High Turbidity Removal Efficiency Research Articles

Optimization of Dissolved Air Flotation (DAF) process for the treatment of oily water from biodiesel production

Biodiesel production has become one of the most efficient ways of diversifying the energy matrix. However, the increase in biodiesel production increases the generation of wastewater. Therefore, this study aimed to characterize the wastewater generated in the biodiesel washing process, obtained by the alkaline transesterification of sunflower oil, and to evaluate its treatment by the dissolved air flotation (DAF) system, using a Central Composite Rotational Design (CCRD). The first DCCR was carried out with 4 independent variables: pH, Coagulant Dose (CD), Polymer Dose (PD), and Recirculation Rate (RR), with the response variables being apparent color removal and turbidity removal. Based on the results of the first DCCR, optimization tests were designed with DC and DP as independent variables and apparent color, turbidity, COD, and oil and grease (OG) as response variables. The process showed high apparent color and turbidity removal efficiency. The best results were obtained in tests 10 (DC = 1545 mg.L-1 and DP = 1050 mg.L-1) and 3 (DC = 700 mg.L-1 and DP = 8.8 mg.L-1), with the removal of 99.88% and 99.22%, respectively. For the COD and OG parameters, the best results were observed in tests 8 (DC= 555 mg.L-1 and DP= 6 mg.L-1) and 5 (DC= 1050 mg.L-1 and DP= 6 mg.L-1), with 98% and 99.42% removal, respectively. FAD treatment using the combination of coagulant and cationic polymer proved to be highly efficient in treating wastewater from biodiesel production.

The Effect of Cone Area Variations on the Continuous Discharges Flow (CDF) Method Sedimentation Unit as a New Method for Raw Water Turbidity Removal

The Sedimentation Unit Continuous Discharges Flow (CDF) method is a modification by adding a continuous and controlled discharge flow as a net force acting on the particles to increase the efficiency of turbidity removal by applying the principle of a leaky tank at the bottom of the settling zone. The production capacity of the sedimentation unit using the CDF method is reduced due to the CDF flow of 6% of the flow rate so it needs to be recirculated. This study aims to maintain the production flow rate of the system and increase the efficiency of turbidity removal by recirculating the CDF flow. The research reactor consisted of a coagulation unit, flocculation unit, and sedimentation method using 6% CDF with a flow rate of 240 L/hour and 360 L/hour, and variations in the recirculation flow of 6% CDF to the flocculation unit were 0%, 25%, 50%, 75%, and 100 %. The sedimentation detention time at a flow rate of 240 L/hour and 360 L/hour was 90 minutes and 60 minutes, respectively. Research on a laboratory scale with raw water turbidity of 25,536 NTU. The results showed that the greater the CDF flow recirculation value, the higher the turbidity removal efficiency. Rank Spearman analysis, the correlation value of the CDF flow recirculation value to the efficiency of removal of turbidity is 0.980 and the significance value is 0.00 which means strong and significant. The highest turbidity removal efficiency was achieved at the 100% CDF flow recirculation value, ie at 240 L/hour flow rate was 87.21% with final turbidity 3.267 NTU, while at 360 L/hour flow rate was 82.50% with final turbidity 4,528 NTU. Uprating the flow rate in the experiment was able to produce a final turbidity value that met the drinking water quality standard, which was 5 NTU

Recycled membrane for drinking water treatment with high iron and manganese concentrations

