Polyaluminum Chloride Coagulation Research Articles

NOM removal and residual Al minimization by enhanced coagulation: roles of sequence dosing with PACl–FeCl3

Abstract To remove higher proportions of natural organic matter (NOM) in water treatment plants, over dosing of Al-based coagulant is frequently applied. However, this leads to the risk of an excess of coagulant residue in the clean water. In this study, sequential coagulation with polyaluminum chloride (PACl) and FeCl3 was proposed to improve the removal of NOM as well as to minimize residual Al. Single dosing with either PACl or FeCl3 in particular was compared with sequential coagulation, with different dosing sequences of PACl–FeCl3 (P–F) or FeCl3–PACl (F–P). At optimum dosage, sequential coagulation P–F showed twice as much dissolved organic carbon (DOC) removal from water containing algogenic organic matter, compared to single dosing of PACl and sequential coagulation F–P. However, sequential coagulation F–P was the most effective approach for humic substance removal that improved DOC removal up to >70% compared to other dosing approaches (<60%). Practical treatment with real water also showed the advantages of sequential coagulation with P–F in improving the removal of low SUVA NOM by 18% compared to the traditional single dosing of PACl. As expected, the Al residues found in both sequential coagulation (0.07 mg/L) were significantly reduced compared to single dosing with PACl (0.15 mg/L), indicating the promising application of sequential coagulation for future safe water treatment.

Sulfate ion in raw water affects performance of high-basicity PACl coagulants produced by Al(OH)3 dissolution and base-titration: Removal of SPAC particles by coagulation-flocculation, sedimentation, and sand filtration

Many PACl (poly-aluminum chloride) coagulants with different characteristics have been trial-produced in laboratories and commercially produced, but the selection of a proper PACl still requires empirical information and field testing. Even PACls with the same property sometimes show different coagulation performances. In this study, we compared PACls produced by AlCl3-titration and Al(OH)3-dissolution on their performance during coagulation-flocculation, sedimentation, and sand filtration (CSF) processes. The removal targets were particles of superfine powdered activated carbon (SPAC), which are used for efficient adsorptive removal of micropollutants, but strict removal of SPAC is required because of the high risk of their leakage after CSF. PACls of high-basicity produced by AlCl3-titration and Al(OH)3-dissolution were the same in terms of the ferron assay and colloid charge, but their performance in CSF were completely different. High-basicity Al(OH)3-dissolution PACls formed large floc particles and yielded very few remaining SPAC particles in the filtrate, whereas high-basicity AlCl3-titration PACls did not form large floc particles. High-basicity PACls produced by Al(OH)3-dissolution were superior to low-basicity PACl in lowering remaining SPAC particles by the same method because of their high charge neutralization capacity, although their floc formation ability was similar or slightly inferior. However, high-basicity Al(OH)3-dissolution PACl was inferior when the sulfate ion concentration in the raw water was low. Sulfate ions were required in the raw water for high-basicity PACls to be effective in floc formation. In particular, very high sulfate concentrations were required for high-basicity AlCl3-titration PACls. The rate of hydrolysis, which is related to the polymerization of aluminum species, is a key property, besides charge neutralization capacity, for proper coagulation, including formation of large floc particles. The aluminum species in the high-basicity PACls, in particular that produced by AlCl3-titration, was resistant to hydrolysis, but sulfate ions in raw water accelerated the rate of hydrolysis and thereby facilitated floc formation. Normal-basicity Al(OH)3-dissolution PACl was hydrolysis-prone, even without sulfate ions. Aluminum species in the high-basicity AlCl3-titration PACl were mostly those with a molecular weight (MW) of 1–10 kDa, whereas those of high-basicity Al(OH)3-dissolution PACls were mostly characterized by a MW > 10 kDa. Normal-basicity Al(OH)3-dissolution PACl was the least polymerized and contained monomeric species.

