In-situ microscopy investigation of floc development during coagulation-flocculation with chemical and natural coagulants

Malaysia’s oleochemical processing industry uses crude palm oil as the main source of process feedstocks. Physical–chemical treatment methods such as coagulation and flocculation processes are widely used to pre-treat oleochemical effluent followed by biological treatment to meet Standard A/B as required by the Department of Environment (DOE). Established chemicals that are used include aluminium sulphate and iron chloride as coagulants while the aluminium chloride, iron salts, and polyelectrolytes are used as flocculants. The industry is in constant effort to look into alternative chemicals that are friendly to both human and environment. Natural coagulants such as wheat germ and chitosan are proposed to treat the effluent. The investigations related to the removal rate of turbidity and chemical oxygen demand (COD) between natural and chemical coagulants were carried out. The effluent samples were analysed with the aluminium content. The results showed that the optimum dosage of wheat germ, chitosan, aluminium sulphate and iron chloride were: 2000, 20, 167 and 169 mg/L respectively. The turbidity reduction efficiency percentage using the wheat germ, chitosan, aluminium sulphate and iron chloride were reported at 80.2 ± 30.2, 78.8 ± 32.9, 96.2 ± 2.0 and 90.3 ± 3.9% respectively. The COD reduction efficiency by using wheat germ, chitosan, aluminium sulphate, and iron chloride were reported at 11.4 ± 5.8, 15.7 ± 6.6, 15.7 ± 3.1 and 15.9 ± 3.3% respectively. The findings showed that the effluent samples from natural coagulation process contains of lower aluminium concentration (0.1 ± 0.1 and 0.2 ± 0.1 mg/L) as compared to effluent samples from chemical coagulation process with the aluminium concentration of 2.4 ± 0.4 and 5.5 ± 0.3 mg/L. Thus, the use of wheat germ and chitosan are less hazardous to human health and environment.

An assessment of flocculation was performed by measuring the distribution of the floc size during sedimentation in water works. The size and number of flocs have a greater effect on an evaluation of the efficiency of flocculation rather than the turbidity. The data was collected in situ using particle image velocimetry and image analysis. The measurements were carried out at a water depth of 1m. The removal efficiency of the total organic compounds, UV absorbance and turbidity depended on the size and floc size distribution in flocculation as the G value. The G value of 50 sec-1, 30 sec-1 and 10 sec-1 showed the highest degree of efficiency in the case of an inlet water turbidity of 5 NTU, and the highest degree of efficiency was observed at a G value of 65 sec-1, 40 sec-1 and 10 sec-1 when the inlet water turbidity was 263 NTU. The number of flocs with a distribution of above 1,200㎛ was 14. The dynamics between two important growth mechanisms were investigated as the energy input changed. This is a certain method that makes use of the size and number of flocs as an efficiency assessment.

Leachate is a highly contaminated wastewater which needs to be treated before being discharged to the environment. This is due to the concern that it may cause severe impacts on the environment. One of the well-known treatments that have been adapted for decades for treating leachate is the coagulation and flocculation processes. Coagulation and flocculation processes involve the addition of chemical or natural coagulant in order to destabilize the particles and remove the contaminants present. The rate or performance of chemical/natural coagulant use can be evaluated by determining the sludge settling rate during the flocculation process. This study emphasizes on the effect of Chitosan as natural coagulant aid/polymer in improving the settling rate of flocs after the flocculation process. After a series of experiments, Chitosan as a polymer showed a potential and gave a satisfying results as it improved the sludge settling velocity from 0.57 cm/min, when FeCl3 (chemical coagulant) was used independently to 0.69 cm/min when Chitosan was applied as a coagulant aid. Moreover, Chitosan also increased the floc size to 198. 5 µm compared to 83.3 μm when FeCl3 was used alone. The improvement in terms of settling velocity and size of flocs was due higher molecular weight of Chitosan which provides a long chain for particle attachments. With this ability, Chitosan had a greater potential in increasing the performance of flocculation.

<p>Koagulasi terjadi karena adanya interaksi antara koagulan dengan kontaminan seperti partikel koloid. Proses koagulasi dipengaruhi oleh berbagai faktor, antara lain pH, dosis koagulan, serta kekeruhan larutan. Dalam penelitian ini dilakukan studi untuk mengetahui pengaruh parameter pH dan dosis pada proses koagulasi dan flokulasi dengan menggunakan koagulan aluminum sulfat (Al2(SO4)3..14,3H2O ) dan ferri klorida (FeCl3.6H2O). Air baku yang digunakan adalah suspensi air baku sintetis menggunakan kaolin, dengan variasi suspensi kekeruhan tinggi (124 NTU) dan suspensi kekeruhan sedang (51 NTU). Hasil penelitian mengindikasikan bahwa pengaruh pH dan dosis pada koagulan aluminum sulfat sangat signifikan, sedangkan ferri klorida memberikan rentang pH operasi yang lebih besar dibandingkan dengan aluminum sulfat.<br />Keywords : colloid, destabilization, pH, dosages, sweep flocculation.</p>