Membrane recycling by oxidative treatment is one alternative to minimize the impacts of the disposal of end-of-life (EoL) reverse osmosis (RO) membranes. In parallel, iron (Fe) and manganese (Mn) contamination in surface and groundwater is increasing. This study aims to develop recycled membranes that retain dissolved Fe and Mn from water for supply purposes. EoL RO membranes were recycled with sodium hypochlorite (NaClO, 10–12%) solution at exposure dose between 4000−80,000 ppm∙h to produce a recycled membrane with high flowrate and high Fe and Mn rejection. EoL RO treated by 40,000 ppm·h showed water permeability of 54.30 L∙h−1∙m−2∙bar−1 and Fe and Mn rejection of 99% and 65%, respectively. Potability for Mn (> 98%) was enhanced by integrating pre-oxidation stage with NaClO (5 mg∙L−1 of Cl- and pH 8) to the recycled membrane process. Recycled module performance was evaluated for water treatment from Paraopeba River on pilot scale, in continuous operation (51 h) and pressure of 1 bar. At pilot scale, recycled membrane obtained a water permeability of 40.33 L∙h−1∙m−2∙bar−1, like a moderately open ultrafiltration membrane. Fe and Mn removals were > 99% and > 90%, respectively, with high color and turbidity removal efficiency. Membrane recycling cost was predicted to be US$ 4.08/m², and the capital (CapEX) and operating (OpEX) expenditures for the single-household system was US$ 671.18 and US$ 22.52 to m3·day−1 of treated water. Therefore, the recycled membrane was shown to be efficient in removing dissolved Fe and Mn, and it is promising for decentralized water treatment.

The Potential of Moringa oleifera Seed in Water Coagulation-Flocculation Technique to Reduce Water Turbidity

Using a safe and easy-to-apply economic flocculant to replace alum is necessary to expand and enhance the water quality in rural regions where traditional water treatment is unavailable. The seed of Moringa oleifera is locally available in large volumes and is feasibly economical. A compatibility and applicability research of the easily accessible local Moringa oleifera seed extract (MOSE) was conducted to examine its potential utilization to lessen various degrees of water turbidity at 30 ± 2 °C. The study concerns the optimum dosage of MOSE to give high turbidity removal efficiency in the water. Experiments were carried out for nine turbidity samples: 5, 10, 15, 30, 50, 70, 100, 200, and 300 NTU. The turbidity removal efficiency of up to 89% was achieved for high initial turbid water 300 NTU. However, for low turbid water, its potential efficiency declined. The results demonstrate that the de-oiled extract is substantially more efficient than the crude extract in agglomerating colloidal particles of low initial turbidity samples and achieved up to 76% removal rate. The results of the ANOVA confirmed that the regression model was significant at (p < 0.05) for residual turbidity after the treatment process. The study also demonstrates that a pseudo-first-order kinetic model matched well the nature of the removal of colloidal particles with MOSE in water to form flocs. The study also indicates that the characteristics of water treated with crude MOSE produce little change in electrical conductivity and salinity. However, the hardness and alkalinity of water decreased significantly depending on the initial hardness and the amount of MOSE applied (p < 0.05).

Evaluation of the Feasibility of Foam Glass as Filter Media in Rain Garden

Objectives:In order to recycle and resource waste glass, the feasibility of foam glass as filter media was evaluated, and column experiments using foam glass media were conducted to confirm the applicability as filter media in rain garden. Through this experiment, various design factors to be considered can be derived in application of foam glass media in the rain garden.Methods:Sieve analysis and SEM/EDS analysis were conducted to confirm the physicochemical properties of the foam glass. Column experiments filled with only foam glass and mixtures of sand and foam glass were conducted to simulate rain garden to evaluate the removal efficiency of suspended solids and turbidity using the foam glass media, head difference (&lt;i&gt;Δh&lt;/i&gt;) and hydraulic conductivity (&lt;i&gt;K&lt;/i&gt;) changes, and calculation of filtered suspended solids loading using both discrete and cumulative mass approach. Finally, comparison of filtration performance with various filter media used in LID facilities was performed to evaluate the feasibility of foam glass media in rain garden.Results and Discussion:Since foam glass media has a lower density than water, homogeneous particle size, and smooth surface with pores of various sizes, foam glass media effectively induces internal capture and external adsorption of suspended solids. Foam glass media has been applied to high suspended solids and turbidity removal efficiency. As the suspended solids inflow load increased, clogging occurred in the pores and the removal efficiency gradually decreased, but the foam glass media with lower density than water was continuously disturbed and rearranged due to the head difference energy, and some clogging were alleviated by rearrangement of pores and channels. The load of suspended solids in precipitated, adsorbed, and retained on the foam glass was calculated using the effluent sample (discrete) collected at regular time intervals and the continuously accumulated sample (cumulative) from the output. The filtered suspended solids load calculated using the cumulative mass approach was higher due to the estimation of the amounts of suspended solids remaining in the filtration column is lower because the samples (discrete) collected at regular time intervals from the output do not reflect the amount of suspended solids that change over time. Thus, the amounts of suspended solids removed through the filtration process can be much more accurately estimated using the cumulative samples. Finally, when comparing the removal efficiency with other filter media, foam glass can be used as excellent filter media with higher removal efficiency and greater lifespan.Conclusion:Foam glass media with smooth surface, pores of various sizes, and lower density than water can rearrange and regenerate pores to alleviate some clogging, resulting in high suspended solids and turbidity removal efficiency for a long period of time. Considering that the amount of suspended solids filtered is determined by various factors such as particle size and distribution, porosity, depth, linear velocity, and inflow load of the suspended solids, the feasibility test using foam glass media through long-term field experiments is warranted. The amounts of suspended solids removed through the filtration process can be much more accurately estimated using the cumulative samples.