Characterization of textile dyeing effluent and its treatment using polyaluminum chloride

The study aimed to expose the level of pollution owing to textile dyeing effluents and assess the coagulant efficiency of polyaluminum chloride (PAC) for treating the textile dyeing effluents. The discharged of untreated textile dyeing effluents have severely polluted water and soils, threatened the entire environment. The study analyzed the discharged and treated effluents using standard methods of analysis. The optimized parameters of the coagulant PAC were the dose, contact time, temperature, and agitation speed. The color removal efficiency study observed that the coagulant PAC removed the color from 85 to 95% of three dyeing effluents at optimum conditions. The result showed that the maximum reduction of EC, TDS, TSS, COD, BOD, Cl−, HCO3− and SO42− were found to be 83.66, 85.7, 82.05, 82.05, 83.45, 66.91, 66.91 and 72.88%, respectively. It also showed that the coagulant efficiently reduced heavy metals and the highest percentage of reduction achieved was 72.7 and 98.52 for Fe and Pb, respectively, from the effluents. Hence, the PAC would be a potential coagulant for treating the textile dyeing effluents that help to build a sustainable environment.

Photocatalysis-coagulation to control ultrafiltration membrane fouling caused by natural organic matter

Various pretreatments of raw surface water before ultrafiltration (UF) to retard membrane fouling due to natural organic matter (NOM) were compared in this study. Water treatment by conventional coagulation, visible light irradiation with the presence of a novel photocatalyst of Bi2O3–TiO2 supported onto powder activated carbon (Bi–Ti/PAC), and their combination were compared in terms of removal of NOM and the optimal conditions were determined. The composite nano-photocatalyst of Bi–Ti/PAC could function as a pre-oxidant and a flocculation core assisting coagulation. Experiments results show that 58% of the NOM present could be removed by quantization of dissolved organic carbon in the combination treatment under optimal conditions of 2.0 g/L of photocatalyst dosage with light exposure of 20 min and 0.04 mmol polyaluminium chloride coagulant dosage with a solution pH of 7. The combined pretreatment with UF produced a reduction of 88% in total membrane fouling, with reversible and irreversible fouling being significantly decreased because of the removal of hydrophilic, protein- and humic-like substances, along with degradation and removing of medium-molecular weight (MW) and high-MW compounds into smaller molecules. Models used to fit the generated data indicated that the provided combined pretreatment had largely reduced standard blocking of the membrane pores. The effectiveness of the pretreatment was confirmed by characterization of the hydraulic irreversible organic foulants. This work demonstrated the potential advantages of combining photocatalysis with coagulation as a pretreatment of raw surface water and subsequent UF in simultaneously controlling membrane fouling and improving the permeate quality.

Effect of in-situ formed Al hydrates through long-term aging on enhanced particle destabilization by PACl coagulation

Aging of polyaluminum chloride (PACl) coagulants could significantly influence hydrolyzed Al speciation ruling coagulation performance. The goal of this study was to investigate Al species transformation through long-term aging and its impact on coagulation performance. Two kinds of commercial coagulants (PACl-1 and PACl-2) were stored for in-situ aging tests in six months to evaluate Al species variation with time and the performance of coagulation with natural turbid waters. The results showed that CaSO4 precipitation easily occur in a commercial PACl coagulant with time as it contains SO42− and Ca2+. It also activates the precipitation of gibbsite Al(OH)3 in PACl with aging. Through 180 days aging, both monomeric Al (Ala) and polymeric Al (Alb) substantially transform into colloidal Al (Alc) and precipitated for both PACl coagulants. At low turbidity (10 NTU), PACl-1 has a superior turbidity reduction rate than PACl-2, while PACl-2 performs a little better turbidity reduction at high turbidity (1000 NTU) regardless of aging time. With aging time, an obvious decrease in turbidity reduction for PACl-1 coagulation is observed at low turbidity of 10 NTU, while the improvement in turbidity reduction for PACl-2 coagulation by enhanced sweep flocculation can be achieved as Alb mostly transform into Alc after 150 days aging. It is concluded that dominant in-situ formed Alc after a long time hydrolysis can improve PACl coagulation efficiency in turbidity reduction by enhanced sweep flocculation, especially for low turbidity water, but the increase in preformed Alc in PACl would worsen particle destabilization after aging.

