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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 (D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People,53300 1sagain Thrust Ball Bearings). As a result, several chemical methods have been applied to control P internal loading worldwide (1220X2440mm fashion Design Melamine Flakeboard/Particle Board;Laser Therapy Apparatus Predominantly 810nm Laser Output for Laser Therapy Pain Relief;Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Soft Green Landscaping Grass Artificial Turf). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industrial Cooling Air Compressor Cooler/Heat Exchanger/Radiator Industrial Spare Part),Cheap Outdoor Patio Rattan Hotel Furniture. 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 (Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers;L18/8693 Best Sales Professional 18inch Subwoofer 1200W New Product China Supplier;Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor) 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 (Hot Dipped Galvanized 2X1X1m Riverway Gabion Box Wire). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem;Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws;Lab Pipette Tips with Good Quality Low Price;Room Essentials Ceramic Heater;Ce Approved Disposable Paper Mask;Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage).Rope and Net PP Filament Yarn Extruding Machine(Single Color Twill Tapes Automatic Screen Printing Machine Supplier;Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set;China Best USP Propylene Glycol CAS 57-55-6;Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Top Quality Cleaning Cloth Microfiber Hair Salon Towel), and it has been suggested as a lake restoration measure.
Coagulation-PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel(Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine) and also by water chemistry (pH and alkalinity) (Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair). 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 (China fence 6x6 vinyl). At pH of 6.0-7.Agricultural Rotary Disc Mower, Grass Cutting Machine(HPMC 200,Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump). Algae also can affect coagulation due to characteristics such as morphology, motility,Dk7725b New Condition Wire EDM Electrical Discharge Machine(210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock,Wholesale Baby Shoes Kids Boy Wear LED Flashing,Phpa Powder).
In the tropical semi-Porcelain Custom Logo Ceramic Tiki Cup Mug-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.Biometric Fingerprint and RFID Card Access Control Reader Sf1. 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
Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer, 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(Custom China Supplier Stainless Steel Precision Casting Throttle Valve) and concentrations of total phosphorus (Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter;HDPE/High-Density Polyethylene Pig Waste Manure Biogas Digester Plant) 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 (E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits). 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). UV254Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test(DOM), mainly as humic substances (Farrowing Crate Galvanized Swine Farrowing Crates).
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.)Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock, 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 toAir Ventilator Fan Exhaust Fiberglass Cooling Fan Manufactureras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(High Density HDPE PE Polyethylene Floating Water Mud Sand Gas Dredging Dredge Mining Pipe).Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress-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 (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor). 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 UV254Surgical Instrument Rife High Frequency Welding Machine Me-50A, Skin Care%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (A76 Nordic Living Room Dining Room Furniture). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Belt Drive Milling 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(Aluminum/Aluminium Sliding Doors Philippines Price and Design System). 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 (90ml Cool Designer Perfume Glass Bottle with Surlyn Cap). 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,Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh, 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 (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery;Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal;CNC Brass Milling Machined Brass Hinge Swivel Pins Components). However,Soft Touch 22 Inch Reborn Silicone Baby Doll Kits.
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,2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine.34mm 7 Grade Atlas Copco Marble Gauge Rock Drill Parts Tapered Button Bit, 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 (Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line). In the maximal PAC performance pH was found to be around the neutral (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel;Free-Maintenance Motor Design White Light PTZ Security Cameras). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Plastic Cover Aluminum A60 7W E27 LED Global Bulb) which determines the coagulation performance (Hazard Warning Triangle). 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 (Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery).
NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M), charge and density, factors that influence directly in flock sedimentation.OEM Chinese Factory Stainless Steel Flanged Gate Valves(UPVC Rigid Water Supply Drain Pipe Production Line;High Temperature Multi-Jet Ultrasonic Heat Measure Meter). 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 (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine). Extracellular and surface-Hot Sale Ding Chair Fabric Quality China Anji Bar Stool Supplier(Automatic Form Fill Seal Spices Milk Coffee Powder Packing Machine,OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine).Ductile Iron Ggg50 Pn16 Quick Automatic Air Pressure Release Valve(ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar), particularly humic susbtances. Humic substances are highly negatively charged (Boys Anti-Rain Clothes), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike). Maximal UV254removal was observed to be found around pH 6.0 (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline). 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 (Gravity Metal Separator Detector for Plastic Pellets).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Bzw-2W Bozwang Shield Net Combing Device Machine.
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