A Comparative Study ofStrychnos potatorumand Chemical Coagulants in the Treatment of Paint and Industrial Effluents: An Alternate Solution

Investigation on the removal of contaminants from washing machine discharge using Strychnos potatorum (clearing nut) - A potential purifying agent

The objective of the present study is to develop eco-friendly purifying agents from natural materials, Strychnos potatorum (SP) - a coagulant. The seeds of SP were used for wastewater treatment (washing machine effluent). Physico-chemical parameters like turbidity, total dissolved solids (TDS), electrical conductivity (EC), pH, calcium (Ca2+), magnesium (Mg2+) and phosphate (PO43-) were tested and the data obtained were compared with BIS standards. In the current work, physical and chemical parameters have been examined to determine the quality of water for washing machine discharge, before and after treatment (coagulation) using SP seeds. The testing procedure was carried out using a Jar test of coagulant mass 1000 mg/L with rapid mixing at 150 rpm for 5 min, slow mixing at 30 rpm for 25 min and a settling period of 1 h. Coagulation results were reported for the use of SP seeds, where the effectiveness of removing turbidity and PO43- was determined to be 81.54 and 41.45%. The presence of various functional groups in SP seed was assessed by fourier transform infrared (FT-IR) spectroscopy. Qualitative identification of phytochemical constituents of seed extract for this species was also carried out. The experimental findings strongly highlighted the ability of SP seeds to remove turbidity and PO43- from wastewater.

Equilibrium Isotherms, Kinetics, and Thermodynamic Mechanisms of a Novel Polyacrylamide-Strychnos potatorum Seed-Derived Activated Carbon Composite for Aqueous Hardness Removal

Hardness in water is responsible for both residential and industrial problems. Moreover, drinking hard water is suspected as the main cause of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. The major constituents that are responsible for water hardness are calcium and magnesium ions. In this study, a composite was synthesized using activated carbon of Strychnos potatorum seeds (ACSP) and acrylamide to remove hardness in drinking water. The synthesized composite was characterized using Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy and scanning electron microscope (SEM). According to this study, the process of removal of hardness depends on the contact time, adsorbent dosage, initial contents, and pH of the solution. The adsorption data were well fitted to the Freundlich isotherm and the pseudo-second-order kinetic models. Furthermore, environmental samples collected from Anuradhapura, Sri Lanka, which is well known for water with high hardness, were treated with an adsorbent, and hardness was reduced effectively. Moreover, the adsorption appeared to be spontaneous in nature. Finally, it can be concluded that this adsorbent can be used as an effective hardness-removing agent.

Elucidation the influence of design variables on coagulation-flocculation mechanisms in the lab-scale bio-coagulation on toxic industrial effluent treatment

Bio-coagulants are environmentally friendly substances that have shown potential in removing organic and inorganic contaminants from wastewater from the Imitation Paint Industry. Under the optimized conditions, the use of the three bio-coagulants (of plant origin), Strychnos potatorum, Cactus opuntia and Portunus sanguinolentus (crab) shell (of animal origin) were evaluated, and their removal mechanism was based on kinetic models and adsorption isotherms. The error analysis method was used to find the best isotherm fit. In addition, the kinetic model parameters showed the absence of chemisorption and confirmed the existence of pore diffusion. The interaction between coagulant and pollutant, the type, homogeneity and intensity of the coagulation process, the pollutant absorption capacity of the coagulant were evaluated with the aid of the adsorption isotherm models. From the Pseudo first-order kinetic model an equilibrium pollutant uptake (mg/g) was marked as 598, 554 and 597 for Strychnos potatorum, Cactus opuntia and Portunus sanguinolentus respectively. The better affinity between the pollutants and the bio coagulants were observed through the lower values of Langmuir isotherm constant k_L. The adsorption intensity from Freundlich model (n_F) were ranged between 1 and 10 for all the listed coagulants, which revealed the physisorption behavior and heterogeneous mechanism of removal. With these results, it would be possible to conduct scale-up studies to adopt the process for practical systems.

Towards zero waste production in the paint industry wastewater using an agro-based material in the treatment train

An attempt has been made to evaluate the use of natural, agro-based material, Moringa oleifera as a coagulant in the treatment of recreated water-based paint effluent. The treatment train sequence comprising coagulation, flocculation, sedimentation, sand filtration, and membrane filtration was used. The efficiency was evaluated in terms of color and turbidity. The influence of experimental parameters such as eluent type, eluent concentration, coagulant dose, coagulant-eluate volume, initial effluent pH, and initial effluent concentration was examined. The recommended conditions to yield maximum removal efficiency are 80 mL of eluate prepared using 3 g of M. oleifera seed powder and 1 N NaCl, under actual pH, to treat a liter of effluent. The treated supernatant from coagulation unit was passed through a sand filtration setup and a membrane filtration, with a maximum removal of color above 95%. The results affirmed the positive coagulation properties of M. oleifera, which could serve as a better alternative for chemical coagulant. The optimized treatment conditions derived for the recreated paint effluent were applied in the real paint effluent treatment. An opportunity was identified for re-using treated wastewater, as a cooling fluid and a diluting agent for lower quality paints.The results affirmed the positive coagulation properties of M. oleifera, which could serve as a better alternative for chemical coagulant. Graphical abstract ᅟ.