The Application of Nanofiltration Membrane for Palm Oil Mill Effluent Treatment by Adding Polyaluminium Chloride (PAC) as Coagulant

The rapid development of Crude Palm Oil (CPO) production has led to an increase in the production of Palm Oil Mill Effluent (POME) as well. POME will cause problems in the environment because contains high contaminants. This study aims to investigate the effect of the coagulant Polyaluminium Chloride (PAC) variations and the membrane’s operating pressure on the POME treatment process using the nanofiltration membrane (NF) with the coagulation-flocculation process as pre-treatment. The PAC was used in the coagulation-flocculation process with variations in concentration (5.0; 5.5; 6.0; 6.5; 7.0 g/L). The process was completed by a rapid stirring of 200 rpm for 5 minutes, followed with slow stirring at 60 rpm for 15 minutes and settling time for 30 minutes. The process of membrane nanofiltration was carried out for 60 minutes with variations in operating pressure (8.0; 9.0; and 10 bars). In each treatment process, effluent quality testing was carried out with Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS) and oil/fat as parameters. In addition, an analysis of permeate fluxes and rejection of NF membrane was also carried out. The results of the analysis suggested that the best coagulant doses are 6.0 g/L with the reduction percentage of BOD, COD, TSS and oil/fat at 78.85%; 68.57%; 92.77% and 92.31% respectively. The highest percentage of NF membrane rejection was found at a pressure of 10 bar, which is equal to 94.71%; 94.86%; 97.92% and 95% respectively for BOD, COD, TSS and oil/fat with a flux value of 7.16 L/m2.hours.

Irreversible fouling in hollow-fiber PVDF MF/UF membranes filtering surface water: Effects of precoagulation and identification of the foulant

In this study, microfiltration (MF) and ultrafiltration (UF) of surface water were compared in terms of irreversible fouling and effective pretreatment. Hollow-fiber MF/UF membranes made from the same polymer (polyvinylidene fluoride (PVDF)) were examined with multiple samples of surface water used for drinking water production. Experiments were carried out in a realistic style: with a constant flow rate and periodic backwashing. Regardless of the source of the feed water, evolution of fouling was less significant in the case of UF. In the case of MF, anion exchange followed by coagulation using poly-aluminium chloride (PACl) efficiently mitigated membrane fouling, whereas PACl coagulation alone was sufficient for UF. Artificial alteration of the composition of natural organic matter (NOM) in the feed water was carried out by MF/UF with different pore sizes, and it was revealed that different fractions of NOM were responsible for evolution of irreversible fouling in MF and UF: large biopolymers and small biopolymers were responsible for irreversible fouling in MF and UF, respectively. The mechanism of fouling mitigation by coagulation was also investigated. Cake (coagulated flocs) deposited on the membrane surface mitigated irreversible fouling in UF, whereas it did not affect irreversible fouling in MF. It was postulated that advection flow caused by membrane filtration made more adsorption sites available inside the flocs for removal of small biopolymers (i.e., UF foulants).

Pretreatment for seawater desalination plants by calcite ooids filter

The calcium carbonate is the main constituent of calcite ooids which are important and often dominant components of marine sediments. In this study, the calcite ooids were fabricated inside a semi-pilot seawater-softening unit assembled in the Egyptian Petroleum Research Institute (EPRI) with an effective particle sizes varying from less than 0.5 up to 3.0 mm. The created calcite ooids were used as new filtration media in pretreatment stage of a seawater desalination plant. A feed water quality improvement was achieved at various temperatures (20–40 °C) and at various speeds (20–60 l/min). Typical operating qualifications of calcite ooids filter in seawater desalination plant are speed of 20 l/min and temperature of 40 °C in the presence of poly-aluminum chloride coagulant, PAC (1.6 mg Al/l). The filtrate produced from ooids filter had a better silt density index (SDI) of 2.85, higher removal of turbidity (89.4%), higher total organic carbons reduction (66.1%) and TOC reduction exceeds to 95.7% after granular activated carbon filter. Therefore, the service and backwash flow rates and bed expansion percentage are the essential operating parameters which were studied.