The structure and flocculation characteristics of a novel exopolysaccharide from a Paenibacillus isolate

Bioflocculants like polysaccharides are excellent alternatives to harmful synthetic flocculants and usability under stricter levels of ecosystem protection. In this study, an exopolysaccharide producing strain Paenibacillus sp. M21629 was isolated. The exopolysaccharide was abundant in carboxylic groups and named floccuronic acid with a high weight average molecular weight of 2.38 × 108 Da. The hexasaccharide repeating units of floccuronic acid were →3)-α-D-Manp-(1 → 3)-4-Suc-β-D-Manp-(1 → 3)-β-D-Glcp-(1 → 4)-β-D-GlcpA-(1 → 4)[4,6-Pyr-β-D-Galp-(1 → 3)]-β-D-Galp-(1→. The floccuronic acid at 0.5–1 ppm showed high turbidity removal efficiency in kaolin suspension (99.8%), coal wastewater (98.8%), and high-turbidity drinking water (89.2%). The flocculation ability of floccuronic acid depended on the instability of solid particles. Owing to these encouraging results, floccuronic acid is expected to be a useful bioflocculant applied in wastewater treatment and the utilization of water resources.

Potential application of natural coagulant extraction from walnut seeds for water turbidity removal

Abstract In this study, natural coagulant obtained from walnut seeds was used in water treatment for the removal of turbidity as a coagulant and as a coagulant aid with alum. The study was conducted by using a jar test under various operational parameters. The tests were carried out with initial turbidity of 10–200 NTU, pH of 3–11, and natural coagulant dose of 1–5 ml/L. The characterization of walnut natural coagulant was carried out using SEM, FTIR, EDX, and zeta potential analyzer. The coagulation activity and turbidity removal efficiency were evaluated for each run. The optimum dose of the walnut seed extract may be found to be 3 ml/L. The highest turbidity removal efficiency was achieved at pH above 7. Walnut seed extract used as coagulant and with alum was able to enhance coagulation process performance and decrease the alum dose required for the coagulation process performance and decrease the alum dose required for the coagulation process. Walnut seed extract has a negligible impact on organic matter content in the coagulated water. Furthermore, ANNs model of turbidity removal using walnut seed extract was conducted and yielded a high coefficient of determination (R2 of 0.96).

Removal of organic pollutants from produced water by batch adsorption treatment

This paper studied the adsorption of chemical oxygen demand (COD), oil and turbidity of the produced water (PW) which accompanies the production and reconnaissance of oil after treating utilizing powdered activated carbon (PAC), clinoptilolite natural zeolite (CNZ) and synthetic zeolite type X (XSZ). Moreover, the paper deals with the comparison of pollutant removal over different adsorbents. Adsorption was executed in a batch adsorption system. The effects of adsorbent dosage, time, pH, oil concentration and temperature were studied in order to find the best operating conditions. The adsorption isotherm models of Langmuir, Freundlich and Temkin were investigated. Using pseudo-first-order and pseudo-second-order kinetic models, the kinetics of oil sorption and the shift in COD content on PAC and CNZ were investigated. At a PAC adsorbent dose of 0.25 g/100 mL, maximum oil removal efficiencies (99.57, 95.87 and 99.84 percent), COD and total petroleum hydrocarbon (TPH) were identified. Moreover, when zeolite X was used at a concentration of 0.25 g/100 mL, the highest turbidity removal efficiency (99.97%) was achieved. It is not dissimilar to what you would get with PAC (99.65 percent). In comparison with zeolites, the findings showed that adsorption over PAC is the most powerful method for removing organic contaminants from PW. In addition, recycling of the consumed adsorbents was carried out in this study to see whether the adsorbents could be reused. Chemical and thermal treatment will effectively regenerate and reuse powdered activated carbon and zeolites that have been eaten.Graphic abstract