Turbidity is one of the importance of physical water quality parameter in the water treatment process. Aluminum sulfate (alum) and ferric chloride are the most widely groups of chemical coagulant and have been extensively used to remove turbidity. However, there are several flaws relates to the environmental issue and impose health risk to the consumer. Fruit peel waste as a natural coagulant is one of the alternative techniques in minimizing the usage of chemical coagulant in water treatment. This research focused on a combination of ratio 60:40 and 80:20 of citrus microcarpa peels and citrus aurantiifolia peels to act as a natural coagulant for turbidity removal. Furthermore, the effect of mixing duration is determined to establish the optimum mixing duration for the highest turbidity removal. Standard practice using jar test were performed in synthetic turbid water using kaolin. The highest turbidity removal occurred at optimum ratio of 80:20 with 77.6% efficiency removal where the optimum mixing duration was found to be at 120 rpm of rapid mixing at 3 minutes, 50 rpm of slow mixing at 20 minutes and 60 minutes of settling time. The study demonstrated that combination of citrus aurantiifolia peels and citrus microcarpa peels have the potential to be used as natural coagulant for a future alternative in water treatment.

Turbidity and natural organic matters (NOMs) cause change in odor, color, and taste of drinking water as well as increasing the concern of bacterial growth in water and wastewater. This article aims to review the coagulation process and to introduce the po tential approaches that can help the water and wastewater authorities to come up with the best coagulant selection. The coagulation is a physicochemical process that is used in the conventional treatment process to reduce turbidity, suspended particles, an d NOMs. Aluminum sulfate (alum) and ferric chloride are the most common coagulants that are used as chemical coagulants. However, there are some health concerns associated with the residual sludge and extra dose of chemical coagulants in treated water and wastewater such as increasing risk of Alzheimer and cancer. Natural Coagulants could be an alternative to reduce the dose of chemical coagulants and residual sludge and consequently reducing the health risks. Natural coagulants are effective in reducing pa rticles, alongside the chemical coagulants or as a stand - alone process. The multidimensional nature of choosing the best process in water and wastewater treatment makes it difficult to select the best coagulant with the minimum health risk. Therefore, we n eed a systematic framework for modeling the coagulation process and selecting cost - efficient coagulant(s) to reduce health risk. Mathematical modeling and health risk assessment are two of the approaches that can be used to select the optimum range and tra ck the residual and found to be helpful for the health risk reduction.

The availability of safe drinking water is very vital issue. In this study four different water plants (surface and ground) were chemically, physically and microbially tested before and after treatment. Surface water was better than ground water regard to their physical and chemical parameters. But the quality of river water is not stable due to suspended particles load caused by land development and high storm runoff during the rainy seasons. Two different coagulants were used for water coagulation and purification: Aluminum sulfate (chemical coagulant) and Moringa oleifera seeds extraction (natural coagulant), and the coagulation process was performed with and without chlorination. M. oleifera was more effective on bacteria of raw water without chlorination than aluminum sulfate. The heterotrophic plate count (HPC) was decreased by 83.6% using Moringa oleifera while with Aluminum sulfate, it decreased by 44.3 %. The total coliform bacteria using Moringa oleifera were decreased by 94.2 % while using aluminum sulfate it decreased by 34.6 %. The fecal coliform bacteria using Moringa oleifera were decreased by 98 % while with aluminum sulfate it decreased by 47.8%. The fecal streptococcus bacteria with using M. oleifera were decreased by 98.7% while using aluminum sulfate it was decreased by 60.6 %. Turbidity of raw water was 13.8 NTU and decreased to 2.2 NTU and 2.1 NTU with Moringa oleifera and aluminum sulfate, respectively. Moringa oleifera seeds extraction is non-toxic and has no side effects like aluminum sulfate and can substitute aluminum sulfate in water treatment.

