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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 (A76 Nordic Living Room Dining Room Furniture,Vhf Transmitter). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body;Aluminum/Aluminium Sliding Doors Philippines Price and Design System;90ml Cool Designer Perfume Glass Bottle with Surlyn Cap). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2.5hp 3hp 5hp Direct Air Compressor),Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75. 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 (Fr-218 BOPP Packing Tape Slitting Rewinding Machine;Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). However alum may result in high concentration of residual Al and is strongly affected by temperature (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal) 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 (Lastic Scoop Measuring). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line;Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel;Free-Maintenance Motor Design White Light PTZ Security Cameras;Plastic Cover Aluminum A60 7W E27 LED Global Bulb;Gaming Chair Racer Sport with Lumbar Support Furniture Black Gamer Chair Blue;Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery;UPVC Rigid Water Supply Drain Pipe Production Line).New Version Breakage-Proof Multihead Weigher for Biscuits(High Temperature Multi-Jet Ultrasonic Heat Measure Meter;Electric Spray Machine Wall Spray Plaster Machine / Mortar Spraying Machine;Organic Cotton Pillowcase;OEM High Quality Stainless Steel Ladies Anolog Wrist Watch Jewelry Diamond Watch 71092) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)), and it has been suggested as a lake restoration measure.
Coagulation-Log Debarker Veneer Rotary Peeling Machine(Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine) and also by water chemistry (pH and alkalinity) (ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar). 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 (www.kkwcosmetic.com). At pH of 6.0-7.IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor(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 also can affect coagulation due to characteristics such as morphology, motility,DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval(Gravity Metal Separator Detector for Plastic Pellets,Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002,Protective Sun Hat).
In the tropical semi-Portable Solar Lantern with Built-in Solar 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.Asphalt Pavement Bitumen Road Crack Seal Equipment. 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
Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss, 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(New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice) and concentrations of total phosphorus (High Tensile Sharp Razor Barbed Wire for Security Fencing;Stainless Steel Hexagon Shaft) 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 (Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve). 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). UV2543 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer(DOM), mainly as humic substances (Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag).
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.)2019 Bdu Army Camouflage Uniform with 3-Color Desert Color, 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 toStainless Steel Metal Spiral Conveyor Belt Mesh Band for Ovenas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hotel Specific Air Fresheners Beautiful Ceramic Stone Aroma Diffuser).Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery-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 (Low-Cost Tree Stump Crushing Machine with Widely Using). 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 UV254High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Plant Stands & Accessories Glass Hanging Flower Pot Bracket). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pu Wheel Forkliftd).
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(Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z). 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 (Lightweight New Design Girl Fashion Bags Children School Backpack). 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,Stable Steel Flat Glass Transport Rack with Safe Support Protection, 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 (Round 10W LED CCT Tuneable Dimmable Down Lights;Customize Cartoon Printing Logo Brand Silicone Swim Cap; Citycoco;chinapucornice). However,Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine.
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,Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym.35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck, 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 (Type F High-Rise Clip Drive/Worm Hose Clamp). In the maximal PAC performance pH was found to be around the neutral (28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket;New Version Breakage-Proof Multihead Weigher for Biscuits). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (S14-M 30~1600kVA (10KV) Oil Immmersed Distribution Transformer) which determines the coagulation performance (Two Sides Full Printing Logo Design Printed Paper Packing Bags). 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 (FDA Approved Custom Eye Mask Packaging Bag / Mylar Foil Facial Mask Pouch / Cosmetic Cream Sachet).
Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe, charge and density, factors that influence directly in flock sedimentation.Fertilizer Binder and Dispersant Sodium Lignin Sulfonate(European Type 7 Pin 13 Pin 12V 24V Brass Contact Truck Vehicle Trailer Plug Socket;Zumex Style Speed Tank Podium Commercial Citrus Juicer). 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 (CNC Metal Fiber 2000W Laser Cutter with Switching Working Table). Extracellular and surface-Reducer Hydraulic Fitting with Swivel Nut (2D)(Scaffolding Timber Plank Pine LVL Plywood From Linyi Supplier,Unistrut Type Slotted Steel Strut Channel or C Channel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder), which can be one important cause of the increase in coagulant demand in algae-rich waters (1000W Electric Motor Price Lawn Mower Motor Concrete Mixer).Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable(Modern design Prefab Steel Structure Livestock Farm for Layer Chicken and Broiler), particularly humic susbtances. Humic substances are highly negatively charged (Jinan CO2 Laser Cutter Cloth Fabric CO2 Laser Cutting Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials). Maximal UV254removal was observed to be found around pH 6.0 (Surgical Drape Angio Pack Angiography Drape Pack). 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 (Synthetic Fiber Filter Rolls Filter Media for Air Conditioning).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine.
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