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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 (10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps,Double Stick Tape). As a result, several chemical methods have been applied to control P internal loading worldwide (Prefab Multifunctional Steel Structureg for Wholesales Construction Material; Paper Bags;A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (304 Stainless Steel Pipe Manufacture in China). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Aluminum Anodizing Anodized CNC Turning Machining Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (1 Inch Display Wholesaler Quotes & PriceList),2 Head Embroidery Machine Cap Flat T Shirt Embroidery. 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 (Hospital Equipment 23L Benchtop Autoclave;Light Controller DMX Controller for Stage Light;Alluvial Sand Tin Mining Process Equipment Rollers Electrostatic Separator). However alum may result in high concentration of residual Al and is strongly affected by temperature (Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers) 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 (Aluminum Melting Crucible). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Fasion Style Custom Indian Embroidery Patch;Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor;Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt;Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C;Content Labels Dyeing And Finishing Machine;Plastic Reflective Raised Pavement Marker Road Stud;Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style).High Quality Plastic Bulk Dry Food Dispenser Single Cereal Candy Dispenser for Sale(PU Foam Plastic Squishy Slow Rising Toy for Unicorn;Top Quality Polar Wohlenberg Paper Cutting Blade;Ceramic Art Tile;Large Format Auto Open Heat Press with Slide-out Press Bed) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava), and it has been suggested as a lake restoration measure.
Coagulation-Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb)(Public Address System High Power Range Outdoor Column Speaker) and also by water chemistry (pH and alkalinity) (Automatic Multi Station Nut Forging Machine/Nut Cold Forging Machine). 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 (Counter Roller for The Rack for Gjj and Baoda Passenger Hoist). At pH of 6.0-7.Heavy Duty High Chrome Sand Dredger Mining Tailing Slurry Pumping Machine for Chrome Mining(Water-Proof Silicone Coated Fiberglass Cloth,Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace). Algae also can affect coagulation due to characteristics such as morphology, motility,1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire(98% Polypeptide Hormones CAS 113-79-1 Argpressin Acetate as Neurotransmitter,Custom Polyester Woven Patch Logo Snapback Hats,Galvanized Floor Grating).
In the tropical semi-High Quality Industrial Grade Anhydrous Sodium Sulfate-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.LSR Injection Mold Tooling for Medical Nipple. 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
Wholesale Promotional Children Painting Apron, Child Apron, Kids Apron, Disposable Nonwoven Apron, 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(Self Tapping Screw Roofing Screw Bimetal Screw) and concentrations of total phosphorus (Double Side Painted Aluminium Coil Plate with PE Film;Electric Disabled Helper Ce Elder Using Handicap Vehicle Four Wheel Mobility Scooter) 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 (Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles). 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). UV254100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer(DOM), mainly as humic substances (Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover).
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 New Factory Direct Metal Bird Feeder for Garden Decoration, 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 toIndustrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabricas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Small Bushing).Manufacturers Wholesale Microfiber Car Cleaning Towel-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 (9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion). 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 UV254Gdg24 0.55kw 550W 0.75HP 24L Oil Free Air Compressor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Li/Lithium LiFePO4 32650 Battery 3.2V for Solar Ess EV Electric Vehicle 5000mAh 6000mAh/6ah 6500mAhd).
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(High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging). 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 (Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720). 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,Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP), 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 (Best Polystyrene Sandwich Board Manufacturer;High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping;Customized Microfiber Sport Towel for Swimming Towel;hongxin-ec.com). However,3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker.
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,Best Factory Price Metallic Honor Medal with Neck Ribbon.Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China, 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 Small Module Sintered Metal Product Spur Gear Pinion). In the maximal PAC performance pH was found to be around the neutral (Wg9130583017 Sino Truck Spare Parts Combination Switch;Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Waterproof Magnesium Oxide False PVC Ceiling Panel) which determines the coagulation performance (Factory Supply Organic Fertilizer with NPK Black Particles Fertilizer). 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 (Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.PVC Gas Hose, LPG Hose Best Choice for Home Use.
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