The aim of this study was to optimize the operational conditions of the coagulation-flocculation process for the clarification of leachate from the landfill Technical Center of Souk-Ahras city. Three coagulants (ferric chloride, aluminum sulfate and ordinary alum) were tested and two types of agitation (mechanical and ultrasound) were implemented. The quality of treatment was assessed via physicochemical and bacteriological analyzes. The parametric study revealed that pH adjustment of leachate was crucial for the success of treatment. The stronger reduction of turbidity was obtained with a coagulant dose of 15%, a stirring speed of 250 rpm and a stirring time of about 5 min for both aluminum sulfate and ordinary alum and 15 min for ferric chloride. An optimum coagulant-to-leachate volume ratio of one was found for the three coagulants, resulting in a turbidity reduction of 99.4%, 98.9% and 98.6% with ferric chloride, aluminum sulfate and ordinary alum, respectively. Bacteriological analyzes highlighted the absence of total germs, fecal coliforms and streptococci for leachates treated with ferric chloride or aluminum sulfate. In contrast, coliforms including 9 total germs, 4 fecal germs and 3 fecal streptococci per 100 mL were detected for leachates treated with ordinary alum. The treatment of leachate was improved by using ultrasound waves with a frequency of 37 kHz and a power of 30 W. Indeed, a significant decrease in the turbidity of supernatants was observed as compared with the use of mechanical agitation, and a value of 0.19 NTU (instead of 0.61 NTU with mechanical agitation) was obtained for a treatment carried out with ferric chloride. The clarification of leachates was optimal at 20°C providing a BOD5 of 100 mg O2/L for both ferric chloride and aluminum sulfate, and 200 mg O2/L for ordinary alum.

This study evaluated the effectiveness of a natural coagulant based on common mallow (Malva sylvestris) to remove turbidity in urban wastewater. A 22 factorial design was selected to determine the optimal dose and the working pH of the natural coagulant. Its potential was studied in 50.0–450 mg/L and 4.00–10.0 ranges of doses and pH, respectively. A simplex lattice mixture evaluated its effectiveness as a coagulant aid combined with aluminum sulfate (conventional coagulant). Mixture proportions 0.000–1.00 were studied for each component, finding the proportion more effective. Results showed that the coagulation treatment could be feasible since a turbidity removal efficiency of 73.7% can be achieved under optimal conditions (50.0 mg/L and pH of 10.0). Likewise, a turbidity removal of 58.9% is obtained using 250 mg/L and maintaining wastewater pH (7.45). This efficiency can be increased using 31.0% natural coagulant mixed with 69.0% aluminum sulfate at 250 mg/L without modifying the wastewater pH. This improvement was associated with the natural coagulant’s high molecular weight and long-chained structure since these properties enhance settling time, floc size and strength, and low sludge production. These results support using common mallow as a natural coagulant, making its use more feasible in alkaline water pH or as a coagulant aid combined with aluminum sulfate for urban wastewater treatment. A cost of USD 370/Kg of natural coagulant was estimated, which is higher than conventional coagulants. However, a cost-effectiveness analysis of its implementation should be performed since process scaling costs could significantly reduce its price.

Phosphorus (P) loading of soils from the repeated application of manure and the associated loss of P to water systems is a serious and increasing problem in today's agricultural landscape. The hypothesis of this study was that the application of mineral amendments to manure might reduce P availability in manure and soil without affecting crop productivity. An incubation experiment was conducted to evaluate the ability of aluminum sulfate, ferric chloride or calcium hydroxide at 100 and 200 g kg−1 of manure to reduce phytoavailable (Mehlich-3 extractable) P in liquid dairy, laying hen and broiler chicken manure. Mehlich-3 extractable P was reduced from 59 to 97% in all manure treated with aluminum sulfate and ferric chloride. The calcium hydroxide treatment resulted in a Mehlich-3 extractable P reduction ranging from −17 to 51%. A container experiment was then carried out to examine the effect of soil with pre-treated manure on timothy (Phelum pretense L.) growth and soil P levels. Timothy yields in all dairy manure treatments were 45–57% lower compared to an N–P–K control, but were not lower compared to the untreated manure control. Dairy manure + aluminum sulfate (200 g kg−1) reduced water-extractable P by 82% relative to the N–P–K control. All other manure and amendment treatment combinations were not statistically different from the N–P–K or the untreated soil controls in terms of water-extractable P, Mehlich-3 extractable P or grass yield. Significant reductions in Mehlich-3 extractable P were observed with the aluminum sulfate or ferric chloride amendments, while varied results were observed with the calcium hydroxide amendment. Results suggest that the use of manure amended with aluminum sulfate or ferric chloride has little effect on growth or P accumulation by timothy. Overall, this study demonstrated that mineral pre-treatment of manure can reduce the extractable P content of the manure and soil without negative effects on plant growth.

