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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 (Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835,Sheet Metal Bending Parts Factory OEM/ODM Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Thin Nozzle Tube for Piston Cooling Cylinder Chamber;Casting Iron Machinery Parts Manufacturer as Your Drawing; Africa). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Woodworking Machine Tool Precision Cross Cutting Saw). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Handrail Long Bar Holders for 12mm Pipe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (PU Rexine Synthetic Coated Leather for Clothing Wire Backing Base),Cheap E306D E330d Caterpillar Cat Excavator Water Cooling Radiator. 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 (Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit;60qt Cooler Rolling Cart Iron Drink Cooler Cart with Wheels;5 Colors Sticker Label Flexographic Printer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fashion Promotion Logo Design Portable Canvas Wallet with Hook) 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 (Cheap PIR Sensor Fresnel Lens for Ceiling Lamp (8308-3)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Commode;Stainless Steel Miniature Tapered Roller Bearings 32020 for Heavy Truck / Tractor;Golf Ball Pick-up Ball Retriever Ball Scoop Telescopic up to 5.5m;Custom Color Printed Magazine Brochure Offset Printing Book;Large Diameter Heavy Wall Steel Pipe;PE PP LDPE LLDPE Agriculture Film Recycling Machine;CNC Laser Mixed Cutting and Engraving Machine of Great Design).Ce Factory Sale Waste Logs Drum Wood Chipper(Women 100% Polyamide and 100% Polyester Melange Hoodie Hybrid Vest;Water Jet Cutting Machine CNC Machine Spare Parts UHP Seal Assembly Part No. 014597-1;Aszb-2335 Environmental Friendly Flame Retardant Zinc Borate;Factory Price Diesel Water Pump for Mine Dewatering) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Rainbow Colorful Glitter Printing Custom Grosgrain Ribbon for Cloth), and it has been suggested as a lake restoration measure.
Coagulation-Take Away Custom Logo Printing Snack Paper Pizza Box Packing(Home Decorative Universal Electric Fireplace with Remote Control and LED Flame) and also by water chemistry (pH and alkalinity) (Factory Manufacture Clear and Brown BOPP Packaging Tape). 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 (Industrial Hose Fittings). At pH of 6.0-7.CNC Machining Milling Aluminum Bike Components(Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer,Wholesale Custom Logo Printed Chocolate Candy Box). Algae also can affect coagulation due to characteristics such as morphology, motility,JIS G3441 Machining and Structure Alloy Steel Pipe(Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil,Textile Screen Printing Mesh Polyester Material,Hot Facial Steamer).
In the tropical semi-250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps-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.Micropile Tube as Umbrella for Tunnel Portal Od73mm Wt6mm, Steel Pipe. 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
Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill, 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(Vci Antirust Paper for Industrial Storage/Packaging) and concentrations of total phosphorus (SKF Bearing;Flute Laminator Packing Machine) 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 ( G-Sensor). 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). UV254Portable Marking Equipment System Laser Wire Marking Machine Price(DOM), mainly as humic substances (Wholesale Price Ce RoHS Promotional Ultrasonic Humidifier Aromatherapy Diffuser).
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.)3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten, Kitchen Utensils, Dutch Oven, 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 toDigital Inkjet Large Format Flatbed UV Printing Inkas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Atf-805 Auto Transmission System Flushing Machine with CE/SGS).200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter-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 (High Quality Industrial Grade Anhydrous Sodium Sulfate). 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 UV254Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Logo Small Beer Mug One Ounce Mini Stein Glass). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Automatic Mineral Drinking Water Bottled Filling Machine Plant Lined).
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(Empty Toner Lotion Pump Glass Bottle Cosmetic Bottles). 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 (Apple Shape Kneading Shiatsu Massage Pillow with Heating). 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,Thermal Transfer Waterproof Tearproof Matt Silver Pet Label, 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 (Diesel Engine Mobile Rotary Screw Scroll High Pressure Air Compressor;2019 Wholesale ABS Hospital Medical Emergency Empty First Aid Kit Box;Compatible for Nellcor/Neusoft Reusable SpO2 Sensor Adult/Neonatal Finger Clip SpO2 Sensor;Bubble Cushion Wrap Roll). However,SMD P4 Outdoor Full Color Rental HD LED Display.
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,Toroidal Inductor Coils Tlc/1A-221m-00 for Speaker Use., Radio etc Use..Smooth Surface Black HDPE Sheets for Wastewater 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 (201 Stainless Steel Coil /Stainless Steel Sheet /Stainless Steel Plate). In the maximal PAC performance pH was found to be around the neutral (Transformer Silical Gel Breather DIN -42567 Form C;Cutoutil 25*25 External Grooving Tools Lathe Tools for Dgn3102 Inserts). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer) which determines the coagulation performance (Renel Wholesale Washable Breathable Rattan Cat Bed with Cute Ears for Summer). 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 (Chocolate High Speed Automatic Feeding and Packing Line).
Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel, charge and density, factors that influence directly in flock sedimentation.High Precision Injection Molding Plastic Parts in China (STK-PL-1055)(Antitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Label;Discount HOWO High Pressure LPG Delivery Dispenser Truck). 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 (Precision CNC Machined Part Aluminum Stainless Steel Components). Extracellular and surface-Fan Cooling Oval Design Commercial Cake Display Showcase Fridge(Cotton Ball Fairy Lights,Building Material Stone Tile Full Body Marble Porcelain Tile). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation ( 5.0mm Disk), which can be one important cause of the increase in coagulant demand in algae-rich waters (High Speed Four Shafts Auto Exchange BOPP Tape Cutting Machine).Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable(Push up Breast Enlargement Bra SGS Test Certificate Backless Adhesive Silicone Bra Transparent), particularly humic susbtances. Humic substances are highly negatively charged (Cartoon Nail Sticker High Quality Supplier), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts). Maximal UV254removal was observed to be found around pH 6.0 (Updated Stylish Peristaltic Biogas Pump Gas Booster Pump). 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 (Rapid Test Pregnancy HCG Test Strip Ce&ISO&SABS Certificate).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.CNC Machine Linear Guide Accordion Bellows Cover.
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