Understanding the Efficiency of Aluminum Coagulants Used in Dissolved Air Flotation (DAF)

This paper reports on the efficiency of five aluminum coagulants for the treatment of a paper mill wastewater by dissolved air flotation (DAF). The coagulants studied were: alum, a polyaluminum chloride coagulant of high aluminum content and intermediate basicity (PAC-MB), another with intermediate aluminum content and high basicity (PAC-HB), a polyaluminum nitrate sulfate of intermediate aluminum content and basicity (PANS) and one hybrid coagulant formed by the combination of PANS and a mixture of polyamines (PANS-PA). The influence of Al speciation on contaminants removal and the main flocculation mechanisms involved have been analyzed. High removal of suspended solids together with significant removal of dissolved and colloidal material (COD and silica) were obtained, which is required for extended reuse of this process water. PAC-HB was the best product for removing suspended solids (85%) and soluble silica (50%) with a rather limited COD removal (5%), while PANS-PA obtained high turbidity (90%) and silica removal (45%) together with a significant soluble COD removal (15%). Monomeric Al (Ala, Alm) was more efficient in removing suspended solids and soluble COD than polymeric or colloidal Al (Alc, Alu), but the latter was more efficient in removing soluble silica. Results demonstrated that the main flocculation mechanism varies with the aluminum dosage, being predominantly charge neutralization at low dosages and sweep flocculation at high dosages. The floc strength factor however, was very high and similar for all the coagulants and dosages tested (85–90%), as it was mainly determined by the behavior of the pre-flocculated suspended solids present in wastewater. The reflocculation factor varied from 45 to 75% at the lowest dosages to almost zero at the highest dosages, confirming the transition from charge neutralization to sweep flocculation. The flocs formed by PANS-PA had lower strength than the others and it decreased with the dosage while its reflocculation factor was almost zero, even at low dosages. Due to the polyamines present in this coagulant, its flocculation mechanism is through both charge neutralization and patch formation, especially at low dosages, and sweep flocculation and interparticle bridge formation at high dosages.

Discussion on the electrical neutralization ability of polyaluminum chloride (PACl) coagulants with different OH/Al3+ values by fluorescence quenching effect

Discussion on the electrical neutralization ability of polyaluminum chloride (PACl) coagulants with different OH/Al3+ values by fluorescence quenching effect

Performances and mechanisms of sludge dewatering by a biopolymer from piggery wastewater and application of the dewatered sludge in remediation of Cr(VI)-contaminated soil

In this study, a biopolymer was harvested from piggery wastewater to treat biological sludge. Effectiveness of the combination of polyaluminum chloride (PAC) and this biopolymer in sludge dewatering was investigated and the dewatering mechanism was discussed. Results showed that as high as 3.11 g of biopolymer can be harvested from 1 L of piggery wastewater by cultivating Bacillus megaterium. After treated by PAC with a dosage of 1.5 g/L at pH point of 7.5, specific resistance to filtration (SRF), moisture content (MC), settled volume after 30 min (SV30) and capillary suction time (CST) of the sludge were decreased to 3.4 × 1012 m/kg, 84.5%, 79.8% and 65 s, respectively, and dry solid (DS) was increased to 21.4%, indicated that sludge dewatering was obviously enhanced by PAC. After further treated by 2 g/L of the biopolymer, SRF, MC, SV30 and CST were further decreased to 2.1 × 1012 m/kg, 59.8%, 55.6% and 39 s, respectively, and DS was increased to 28.6%, indicated that sludge dewatering was further enhanced by the biopolymer. For the enhancing mechanism, on the one hand, the extracellular polymeric substances (EPS) was significantly disintegrated to release binding bound water, which was facilitating sludge dewatering; on the other hand, the synergistic effect of PAC coagulation and biopolymer flocculation, including charge neutralization and bridge-aggregation, were favorable to sludge dewatering. Additionally, we found that the dewatered sludge was helpful for remediation of chromium (Cr)(VI)-contaminated soil by raising soil pH and decreasing bioavailability of Cr(VI) in the soil, after remediated by 75 g/kg of the dewatered sludge for 60 days, the soil pH was increased from its initial value of 4.32–8.52, and the residue Cr(VI) in the soil extract was appeared as 2.2 mg/L.

