Use of Natural Coagulants in Removing Organic Matter, Turbidity and Fecal Bacteria from Hospital Wastewater by Coagulation-Flocculation Process

Hospital wastewater represents an infectious and toxic risk to human health and the environment due to its contents. Most hospitals in developing countries, including Benin, do not have a wastewater treatment plant. In this study, the wastewater from two hospitals in northern Benin was characterized and then treated with Azadirachta indica leaves, Moringa oleifera and Luffa cylindrica seeds by coagulation/flocculation process. The wastewater characteristics showed that the collected samples are greatly polluted by organic matter and fecal bacteria such as Escherichia coli, Enterococcus fecal and Total coliforms. Jar-test results revealed that 95.74%, 78%, 49.19% of turbidity, 51.35%, 38.32%, 22.19% of COD, 93.16%, 85.26%, 83.30% against Escherichia coli, 92.11%, 90.93%, 94.60% against total Coliforms and 99.37%, 91%, 99%, 55.07% against Enterococcus were removed from hospital wastewater using Moringa oleifera, Luffa cylindrica seed and Azadirachta indica leaves respectively at dose of 100 mg/L. The results highlighted that the natural coagulants could be successfully used for the removal of turbidity and fecal bacteria from hospital wastewater.

Effectiveness of Using Natural Materials as a Coagulant for Reduction of Water Turbidity in Water Treatment

Coagulation-Flocculation plays a significant role in drinking water treatment. Laboratory experiments were carried out in order to assess the effectiveness of using Conocarpus Leaves Solution (CLS) as a natural coagulant in conjunction with the synthetic chemical represented by Alum in the water purification. Biological test was carried out to confirm that these leaves are not toxic, followed by optimizing the dosage of alum and then Alum and CLS were applied to the turbid water whose turbidity level has two ranges, (20 - 35) NTU and (90 - 120) NTU, using the JAR Test. The parameters determined before and after coagulation were turbidity, pH and temperature. The experiments showed that the optimum dose of alum coagulant (individually) for high turbid water is about 18 mg/l with PH = 7 and 24 mg/l f with PH = 5 and 9. In addition, for the low turbidity water, the optimum dose of alum was lower than in the high turbid water. In terms of using Alum in conjunction with CLS, at high range of turbidity, the results show that at 33% ratio of leaves solution to alum coagulant, there are 50% and 75% turbidity reduction performed for the PH equal to 5 and 9 respectively. Although about 62% and 65% turbidity reduction were achieved at PH = 7 and PH = 9 in the low range level. However, low reduction in turbidity has occurred when the water PH = 5. The amount of leaves solution added to the water in the water treatment plant is highly important, hence it decreases the amount of using the synthetic chemicals by about 33% of the quantity that required for water treatment and that will help both, the water industry and the human health. More studies need to be achieved in particular different concentration of the Conocarpus leaves solution in order to improve the percentage of using the natural material as a coagulant.

Evaluation of the Opuntia dillenii as Natural Coagulant in Water Clarification:Case of Treatment of Highly Turbid Surface Water

This study was performed in laboratory scale and consisted of the using of aqueous Opuntia dillenii solution for the clarification of very turbid surface water (Turbidities varying between 186 NTU and 418 NTU). This plant from Cactaceae family was used as a natural coagulant for the different clarification tests. The preliminary phytochemical Screening of the powder of this plant showed that it contains tanins, saponins and mucilages. Flocculation and coagulation tests showed that Opuntia dillenii can be used in highly turbid water treatment. The removal efficiency varied from 89% to 93% for the turbidity and suspended solids, and from 4% to 15% for the obvious color in water when we used the optimum values of this natural coagulant (1 mL to 10 mL). The successive addition of this natural coagulant and the lime, gave a better elimination of turbidity and suspended solids, and a good reduction for the color. The removal efficiency of the turbidity and suspended solids became more than 95% and the one of the color between 67% and 94%.

Comparison of different combined treatment processes to address the source water with high concentration of natural organic matter during snowmelt period

The source water in one forest region of the Northeast China had very high natural organic matter（NOM） concentration and heavy color during snowmelt period. The efficiency of five combined treatment processes was compared to address the high concentration of NOM and the mechanisms were also analyzed. Conventional treatment can hardly remove dissolved organic carbon（DOC） in the source water. KMn O4pre-oxidization could improve the DOC removal to 22.0%. Post activated carbon adsorption improved the DOC removal of conventional treatment to 28.8%. The non-sufficient NOM removal could be attributed to the dominance of large molecular weight organic matters in raw water, which cannot be adsorbed by the micropore upon activated carbon. O3＋ activated carbon treatment are another available technology for eliminating the color and UV254 in water. However, its performance of DOC removal was only 36.4%, which could not satisfy the requirement for organic matter. The limited ozone dosage is not sufficient to mineralize the high concentration of NOM. Magnetic ion-exchange resin combined with conventional treatment could remove 96.2%of color, 96.0% of UV254 and 87.1% of DOC, enabling effluents to meet the drinking water quality standard. The high removal efficiency could be explained by the negative charge on the surface of NOM which benefits the static adsorption of NOM on the anion exchange resin. The results indicated that magnetic ion-exchange resin combined with conventional treatment is the best available technology to remove high concentration of NOM.