Behavior of turbidity, pH, alkalinity and color in Sinú River raw water treated by natural coagulants

Abstract

Natural coagulants were evaluated in saline Hylocereus cf. trigonus stems, gum exudate of Albizia saman, bark and seeds of Moringa oleifera and bark of Guazuma ulmifolia in raw water samples from the Sinú river with 56, 104, 200 and 301 Nephelometric Turbidity Units, and Jar tests were conducted to determine the performance removal turbidity of each coagulant, with doses between 5 mg/L to 60 mg/L. pH, color and alkalinity of the water samples were measured before and after treatment to verify the incidence of the coagulant in the purification process. For H. trigons, A. saman, G. ulmifolia and bark of M. oleifera, removal percentages ranged between 50% and 70% and up to 95% for M. oleifera seed. Greater coagulant activity was recorded for applied doses between 20 mg/L to 30 mg/L, independent of raw water turbidity. The pH and total alkalinity had no significant changes for the entire dose range, while the true color slightly increased with extracts of H. trigons, A. saman, G. ulmifolia and bark of M. oleifera, and decreased significantly with M. oleifera seeds to values lower than 5 CU, which was the extract with the highest in removing turbidity and color. RESUMEN:Se evaluaron coagulantes naturales en solución salina de tallos de Hylocereus cf. trigonus, exudado gomoso de Albizia saman, corteza y semilla de Moringa oleífera y corteza de Guazuma ulmifolia, en muestras de agua cruda del río Sinú, con turbidez de 56, 104, 200 y 301 UNT y se realizaron ensayos de jarras para determinar la remoción de turbidez de cada coagulante, con dosis de 5 mg/L a 60 mg/L. Se midió el pH, la alcalinidad y el color de las muestras de agua, antes y después del tratamiento, para verificar la incidencia de los coagulantes en el proceso de potabilización. Los porcentajes de remoción variaron entre el 50% y 70% para H. trigons, A. saman, G. ulmifolia y corteza de M. oleífera y hasta del 95% con semilla de M. oleífera. Para las dosis aplicadas entre 20 mg/L a 30 mg/L se registró mayor actividad coagulante, independiente de la turbidez del agua cruda. El pH y la alcalinidad total no tuvieron variaciones significativas para todo el rango de dosis, mientras que el color verdadero aumentó levemente con los extractos de H. trigons, A. saman, G. ulmifolia y corteza de M. oleífera y disminuyó significativamente con la semilla de M. oleífera hasta valores menores a 5 UC, siendo este el extracto de mayor eficiencia en la remoción de turbidez y color.

Use of Cactus Opuntia as a Natural Coagulant: Water Treatment in Developing Countries.

“…The first driver entails the demerits associated with conventional chemical coagulants, which create an opportunity for consideration of their plant-based counterparts. Summing the demerits across the studies reviewed indicates that chemical coagulants are ineffective at low water temperatures, significantly alter water pH, decrease transmission capacity, and cause corrosion problems, besides causing environmental and sustainable development concerns such as costliness, detriments to human health, non-biodegradability, and production of large sludge volumes (Yin, 2010;Feria-Diaz et al, 2016;Vijayaraghavan et al, 2011). The number and significance of disadvantages associated with synthetic chemical coagulants, especially considering the need for environmentally conscious and sustainable water treatment approaches in today's world, therefore have been a driving factor behind the emerging consideration of plant-based coagulants for use in water treatment.…”

“…The studies reviewed altogether indicate that plant-based coagulants are advantageous in aspects such as safety for human health, biodegradability, low cost acquisition, low-level sludge production, effectiveness in treating water, and no significant alteration pH of treated water (Yin, 2010;Feria-Diaz et al, 2016;Vijayaraghavan et al, 2011). Notably, most of the aforementioned merits indicate that plant-based coagulants such as cactus align with local, national, and global objectives in environmental protection and sustainable development.…”

Use of Seawater and Moringa Oleifera Seeds for Turbidity Removal in Water Treatment

“…Moringa oleifera seeds were dried outdoors for 12 hours, then ground in an industrial mill and screened in a mesh No. 30 (0.60mm) according to the Tyler series, until reaching a fine powder [9], [12]. Later, 30.0g of Moringa oleifera seed powder was dissolved in three 1.0-liter volumetric flasks (10g per flask) with distilled water, 1.0% sodium chloride saline solution (w/v) and seawater (w/v), respectively.…”

“…Filtrates were labeled as coagulant extract in distilled water, saline solution with a concentration of 10,000 mg/L and solution in seawater. Solutions were kept refrigerated at 4°C until application [12].…”

“…Recent studies have shown that Moringa oleifera seed powder can reduce low and high turbidity values in surface waters [6] - [9]. Generally, natural coagulants are biodegradable, and their use is possible in developing countries, since they can be grown locally and have a wide effective dosage range for treatment of different colloidal suspensions in raw waters [10] without significantly altering pH and alkalinity of samples after coagulation [9], [11], [12]. Even, recent studies consider that coagulant extracts of M. oleifera can be a suitable alternative for partial replacement of aluminum sulfate in the raw water treatment of slow bodies such as swamps or reservoirs [13].…”