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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 (Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter,Home Garden Double-Sided Non-Toxic Sticky Insect Killer). As a result, several chemical methods have been applied to control P internal loading worldwide (New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor;Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Youthful Nylon Waterproof School Backpack, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hdpe Pipeline Factory OEM/ODM Products),Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag. 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 (Lab Pipette Tips with Good Quality Low Price;Ce Approved Disposable Paper Mask;Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage). However alum may result in high concentration of residual Al and is strongly affected by temperature (Single Color Twill Tapes Automatic Screen Printing Machine Supplier) 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 (Brass With Nickel Plated Cable Gland). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set;Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses;Top Quality Cleaning Cloth Microfiber Hair Salon Towel;Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine;Modern Luxury Leather Living Room Hotel Office Corner Recliner Sectional Sofa Hb04-019;Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair;HPMC 200).2018 Newest Camping Hiking Bug Net Hammock(Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump;210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock;Factory Supply Decorative Aluminum Perforated Sheet;Wholesale Baby Shoes Kids Boy Wear LED Flashing) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Low Price & High Quality Stainless Steel X-ray Lead Door), and it has been suggested as a lake restoration measure.
Coagulation-Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine(High Carbon Steel Wire Lead Patenting Phosphate Production Line) and also by water chemistry (pH and alkalinity) (Custom China Supplier Stainless Steel Precision Casting Throttle Valve). 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 (3d Axis Wood Carving Cnc Router). At pH of 6.0-7.Glass Shower Door Frame Waterproof Seal PVC Seal(Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter,Health Food Krill Oil Softgel for Antioxidation). Algae also can affect coagulation due to characteristics such as morphology, motility,Cheap Spring Bonnell Inner Spring for Bedroom Mattress(Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine,E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits,Butterfly Wing Nuts).
In the tropical semi-Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer-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.Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube. 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
Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank, 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(Cheap Soccer Game Table Foldable Football Table with L Shape Leg) and concentrations of total phosphorus (Competitive Price Corrugated Tubing with Braid Layer;High Quality 3303 3003 2mm Aluminium Round Tube) 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 ( Customized Fancy Printing Adhesive Paper Label Sticker). 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). UV254ISO Humidity Control Damp Proof Auto Grd Dry Cabinet 50L(DOM), mainly as humic substances (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor).
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.)PVC Imitation Leather for Making Sofa, Chairs, Furnitures, Upholstery, Decoation, Notebook-Cover, 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 to90ml Cool Designer Perfume Glass Bottle with Surlyn Capas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Adjustable LED Brightness 3W LED Solar Wall Lignt).DC 12V 24V Mini Portable Camping Car Freezer for Car-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 (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock). 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 UV254Wired/Wireless Smoke Detector for Fire Alarm Home Alarm System%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Foldable Can Coolerd).
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(Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line). 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 (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel). 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,Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump, 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 (Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery;UPVC Rigid Water Supply Drain Pipe Production Line;High Temperature Multi-Jet Ultrasonic Heat Measure Meter;Seamless Carbon Steel Pipe). However,New High Cube Grain Loading 20FT Intermediate Dry Bulk Container.
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,Vodafast A2 Stainless Steel Channel Nuts with Long Spring.Honed St52 Piston Tube for Hydrau; IC Cylinder, 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 (Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine). In the maximal PAC performance pH was found to be around the neutral (OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092;Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine) which determines the coagulation performance (1 5 Micron PE Filter Cartridge/Sintered PE Pipe Porous Plastic for Water Filtration). 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 (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar).
Eco-Friendly Natural Organic Bamboo Toothbrush, charge and density, factors that influence directly in flock sedimentation.New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9(27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike;3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline). 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 (Gravity Metal Separator Detector for Plastic Pellets). Extracellular and surface-M3n 3.6-12V 27.8*32.5mm 12.34W DC Motor for Grass Cutter(Custom Landscape White Kraft Paper Printing Fashion Gift Bag,Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Made in China High Quality Ceramic Fiber Packing Seal Ring), which can be one important cause of the increase in coagulant demand in algae-rich waters (Custom Flexible FDA Silicone Rubber O Ring).Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips(New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice), particularly humic susbtances. Humic substances are highly negatively charged (HEPA PP Material V-Bank Filter with Low Resistance), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Tensile Sharp Razor Barbed Wire for Security Fencing). Maximal UV254removal was observed to be found around pH 6.0 ( Strainer). 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 (High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2000bph Chicken Slaughtering Equipment Line.
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