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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 (Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel,Round AISI Tube Prices 304 Stainless Steel Pipe). As a result, several chemical methods have been applied to control P internal loading worldwide (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace;Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven;Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Automatic Mango Juicer Filling Machine / Canned Juice Production Line). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Professional Double Cup Fully Automatic Coffee Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Food Shop Desktop Frozen and Cooked Meat Slice Cutting Machine),Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels. 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 (Low-Cost Tree Stump Crushing Machine with Widely Using;Plant Stands & Accessories Glass Hanging Flower Pot Bracket;Seamless Circular/Square/Rectangular Steel Tube). However alum may result in high concentration of residual Al and is strongly affected by temperature (Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z) 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 (Hdg Carbon Steel Hex Nut). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Lightweight New Design Girl Fashion Bags Children School Backpack;Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier;New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price;Round 10W LED CCT Tuneable Dimmable Down Lights;Wireless Charger PCBA Board China Shenzhen Supplier;Customize Cartoon Printing Logo Brand Silicone Swim Cap; Citycoco).Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools(Type F High-Rise Clip Drive/Worm Hose Clamp;28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket;Police Concealable Bullet Proof Vest (Aramid Ballistic Panel);New Version Breakage-Proof Multihead Weigher for Biscuits) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer), and it has been suggested as a lake restoration measure.
Coagulation-Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric(FDA Approved Custom Eye Mask Packaging Bag / Mylar Foil Facial Mask Pouch / Cosmetic Cream Sachet) and also by water chemistry (pH and alkalinity) (European Type 7 Pin 13 Pin 12V 24V Brass Contact Truck Vehicle Trailer Plug Socket). 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 (Tungsten Carbide Chip Inserts). At pH of 6.0-7.Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17(Zumex Style Speed Tank Podium Commercial Citrus Juicer,CNC Metal Fiber 2000W Laser Cutter with Switching Working Table). Algae also can affect coagulation due to characteristics such as morphology, motility,Low Price Promotional Concrete Cement Mortar Plaster Pump Machine(Unistrut Type Slotted Steel Strut Channel or C Channel,China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder,Dd Series Air Cooler).
In the tropical semi-18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display-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.34*25cm Office File Pocket Felt A4 Document Bag. 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
Hex Washer Heaf Self-Drilling Screw with Steel and Rubber Washer, 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(Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials) and concentrations of total phosphorus (Surgical Drape Angio Pack Angiography Drape Pack;Fabric Production Line) 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 (Prefab Factory Price High-Quality Modern Shipping Container Clinic). 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). UV254Best Quality Square Mini Takoyaki Grill Pan with Helper Handle(DOM), mainly as humic substances (Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion).
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.)Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern, 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 toKids Waterproof Cow Leather Wool Felt Warm Fur Boots for Winteras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Removable Battery Electric Bike M3 Big Power 2000W).High Drying Efficiency Wood Sawdust Dryer for Sale-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 (Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet). 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 UV254Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Reducer Hydraulic Fitting with Swivel Nut (2D)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Machine Boltsd).
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(Colorful Commercial PVC Vinyl Flooring for Office). 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 (Auto Air Poppet Valves Cover Plastic Mould / Mold). 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,Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture, 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 (High Power/Torque Density 7.5kw 2500rpm AC Servo 3 Phase Motor;10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps;Prefab Multifunctional Steel Structureg for Wholesales Construction Material;www.sdjtec.com). However,Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant.
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,Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO).Best Price Aluminium Sulphate for Water Treatment, 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 ( Paper Bags). In the maximal PAC performance pH was found to be around the neutral (A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet;304 Stainless Steel Pipe Manufacture in China). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hospital Equipment 23L Benchtop Autoclave) which determines the coagulation performance (www.yasentag.com). 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 (Light Controller DMX Controller for Stage Light).
Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630, charge and density, factors that influence directly in flock sedimentation.Sinbeda LCD Display for Sony Xperia Z1 Touch Screen(Alluvial Sand Tin Mining Process Equipment Rollers Electrostatic Separator;Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers). 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 (Fasion Style Custom Indian Embroidery Patch). Extracellular and surface-ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar(Iec 60309 Adapter,Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt), which can be one important cause of the increase in coagulant demand in algae-rich waters (Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C).Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes(Plastic Reflective Raised Pavement Marker Road Stud), particularly humic susbtances. Humic substances are highly negatively charged (Fire And Jockey Pump), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style). Maximal UV254removal was observed to be found around pH 6.0 (PU Foam Plastic Squishy Slow Rising Toy for Unicorn). 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 (Top Quality Polar Wohlenberg Paper Cutting Blade).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c.
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