Extensive studies have been conducted to discover natural, efficient and cost-saving coagulants for water treatment. Meanwhile, chemical coagulants are being used conventionally in drinking water treatment. This study investigates the efficacy of diatomite as a natural coagulant in river water treatment. First, synthetic turbid water was used to validate the coagulant efficiency. Then, coagulation and flocculation behaviors were studied by using the river water samples from Langat River and Semenyih River. Turbidity removal efficiency of synthetic turbid water revealed that a low dosage of 3.5 mg/L could reach turbidity reduction of 83.46%. The turbidity reduction for Semenyih River water with initial turbidity of 31.8 NTU was achieved at 91.7% with 18 mg/L dosage at pH of 7.4 whereby, for Langat River water with an initial turbidity of 43.3 NTU, the turbidity reduction was achieved at 94.5% with a dosage of 26 mg/L at pH of 8.0. These results showed that water turbidity removal was influenced by both high and low natural organic material. This is because the best dosage of coagulant is indirectly proportional to the molar mass of natural organic material. In conclusion, diatomite is a promising material to be used as a natural coagulant in water treatment applications. Â

Wastewater generated by the industry manufacturing detergents and various kinds of consumer products normally contains very high contents of mixed surfactants, organic matters expressed as chemical oxygen demand (COD), and phosphates that must be treated prior to discharge to the aquatic environment. In this study, jar-test experiments were conducted to evaluate the waste activated sludge (WAS) as a coagulation aid in the coagulation-flocculation process with ferric chloride or aluminum sulfate as a coagulant for the treatment of wastewater collected from the aforementioned industry. The WAS was selected because of its adsorption capability of anionic surfactants and its availability from the wastage stream of biological wastewater treatment process. The effective dosages of both coagulants with and without the WAS additions were determined in this study. Without the WAS addition, the concentrations of 800 mg/L aluminum sulfate at the optimum pH value of 8 and 2208 mg/L ferric chloride at the optimum pH value of 12 were the optimum chemical dosages. It appears that aluminum sulfate was more effective than ferric chloride based on the chemical dosage and removal efficiency. The turbidity, suspended particles, anionic surfactants, COD, and phosphates removal efficiencies of aluminum sulfate and ferric chloride under the optimum dosage were 95.6, 88.2, 78.4, 73.5, 47.3% and 98.8, 92.0, 72.7, 67.5, 53.1%, respectively. The addition of 200 mg/L WAS was sufficient to reduce the optimum dosages of both chemicals by 200 mg/L. The cationic surfactant existing in the wastewater worked as a flocculating agent leading to the flocculation of waste activated sludge resulting in the enmeshment of the suspended particles and colloids on which the COD, anionic surfactants, and phosphates were adsorbed. However, the substances removal efficiencies of ferric chloride and aluminum sulfate were slightly enhanced and reduced, respectively. It is possibly explained that the settling time is insufficient to settle the aluminum hydroxide floc when it is compared to the ferric hydroxide floc because the iron floc is normally heavier than the alum floc.

Turbidity removal from aqueous environments by Pistacia atlantica (Baneh) seed extract as a natural organic coagulant aid

Water is an essential element for human survival, yet many individuals still lack access to treated water to meet their basic needs. To mitigate this situation, alternative water treatment technologies that are accessible and easy to handle are being explored. Among these, the use of Moringa oleifera seeds as a natural coagulant and the application of a helically coiled tube as a flocculation unit have been studied. In this context, this study aimed to evaluate the turbidity removal efficiency using two different coagulants (Moringa oleifera and aluminum sulfate) in an alternative water clarification system. The system consists of a helically coiled tube flocculator (HCTF) coupled with a conventional decantation unit. It was observed that the coagulant solution from shelled seeds required a lower dosage to achieve efficiencies above 90% compared to the coagulant solution from seeds with shells. The optimal dosage was 30 mL/L of the coagulant solution from shelled seeds. This dosage resulted in high turbidity-removal efficiencies, ranging from 92% to 100%. The processing method of the seeds that yielded the highest efficiency in turbidity removal was the mortar and pestle, as opposed to a blender. The optimal configuration of the alternative water clarification system comprised using the lower HCTF in a horizontal orientation. The use of the alternative water clarification system, along with the natural coagulant, proves to be a promising alternative clean technology for water clarification in locations without access to conventional treatment, being efficient in turbidity removal.

In this research, a plant material (Strychnos potatorum seed powder) has been used as natural coagulants, and tested the ability to remove turbidity from synthetic water and industrial water samples. The results from industrial water samples were compared with synthetic water samples. Experiments have been conducted in the laboratory to assess the percentage (maximum) of turbidity removal at various levels (i.e., 50, 80, 110, 120, and 145 NTU) from collected and prepared samples. Parameters influencing the coagulation mechanism such as dosage and pH were reported most suitable parameters for maximum turbidity removal. In this regard, the percentage of turbidity removal varies between 46–78% and 50–84% for synthetic and industrial water samples, at an ideal pH level (6–7) respectively. In addition, the isotherm model (i.e., Langmuir and Freundlich) was used to assess the sorption analysis from experimental data sets, wherein the monolayer sorption of contaminants onto the seed powder of S. potatorum was detected. The outcomes highlighted the effect of sorption in the turbidity removal percentage from both synthetic and industrial water samples, advocating the use of S. potatorum as a cost-effective alternative for industrial wastewater treatment.