions of aeration and lighting. Under controlled culture conditions, a productivity of 0.031 g L−1 d−1 biomass with 17% lipidic fraction and 37.65% ash content was observed, along with a reduction in COD and turbidity by 57 and 85%, respectively. A biomass productivity of 0.024 g L−1 d−1 was obtained.