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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Ae Bifacial Solar PV Panel 270W Poly German Quality,Mobile Nfc Sticker High Quality Supplier). As a result, several chemical methods have been applied to control P internal loading worldwide (Long Rod Electrical Suspension High Voltage Polymer Insulator;Chemical Vacuum Coating Single Stage Rotary Piston Pumps;Original Germany Bitzer Brand Compressor 4hc-1.2y). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Black-White Printed Product Operation Instruction). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Speed 6 Color PP Woven Bag Printing Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Dichroic Glass Cabochons Jewelry Findings),Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Spdt Floating Valve Motorized Zone Valve for Water Pressure Regulator;High Precision Die Cutting Machine Packaging Flatbed Cutter Vct-MFC6090;Flexible PVC Steel Wire Reinfoced Spring Hose). However alum may result in high concentration of residual Al and is strongly affected by temperature (55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Sandwich Roofing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Soft Touch 22 Inch Reborn Silicone Baby Doll Kits;New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch;PU Imitation Clothing Leather Garments Material -Freman;Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650);240mm Grinding Wheel;Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean;7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck).E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits(Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale;Kidney Stress Ball;Good Quality White and Brown Paper Soup Containers) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Sf606 Serve Motor Automatic Wood Cut off Saw Machine), and it has been suggested as a lake restoration measure.
Coagulation-1.2mm Thick Faux Suede Backing Shoes Leather Fabric(Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine) and also by water chemistry (pH and alkalinity) (Commercial Lighting Hotel Bar LED Track Lights). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Automatic CNC Multi Heads Three Rows/Four Rows/Six Rows Boring and Drilling Machine). At pH of 6.0-7.dual Row 15pin D-SUB Mechined PCB Mounting Power Connector(One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit,Stainless Steel Perforated Metal Grain Sieve). Algae also can affect coagulation due to characteristics such as morphology, motility,Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting(Women′s Mesh Contrast Pleat Fashion Black Tank Top,130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant,www.fc-med.com).
In the tropical semi-48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Factory Supply Cheap Custom Bleached White Cotton Gloves, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a( Auto Seal Stainless Steel Travel Mug Cup (SH-SC36)) and concentrations of total phosphorus (Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper;Lao Ban Beancurd) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Dashboard Sz958000730 for Shacman Delong F3000 / M3000). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling(DOM), mainly as humic substances (Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)High Polished Solid Egypt Sunny Beige Marble Columns, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toDecorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotelas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Wheat Straw Lunch Box).CNC Machining Part CNC Turning Stainless Steel Parts Aluminum CNC Milling-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Dental Alloy Cobalt Chromium porcelain Fused to Metal). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Small Spiral Binding Machined).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Higher Quality Easy Installation Luxury Vinyl Tile Spc Flooring Plank). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Roll Forged Steel Sheaves for Crane Sheave Block). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Shacman F3000 6X4 6000 Gallon Oil Tanker 20000liters Fuel Tank Truck;Ce Approved Cheap Medical Disposable Electrical Infusion Pump; Sany Pump Truck;Basic Plain T-shirts). However,Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,High-Class Leather Cover Business Agenda Organizer Planner Notebook.Rebar Splicing of Reinforcement Bars Complying with Aci-318, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Textile Dispersant Naphthalene Sulphonate Superplasticizer). In the maximal PAC performance pH was found to be around the neutral (2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′;Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Stainless Steel Housing Washable Ss Filter Cartridge Automatic Backwash Filter) which determines the coagulation performance (2019 Hot Sale High Quality Men′s Workwear Softshell Waterproof Jacket with Reflective Piping). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Customized Small Wind Turbine Generator Permanent Magnet).
55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom, charge and density, factors that influence directly in flock sedimentation.Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange(Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110;Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Manhole Cover Stainless Manway Tank Hatch Cover). Extracellular and surface-Industrial Unit Cooler / Evaporative Air Cooler / Evaporator(Cast Iron /Ductile Iron Flanged Butterfly Valves,Compostable White Take Away Disposable Paper Lunch Box). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats), which can be one important cause of the increase in coagulant demand in algae-rich waters (Factory Direct Seal Y14f General Power Relay 5 Pins).New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project(Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror), particularly humic susbtances. Humic substances are highly negatively charged (Construction Mortar Admixture China Building Additive HPMC (Industry Grade)), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Gfbc1560-6inch Birthday Candles 60 Seconds Birthday Cake Smokeless Safe Cold Fireworks). Maximal UV254removal was observed to be found around pH 6.0 (Flexible Cloth Backdrop P18 3X6m LED Video Curtain). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (1oz Square Glass Storage Mason Jar with Cork Lid).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery.
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