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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 (Fabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003),China Focused Ultrasound). As a result, several chemical methods have been applied to control P internal loading worldwide (Snowkey Manufacture Best Selling Air/Water Cooling Tube Ice Making Machine;ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar;27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fire Retardant Aluminium Composite Panel),Industrial Air Cooled Heat Pump Water Chiller in Many Field. 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 (Gravity Metal Separator Detector for Plastic Pellets;Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002;Made in China High Quality Ceramic Fiber Packing Seal Ring). However alum may result in high concentration of residual Al and is strongly affected by temperature (Custom Flexible FDA Silicone Rubber O Ring) 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 (Airport Mesh Fence Suppliers/Manufacturers for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (New Design Crown Caps 60ml Pet Plastic E Liquid Bottles E Juice;High Tensile Sharp Razor Barbed Wire for Security Fencing; Strainer;High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head;Feed Additive Amino Acid Powder 70% (Crude Protein more than 110%);Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve;Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag).Building Material Colorful Stone Coated Metal Spanish Roofing Tile(Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens;Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel;Bs464 Thimbles;Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven), and it has been suggested as a lake restoration measure.
Coagulation-Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid(Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype) and also by water chemistry (pH and alkalinity) (Automatic Mango Juicer Filling Machine / Canned Juice Production Line). 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 (Double Side Solar Road Reflector Suppliers for Highway Safety). At pH of 6.0-7.Sculpture Wood Carving CNC Router Machine Engraver(Low-Cost Tree Stump Crushing Machine with Widely Using,Plant Stands & Accessories Glass Hanging Flower Pot Bracket). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory(Seamless Circular/Square/Rectangular Steel Tube,Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z,2019 PP Ecological Bag Used for Slope Planting).
In the tropical semi-Mechanical Seal with All Metal Parts, Equivalent to Flygt Seal-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.Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service. 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
Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style, 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 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price) and concentrations of total phosphorus (Round 10W LED CCT Tuneable Dimmable Down Lights;SS316 SS316L Powder Sintered Filter Cartridge for Liquid Filtration) 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 (Type F High-Rise Clip Drive/Worm Hose Clamp). 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). UV254Aluminum Oxide Abrasive Products 5 6 Stone Metal Disc Grinding Wheel(DOM), mainly as humic substances (28L Wholesale Retail Plastic Basket Chinese Suppliers Supermarket Shopping Large Basket).
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.)Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control, 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 toEuropean Type 7 Pin 13 Pin 12V 24V Brass Contact Truck Vehicle Trailer Plug Socketas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Large Retractable Dog Leash 8m).Wholesale Sport Wear Mens Gym Running Polyester T Shirt-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 (Unistrut Type Slotted Steel Strut Channel or C Channel). 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 UV254Potato Chips Design Non-Toxic Silicone Baby Teether Toy%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (5kn Electronic Adhesive Tensile Compression Shear Peel Strength Testing 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(Modern design Prefab Steel Structure Livestock Farm for Layer Chicken and Broiler). 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 (Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials). 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,Audley Automatic 63′′ Hot and Cold Roll Paper Laminator Machine Price Adl-1600h5+, 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 (Must 4kw 2HP Pump Power Inverter Ags Bts Available;Prefab Factory Price High-Quality Modern Shipping Container Clinic;Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion;Flat Irradiation UV Curing Machine/UV Coating Machine). However,Flexible High Pressure Nitrile Magic Hydraulic Rubber Hose in UAE for Oil Fuel, Water, Air.
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,Quick Charger 18W USB-C Pd Charger for iPhone11.China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card, 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 (Customized Dummy Animal Teething Toy Design Baby Pacifer). In the maximal PAC performance pH was found to be around the neutral (KERONG Electronic Keypad Digital Combination Hardware Glass Locks For Lockers′ Safes;High Purity Calcined Alumina Micro Powder for Ceramics Refractories). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Kids Waterproof Cow Leather Wool Felt Warm Fur Boots for Winter) which determines the coagulation performance (Central Tube GYXTW 4 Core Singlemode Fiber Optic Cable). 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 (Coating Precision CNC Auto Spare Machinery Parts Turning and Milling Industry).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Motorized Automatic Electric Roller Shutters Window, Aluminum Hurricane Rolling Shutter.
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