Turbid water treatment using deshelled carica papaya seed: Analysis via factorial design

Natural coagulants are proven to be a good alternative to conventional coagulants with the removal of various pollutants and are environmentally friendly. Despite its advantages, the least studies were carried out on local agro-wastes such as papaya seeds as natural coagulants concerning different operational factors. The study analyzes the main and interactions effect between the coagulant dosage, initial turbidity, and pH on deshelled Carica papaya seeds for turbid water treatment. A 2-level factorial design was used to investigate the main and interaction effects of the main operational factors, viz. coagulant dosage (50-200 mg/L), pH (3-7), and initial turbidity (100-500 NTU) on the turbidity removal of the synthetic turbid water. Based on individual performance, the results suggested that initial turbidity and pH are the most significant factors among the investigated operational factors. In combination, all interactions are significant, but the interaction between initial turbidity and pH is most significant, with 97.2% turbidity removal. Upon application of Carica papaya seed as a natural coagulant in water and wastewater treatment, these operating variables and their interactions are best to be considered

Potential of Carica papaya Seed-Derived Bio-Coagulant to Remove Turbidity from Polluted Water Assessed through Experimental and Modeling-Based Study

It is important to develop renewable bio-coagulants to treat turbid water and efficient use of these bio-coagulants requires process optimization to achieve robustness. This study was conducted to optimize the coagulation process using bio-coagulant of deshelled Carica papaya seeds by employing response surface methodology (RSM). This bio-coagulant was extracted by a chemical-free solvent. The experiments were conducted using the Central Composite Design (CCD). Initially, the functional groups and protein content of the bio-coagulant were analyzed. The Fourier Transform Infrared Spectroscopy analysis showed that the bio-coagulant contained OH, C=O and C-O functional groups, which enabled the protein to become polyelectrolyte. The highest efficiency of the bio-coagulant was obtained at dosage of 196 mg/L, pH 4.0 and initial turbidity of 500 NTU. At the optimum conditions, the bio-coagulant achieved 88% turbidity removal with a corresponding 83% coagulation activity. These findings suggested that the deshelled Carica papaya seeds have potential as a promising bio-coagulant in treating the polluted water

Carica papaya seeds-derived coagulant for water treatment

Papaya, or also known as carica papaya is a common fruit grown in many tropical climate countries. Following its mass consumption, papaya fruit wastes such as peels and seeds are generated around 15 to 20% of the fruit’s weight. Hence, the needs arise to either to reduce waste or reuse it into other forms that can be beneficial. Natural coagulants are gaining interest as they are environmentally friendly compared to chemical coagulants. Therefore, the aim of this study is to utilize discarded papaya seeds in becoming the natural coagulant to treat turbid water. The objective of this study is to characterize physico-chemical and morphological properties of carica papaya seed-derived natural coagulant, to determine the optimum operating conditions of carica papaya seed-derived natural coagulant in treating synthetic water and to investigate performance efficiency of carica papaya seeds-derived natural coagulant in treating different classes of river water. Initially, the collected carica papaya seeds were processed by washing, deshelling, drying at 50°C for 24 hours and grinding prior to physico-chemical and morphological characterization. Jar test was conducted based on 2-level factorial design, followed by Response Surface Methodology (RSM) in order to determine the optimum operating conditions of coagulant dosage, pH and initial turbidity on turbidity removal and coagulation activity. For comparison purpose, alum was used. The effectiveness of carica papaya seeds-derived natural coagulant was then tested on different classes of rivers. Class III, Class IV and Class V river water was represented by Skudai River, Melana River and Tukang Batu River respectively. The effectiveness of carica papaya seeds as coagulant was determined based on the removal of turbidity, chemical oxygen demand (COD), ammoniacal nitrogen, nitrite, nitrate, phosphorus and coliforms. Based on the findings, the deshelled carica papaya seeds contained 3.9% moisture content, which resulted towards high yield of 99.2%. The isoelectric point of carica papaya seeds derived natural coagulant was at pH 6 while the surface charge was recorded as +0.4 meq/g. The coagulant also contained minimum concentration of iron and sufficiently high protein content of 363 mg/g. Factorial analysis of carica papaya seeds-derived coagulant revealed that most main and interaction terms are significant, excluding interaction between pH and initial turbidity on turbidity removal. Based on the RSM analysis, at optimum condition of 196 mg/L dosage, pH 4 and initial turbidity of 500 NTU, the papaya seeds were capable to remove turbidity up to 93% with coagulation activity of 85%. Actual observations using the optimum conditions resulted to 88% turbidity removal and 83% coagulation activity. Meanwhile for alum, at optimum condition of 197 mg/L dosage, pH 6.3 and initial turbidity of 425 NTU, the recorded turbidity removal and coagulation activity was 98% and 98%, respectively. Actual observations using the optimum conditions resulted to 94% turbidity removal and 93% coagulation activity. Carica papaya seeds derived natural coagulants were also able to obtain high removal turbidity (87.6%), nitrite (86.2%) and nitrate (82.3%) for river of Class III while for river of Class IV, the natural coagulant obtained higher removal of only turbidity (88.3%) and nitrite (92.2%). This natural coagulant was also able to remove 57.6% and 62.1% of total coliform and Escherichia coli, respectively from Class III river water, which then verifies the antimicrobial properties of the studied natural coagulant. In conclusion, carica papaya seeds have proved its potential ability in becoming effective natural coagulant and able to treat synthetic kaolin water as well as river water of Class IV and below at designated optimum conditions

Deshelled Carica papaya seeds as natural coagulant for improvement quality of river water

This study evaluated the efficiency of deshelled papaya seeds as the natural coagulant in improving quality of river water. The deshelled papaya seeds biomass was mainly characterized for functional groups using FTIR, surface charge and protein content. Coagulation and flocculation tests were conducted using batch test for various dosages and pH values. The optimum dosage and pH were then tested in treating river of Class III to Class V. The functional groups in deshelled papaya seeds were O-H, C=O and C-O groups. The surface charge and protein content was +0.4 meq/g and 363 mg/g, respectively. The deshelled papaya seeds coagulant was able to remove turbidity up to 87.6 and 88.3% for river of Class III and Class IV, respectively, as well as 57.6 and 62.1% of total coliform and Escherichia coli, respectively, from Class III river at dosage 196 mg/L and pH 4. This study demonstrated that the deshelled Carica papaya seedsderived coagulant is capable in treating common pollutants of river and simultaneously shows antibacterial properties