Study of coagulant effective dose for water treatment plant in Semarang City

Water is an important component which community need, especially for clean water consumption. Water treatment plant is one of the solutions as fulfilment of clean water needs that guaranteed quality, quantity and continuity. Determination of the effectiveness of the type of coagulant is used to guarantee the quality of raw water according to the requirements of water quality of drinking of health minister of Republic Indonesia 492/2010 law. Blorong River is one of the water sources in Semarang City which has characteristics of turbidity of 41.1 NTU; pH 7.11 and TSS 110 mg/L. The aim of this study is to determinate effective type and dose from several coagulants. The method uses the Jar Test method with a variety of velocity gradients. The first variation is 550/sec and 100/sec, the second variation is 650/sec and 80/sec, and a third variation 700/sec and 60/sec. The types of coagulants used are Poly Aluminium Chloride (PAC), Aluminium Sulphate and Chemical Mixing Alum with parameters observed are turbidity, pH, total suspended solids (TSS), and flock size. This study resulted coagulant PAC as an effective coagulant with an optimal dose of 10 ppm resulting in a pH of 6.71, turbidity 1.65 NTU, TSS 34 mg/L and flock size 1.7 cm at the third velocity gradient. Based on the planning discharge of 200 L/sec, the PAC coagulant costs IDR100,000 L/day.

Semi-solid rheology characterization of sludge conditioned with inorganic coagulants.

Rheology measurement, a state-of-the-art technology in a multitude of engineering disciplines, has often been used for computational fluid dynamic simulation of wastewater treatment processes, especially in anaerobic digestion and dewatering. In this work, rheological tests were used to study the semi-solid characteristics of sludge and a good result was obtained. The inorganic coagulants polyaluminum chloride (PAC) and ferric chloride (FC) both increased the floc strength of sludge, leading to higher rheology parameters such as elastic modulus, viscous modulus and specific thixotropy area. Curiously, the shape of all rheological curves exhibited little change with increasing coagulant dosage. The results indicated that various physical and chemical actions among coagulants and sludge flocs relate only to rigid structure, not to the nature of rheology behavior. Frequency sweep tests clearly showed that elastic modulus was a logarithmic function of frequency, suggesting that sludge could not properly be called a soft material due to its inorganic particles. An improved viscoelastic model was successfully developed to predict the experimental data of creep and recovery tests in the linear viscoelastic region. Furthermore, complicated viscoelastic behavior of sludge was also observed, and all the rheology tests could provide the optimum dosage of PAC but not the optimum dosage of FC.

OPTIMIZATION OF THE ALUMINUM SULFATE AND PAC (POLY ALUMINUM CHLORIDE) COAGULANT ON TELLO RIVER WATER TREATMENT

Abstract- Tello River water used by PT. PLN SULTANBATARA for sanitation and process water. One of the process's water is boiler feed water. River water has fluctuative characteristics depending on the season that occurs such as turbidity and Total Suspended Solid (TSS). The presence of TSS in boiler feed water needs to be minimized as it can decrease boiler performance in generating heat. The concentration of TSS in river water can be removed by coagulation and flocculation method with the addition of coagulant. Excessive coagulant distribution will increase the concentration of dissolved solids (TDS) of water. Thus, it is necessary to determine the optimum concentration of coagulant based on initial TSS concentration of river water. The objective of this research is to determine the optimum concentration of Aluminum Sulfate (Al2(SO4)3) and PAC (Poly Aluminum Chloride) Coagulant in reducing TSS water of Tello River. The sample used in this research is Tello river water which has an initial TSS concentration of 150 mg/L. The coagulant used was Aluminum Sulfate and PAC with several concentration variation of 5% - 40% to the initial TSS concentration of river water. Analysis of TSS content of samples using Gravimetry method. The optimum concentration of coagulant Aluminum Sulfate and PAC was 35% and 25% to the initial TSS concentration of river water where the final concentration of TSS obtained was 20 mg/L and 15.5 mg/L with percent TSS removal of 86.67% and 89.6 %. Keywords: Total Suspended Solid, Coagulation, Aluminium Sulfate, Poly Aluminium Chloride (PAC)

Floc properties and membrane fouling in coagulation/ultrafiltration process for the treatment of Xiaoqing River: The role of polymeric aluminum-polymer dual-coagulants.