Effect of processing parameters on mullite bonded SiC membrane for turbid water filtration

A water-filtration membrane made of SiC possesses some excellent properties, but its application is limited by high fabrication cost. In this study, two sets of mullite bonded porous SiC ceramics membranes were prepared at reduced temperature by oxidation bonding method using different processing conditions. Dead-end filtration mode was utilized for the determination of permeability and their efficiency towards removal of turbidity. It was found that all the membranes prepared using different composition, pore formers (graphite, PVC and PMMA) and sintering temperature exhibited high turbidity removal efficiency (> 99%). This study provides an efficient method to prepare porous SiC ceramics with excellent permeability and turbidity removal efficiency, which will be helpful for the design of low cost SiC ceramic filters for water treatment.

Binary coagulation system (graphene oxide/chitosan) for polluted surface water treatment

In this study, chitosan (CS) is used as a natural coagulant aid alongside graphene oxide (GO) to remove turbidity and numerous pollutants from raw and artificially contaminated surface water. The coagulation capability of the system (GO/CS) was assessed with respect to a water sample's turbidity, pH, coagulant dose, settling velocity, and temperature. The presence of CS enhanced the coagulation capacity of GO at varied pH levels and no GO residue was detected in the water after the treatment. The proposed system achieved high turbidity removal efficiency (≥98.3%) for all turbidity levels. A mixture of GO (8 mg/L) and CS (2 mg/L) was ideal to remove algae (99.5%) and bacteria (≥95.0%). Furthermore, it demonstrated a high coagulation capacity to remove dyes, direct brown-2 (DB-2), methylene blue (MB), and Pb(II) ions from artificially contaminated surface water. Interestingly, the sludge exhibited an extraordinary adsorption capacity for DB-2, MB, and Pb(II) ions. The adsorption process followed the pseudo-second-order kinetic model, and was consistent with the Langmuir model, with an adsorption capacity of up to 667.8, 400.7, and 459.1 mg/g for DB-2, MB, and Pb(II) ions, respectively. Therefore, the presented binary coagulation system is of great potential economic value for the treatment of raw surface water and wastewater.

Oil-in-water emulsion separation by PVC membranes embedded with GO-ZnO nanoparticles

Membrane technology is regarded as the most promising approach for oily wastewater treatment. In this study, GO and GO-ZnO nanoparticles were incorporated into PVC membranes to enhance antifouling properties in oily wastewater treatment. The results of FTIR analysis revealed that ZnO nanoparticles were successfully anchored on GO nanosheets. In addition, XRD results indicated that the presence of ZnO increased the distance between GO nanosheets. Fabricated membranes were characterized via contact angle, tensile testing, pure water flux, field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM). FESEM results illustrated that modification of GO with ZnO reduced its agglomeration in the membrane matrix. The reduction of contact angle from 80° for pure PVC membrane to 67° for 0.1% GO-ZnO containing membrane showed that the hydrophilicity of the membranes was enhanced by increasing nanoparticles content. The same trend was observed for water flux of PVC/GO and PVC/GO-ZnO nanocomposite membranes indicating that membranes with 0.05 wt% of both GO and GO-ZnO exhibited the highest pure water flux. The presence of nano additives also increased the mechanical strength of the membranes due to the synergistic property of the nano additives. Finally, the membranes were evaluated in a lab scale cross flow system with synthetic oily wastewater as feed. The results showed that PVC/GO-ZnO membranes had lower flux reduction and higher turbidity removal efficiency than neat PVC and PVC/GO membranes.

Comparative study of turbidity removal efficiency of green pea (Cicer arietinum) seed and pod extract for turbid water treatment

Natural coagulants are considered affordable and efficient substitutes to chemical coagulants for use in water treatment. The study investigated the turbidity removal efficiency of pea seed and pod extracts from surface water. Chemical and proximate analyses of pea seed and pod were evaluated. Optimum values of coagulant dose, pH and stock solution concentrations were determined using jar test. Turbidity removal efficiencies and residual turbidity of the coagulant were also evaluated. The highest turbidity removal efficiency was found to be 98% and 97% at 10% w/v stock solution concentration of the pea seed and pod extract respectively. The optimum pH suitable for coagulation of surface was found to be 6.8 and 6.6 at 10% w/v stock solution of pea seed and pod extract respectively. The pea seed and pod extract were found to be most efficient in removing turbidity from surface water at 10% (w/v) stock solution with optimum dose of 1600mg/L. The p-value was found to be 0.99, 0.0156 and 0.33 for Turbidity removal efficiency, pH and Residual turbidity of pea seed and pod respectively. Pea seed and pod turbidity removal efficiencies are statistically insignificant, but their pH and Residual turbidity values are statistically significant. The findings in this study suggest that both the Pea pod and Pea seed extract are effective in water coagulation, but pea seed extract is more effective in drinking water coagulation, while pea pod extract was cheaper and readily available.

Evaluating the effects of the flow direction on the performance of the rapid sand filter

The rapid sand downflow filter is widely used in water treatment plants. On the other hand, this filter has some drawbacks included the significant development of the head loss via the filter media because most of the rejected particles are removed by the upper layers. As well, the filter particles are redistributed during the backwash process causing the settling of fine particles on the upper part of the filter media, and this needs to increase the number of backwash processes. For these reasons, the cost of the produced water increases. The aim of the present study is to explore the possibility of using the upflow sand filter (UF-Filter) as a good alternative to the downflow sand filter (DF-Filter). To achieve the aims of the present study, a comparison was made between the performance of both filters through simultaneous experiments under different operating conditions. These conditions included changing of the filtering velocity from 5 m/h to 10 m/h and the initial water turbidity with a range of (10 – 200) NTU. The sand media with sizes of (0.6 - 1mm) and with 63 cm of depth was used. Experimental results show that the turbidity removal efficiency of the DF-Filter is of about 1.1 times that of the UF-Filter. On the other hand, the UF-Filter has higher turbidity removal efficiency than the DF-Filter by about 1.1 times when the initial turbidity of the influent water is greater than 150 NTU and the filtration velocity is equal to 10 m/hr. These differences in the removal efficiency between both filters can be considered as few values. The average filtration efficiency of the UF-Filter operated with the filtration velocity of 5 and 7.5 m/h is higher than that of the DF-Filter operated with the filtration velocity of 7.5 and 10 m/h, respectively under the same operating conditions. The filtration efficiency of both filters increases when the backwash was carried out before each experimental process instead of replacing the filter media. Also, the head loss of the DF-Filter is significantly increased due to redistribution of the sand media taking place during the backwash cycle, while the head loss of the UF-Filter is not affected. The head loss of the UF-filter at the end of each experimental run is less than that of the DF-Filter by about (18.18 % - 45.31 %) when the filter medium is replaced and this range is increased to about (53.31 % - 62.34 %) when the backwash is performed prior to the start of the experimental work. Thus, the decrease in head loss leads to an increase in the filter running time and decrease the number of backwash process.

Investigating the efficiency of coagulation and flocculation process in wastewater treatment of paper and cardboard recycling industry