In this study, novel lignin-based flocculant (LBF) was prepared in recycling of papermaking sludge. And LBF combined with polyaluminum chloride (PAC) was used in the coagulation/ultrafiltration combined process. Effects of polymer types, pH and ultrafiltration time on the membrane fouling mechanism and resistance distribution were studied based on blocking model and resistance-in-series model. Results showed that strongly-attached external fouling was the primary fouling mechanism in PAC coagulation and dual-coagulation systems. Dual-coagulation achieved the slighter fouling due to the formation of poriferous cake layer. In the PAC system, the fouling mechanism transformed from intermediate fouling to cake layer with the ultrafiltration process. Addition of LBF could accelerate cake layer formation and further control internal fouling. PAC+LBF mainly decreased external fouling resistance and reversible internal fouling resistance to enhance permeation flux. And the total resistance (expect intrinsic membrane resistance) was lowered by more than 50% compared with PAC. The primary combined models in PAC and PAC+LBF systems were cake-standard blocking and cake-intermediate blocking, respectively. Initial pH showed a significant effect on membrane fouling. The slighter membrane fouling was acquired at pH 5.5. Addition of LBF could decrease the influence of pH on the fouling index and distribution.

Membrane fouling by alginate in polyaluminum chloride (PACl) coagulation/microfiltration process: Molecular insights

While polyaluminum chloride (PACl) coagulation- microfiltration (MF) process is one of the most popular methods for surface water treatment, the fouling mechanism underlying this process has not well explored. In this study, sodium alginate (SA) was used as the model organic matter. It was interestingly found that, specific filtration resistance (SFR) of alginate-aluminum complexes initially increased to an ultra-high value of 1.40 × 1015 m−1 kg−1, and then sharply declined to rather low level of 3.85 × 1012 m−1 kg−1 with the increase in PACl dosage from 0 to 500 mg/L. A series of characterizations of the foulant samples showed that the alginate-aluminum complexes suffered a morphology transition from gel form to floc/cake form with the PACl dosage increase. Density functional theory (DFT) calculation indicated the preferential coordination of aluminum ions with the terminal carboxyl groups of the alginate chains at low PACl level, facilitating homogeneous gel formation. The ultra-high SFR of gel was interpreted by the Flory-Huggins lattice theory. High PACl level resulted in the coordination of aluminum ions with the non-terminal carboxyl groups and reduced the surface charge, and thus, caused gel collapse and floc formation, corresponding to rather low SFR values. Preferential coordination combined with the Flory-Huggins lattice theory revealed in this study offered a molecular level fouling mechanism in the coagulation- microfiltration (MF) process for water treatment.

Minimization of halogenated DBP precursors by enhanced PACl coagulation: The impact of organic molecule fraction changes on DBP precursors destabilization with Al hydrates

The destabilization of halogenated disinfection-by-product (DBP) precursors by coagulation are mostly subjected to Al speciation of polyaluminum chloride (PACl) and the fraction of dissolved organic matter (DOM), which significantly affect the minimization of halogenated DBP precursors, such as trihalomethane (THM) and haloacetic acids (HAA), in post-chlorination. In this study, the destabilization of DOM in the solution of humic acid (HA) with and without algogenic organic matter (AOM) using two PACl coagulants with different Al speciation was investigated, along with the identification of optical properties for DOM fractions. Additionally, total THM and HAA formation potential of the supernatant before and after coagulation-sedimentation were determined. The results showed that high polymeric Al-containing PACl (PACl-H, 66% Al13) outcompetes in destabilizing HA than commercial PACl (PACl-C, 29% Al13, 32% Al(OH)3). However, the removal of DOM in HA/AOM mixture by both PACl coagulants are significantly suppressed with greater removal of humic-like and fulvic-like substances than aromatic protein-like substances after coagulation-sedimentation, where PACl-C shows superiority in the removal of hydrophobic and hydrophilic substances with MW around 1 kDa than PACl-H. In the absence of AOM, total THM and HAA formation potential were effectively reduced for HA coagulation by both PACl, but vice versa with the presence of AOM, especially for cellular organic matter (COM). Minimization of halogenated DPB precursors by coagulation are predominated by destabilized hydrophilic molecule fractions with Al hydrates. It is concluded that PACl-H favors charge neutralization to destabilize total carbonaceous DBP (C-DBP) precursors in HA or HA/AOM mixture and the corresponding C-DBP formation potential is lower compared to PACl-C that predominates adsorption and co-precipitation in destabilizing C-DBP precursors.

Pengaruh Penambahan Dosis Koagulan Terhadap Parameter Kualitas Air dengan Metode Jartest

Water is one of the important components of human life or other living things. With the increasing number of residents, the need for clean water has also increased. However, this increase in demand is not offset by the availability of clean water due to the lower quality of water produced by the water treatment plant. Therefore, it is necessary to do alternative water treatment so that clean water needs can be sufficient. One method of processing clean water that can be done is the Jar test method. This study aims to determine the effect of coagulant dose addition on water quality parameters including pH, turbidity, TDS and total hardness of the Manisrejo City Madiun well water sample after water treatment. The research method is carried out through three stages, namely the preparation stage, the instrument analysis stage and the experimental stage. Where the type of coagulant used is Poly Aluminum Chloride (PAC). From the research that has been done, the optimum PAC coagulant dose is 43 mg / l. The conclusion obtained in this study is that the greater the coagulant dose added to the water sample, the smaller the pH value, the value of turbidity, the TDS value and the total hardness of the water sample.

Characterization and influence of floc under different coagulation systems on ultrafiltration membrane fouling

A hybrid system was developed in this study consisting of different coagulation systems and ultrafiltration (UF). Property and effect of flocs formed in different coagulation systems on ultrafiltration membrane fouling control were investigated. All three coagulation systems, as pretreatment of UF, were effective in improving membrane flux and reducing membrane resistance within an appropriate range of natural organic matters (NOM) concentration. At high initial NOM concentration, the performance of polyaluminum chloride (PAC) on NOM removal and fouling control was severely limited. For PAC-poly dimethyl diallyl ammonium chloride (PAC-PolyDMDAAC) coagulation system, the limitation of initial NOM concentration on removing NOM and alleviating membrane fouling was slightly weakened, indicating composite flocculant PAC-PolyDMDAAC produced larger flocs through combined action of charge neutralization and adsorption bridging. In PAC + PolyDMDAAC dual coagulation system, the combined action of adsorption-bridging effect, sweeping effect, and charge neutralization were the mechanisms under both low and high initial NOM concentration. Although the flocs formed in PAC + PolyDMDAAC dual coagulation system had poor recovery ability compared with those formed in PAC and PAC-PolyDMDAAC coagulation system, flocs formed through adsorption-bridging and sweeping had large size and higher ability to resist shear force, resulting in the formation of cake layer with porous and fluffy structure and less blockage in membrane pore in PAC + PolyDMDAAC dual coagulation system. These results demonstrated that dual coagulation system combined PAC coagulation and PolyDMDAAC flocculation as a pretreatment of UF process can improve the characteristics of flocs and structure of cake layer for improving NOM removal and controlling membrane fouling.

Application of hybrid coagulation–ultrafiltration for decentralized drinking water treatment: impact on flux, water quality and costs

Abstract Decentralized membrane-based water treatment represents an attractive and viable approach to safe water supply in low-income areas, but its widespread adoption requires cost-effective antifouling strategies. Although the antifouling mechanisms of Al-based coagulants have been widely investigated, there is little data about their impact on costs and treatment efficiency for decentralized membrane-based systems. In this study, a comparative assessment of two decentralized ultrafiltration (UF) units with and without polyaluminum chloride (PACl) coagulation was undertaken to evaluate the influence of coagulation on the fouling, water quality, and costs nexus. The results showed that PACl suppressed both total fouling and hydraulically irreversible fouling. A matched-pair analysis also revealed that PACl improved the permeate quality by enhancing the removal of particulates and dissolved organics. Compared with the conventional UF system, the hybrid coagulation–UF system contributed to a 21% increase in the flux rate, allowing for a 27% reduction in membrane area and thus, providing cost benefits in terms of both capital and operating costs. These results suggest that PACl coagulation is potentially a cost-effective antifouling method for decentralized membrane-based water systems.