ABSTRACT In addition to the large volume, the generated wastewater in paper and cardboard recycling industry contains various organic compounds and dyes. Treatment of these wastewaters is difficult due to the diversity of contaminants and the complexity of their chemical structure. This study aimed to investigate the efficiency of the coagulation and flocculation process by the new mixture of coagulants for wastewater treatment in one of the paper and cardboard recycling industries. To determine the efficiency of the coagulation and flocculation process in removing the parameters, including turbidity, colour, TSS, and COD, the Jar Test was used in laboratory conditions. By changing the variables, such as pH, coagulant type (PAC/MgCl2, PAC/Polymer, MgCl2/Polymer, MgCl2/PAC, PAC/MgCl2/Polymer), coagulant dose, and polymer dose, the optimal conditions were determined. Based on the results, the highest turbidity removal efficiency was achieved for the combination of coagulant and coagulant aid (PAC/MgCl2/Polymer) at pH 11. According to the experiments, the highest removal efficiency of turbidity, colour, COD and TSS were95.43%, 25.16%, 16.16%, and 83.33%, respectively. According to the obtained results, the coagulation and flocculation is a suitable method to remove turbidity and suspended solids in the paper and cardboard recycling industry wastewater. However, in order to remove more colour and COD, additional treatment is required.

Ammonium removal of biological roughing filter for rural drinking water pretreatment

Abstract Ammonium pollution of source water has become a challenge in rural water supply. Biological roughing filtration combining with low energy consumption and simple operation would be a potential solution to this issue. This study was conducted to investigate ammonium removal by biological up-flow roughing filter packed with ceramic media. Low flow rate did affect the ammonium removal and higher flow rate was suggested, while intense backwashing only showed a slight impact. At 4 m/h, an average reduction of about 51% was obtained, and NH4+-N effluent concentration could be below 0.5 mg/L within a NH4+-N loading rate of 0.1 kg/(m3·d). Biomass and biological activity assessment were performed as well as microbial community analysis. High abundance of nitrifying bacteria contributed to ammonium removal with Nitrospira and Nitrosomonas accounting for 6.59% and 1.12% of the bacteria community, respectively. In addition, the roughing filter showed high turbidity removal efficiency of about 70%. This study suggested that a biological roughing filter could be employed to help rural drinking water plants adapt to the seasonal change and moderate deterioration of source water quality in terms of ammonium pollution with low-cost and simple operation.

Natural agents as auxiliaries in water clarification: literature review and experimental evaluation

The increasing demand for water resources (primarily for human consumption and industrial and agricultural activity) is driven by socio-economic development, and population growth. Recent research has been focusing on alternative coagulants based on natural elements, as opposed to the commonly used iron and aluminum salts, for use in water and wastewater treatment processes. In this context, a thorough literature review on alternative coagulants and their application to water treatment processes has been conducted in this work. In addition, three experiments have been conducted with a widely used natural organic coagulant (Moringa oleifera). The alternative clarification system used is the helically coiled tube flocculator (HCTF), with high turbidity removal efficiency and low processing times. A comparative analysis of the turbidity reduction over time was performed with samples collected after 600, 900, 1200, 1500, 1800, 2100, 2400, and 2700 s from the hydraulic circuit. The process efficiency using the proposed alternative coagulant reached 95.3% (after 1800 s). The turbidity removal efficiency remained almost constant after 1800 s, with variations below 1%. These results prove that natural alternative agents can be powerful tools in the water treatment process, with efficiency values exceeding those obtained using chemicals (e.g., aluminum sulphate) as coagulant/ flocculant agents.

Microwave-assisted extraction of banana peel bio-flocculant and its potential in wastewater treatment

Coagulation-flocculation process has been continuously investigated as a significant process to reduce water turbidity in wastewater treatment, owing to the process simplicity and economic feasibility. In this research, the performance of extracted banana peel as bio-flocculant for turbidity removal under different extraction methods and conditions was investigated. Microwave-assisted extraction (MAE) was found to be more effective compared to conventional heating extraction (CHE), with higher turbidity removal efficiency at 45.16%, shorter extraction time and lesser energy requirement. The most optimum turbidity removal percentage was attained by using bio-flocculant extracted with low microwave power, 30 s of extraction duration and banana peel dosage of 5 g/100 ml distilled water. The banana peel bio-flocculant demonstrated potential to be used as a replacement to alum as the turbidity removal as high as 97.06% was recorded using bio-flocculant alone, which was not significantly different from 99.22% removal through the utilization of alum. This offered a greener option in coagulation and flocculation process in reducing utilization of chemical-based coagulant.

Growth of Desmodesmus subspicatus green microalgae and nutrient removal from sugarcane vinasse clarified by electrocoagulation using aluminum or iron electrodes

Sugarcane ethanol production generates considerable quantities of vinasse, its main wastewater. Microalgae cultivation is a promising option for effluent remediation, since the generated biomass can be feedstock for biofuel and bio-based chemical production. Due to vinasse high turbidity, pretreatment is necessary to clarify this effluent, adapting it as a mixotrophic culture medium. In this context, the present research evaluated the integrated process of electrocoagulation (EC) of sugarcane vinasse with aluminum or iron electrodes and subsequent cultivation of green microalgae Desmodesmus subspicatus. Results indicate pH neutralization and high turbidity removal efficiency by EC with both electrode materials. Aluminum EC and subsequent microalgae cultivation removed 66 and 75% of initial total organic carbon and total nitrogen, respectively, with biomass productivity of 1.45 g L-1day-1 and maximum specific growth rate of 0.095 h-1. Microalgae productivity was inferior in vinasse pretreated by iron EC, suggesting possible interference of ferric compounds in the microalgal development.

Use of Acorn Leaves as a Natural Coagulant in a Drinking Water Treatment Plant

In this study, the use of acorn leaves as a natural coagulant to reduce raw water turbidity and globally improve drinking water quality was investigated. The raw water was collected from a drinking water treatment plant located in Mila (Algeria) with an initial turbidity of 13.0 ± 0.1 NTU. To obtain acorn leaf powder as a coagulant, the acorn leaves were previously cleaned, washed with tap water, dried, ground and then finely sieved. To improve the coagulant activity and, consequently, the turbidity removal efficiency, the fine powder was also preliminarily treated with different solvents, as follows, in order to extract the coagulant agent: (i) distilled water; (ii) solutions of NaCl (0.25; 0.5 and 1 M); (iii) solutions of NaOH (0.025; 0.05 and 0.1 M); and (iv) solutions of HCl (0.025; 0.05 and 0.1 M). Standard Jar Test assays were conducted to evaluate the performance of the coagulant in the different considered operational conditions. Results of the study indicated that at low turbidity (e.g., 13.0 ± 0.1 NTU), the raw acorn leaf powder and those treated with distilled water (DW) were able to decrease the turbidity to 3.69 ± 0.06 and 1.97 ± 0.03 NTU, respectively. The use of sodium chloride solution (AC-NaCl) at 0.5 M resulted in a high turbidity removal efficiency (91.07%) compared to solutions with different concentrations (0.25 and 1 M). Concerning solutions of sodium hydroxide (AC-NaOH) and hydrogen chloride (AC-HCl), the lowest final turbidities of 1.83 ± 0.13 and 0.92 ± 0.02 NTU were obtained when the concentrations of the solutions were set at 0.05 and 0.1 M, respectively. Finally, in this study, other water quality parameters, such as total alkalinity hardness, pH, electrical conductivity and organic matters content, were measured to assess the coagulant performance on drinking water treatment.

Scale-inhibition and flocculation dual-functionality of poly(acrylic acid) grafted starch

Natural-polymer based water treatment agents have recently received much more attention due to their environmental friendliness, widespread availability, and prominent structural features. Starch-graft-poly(acrylic acid) (St-g-PAA) is a simple natural-polymer based material that can be obtained easily by a one-step graft copolymerization. When used as a water treatment agent, St-g-PAA exhibits both effective scale-inhibition performance and high turbidity removal efficiency. The scale-inhibition efficiency of St-g-PAA against calcium carbonate (CaCO3) is approximately 94% at the optimal dose in a static test of approximately 40 mg/L. Dispersion, crystal lattice distortion, and chelating effects all play important roles in the scale inhibition. When St-g-PAA is used as a coagulant aid for polyaluminum chloride (PAC) in the flocculation of a real hairwork wastewater, the highest reduction of the optimal PAC dose is more than 30% while the turbidity reduction is about 97% at the same time, both floc size and compactness increase, and the final settling efficiency also improves evidently. The efficient bridging flocculation effects account for the effective turbidity removal. The prominent scale-inhibition and flocculation dual-functionality of St-g-PAA is intrinsically ascribed to its distinct anionic linear branched-chain structure.