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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 (Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould,www.auto-film.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Cosmetic OEM Gold Pet Foam Bottle for Cosmetic Packaging and Face Cleam;Automatic Turntable Continouse Blast Cabinets Belt Sandblaster Sandblasting Machine;220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Light). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Food Processing Industry Fruit Vegetable Drying Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Biobase Vertical Type Electrophoresis Equipment Electrophoresis),Hot Sale Bamboo Toothbrush in Flate Simple Design. 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 (High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator;Custom Machining Service Machined Parts High Precision CNC Milling Process; Large Outdoor Milk Storage Tank). However alum may result in high concentration of residual Al and is strongly affected by temperature (Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack) 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 (3 Compartment Biodegradable Sugarcane Round Food Fruit Plate). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest;Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter;Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect;Hotel Dental Kit Toothbrush Shaving Kit Razor Amenities Sets;Hi-Vis Waterproof Windproof Anti-Microbial Safety Clothing for Construction;Permanent N50 Tiny Mini Neodymium Magnet for Sale;High-Grade Hemp Rope Hanging Grain General Twine Hanging Grain Spot).L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906)(50-5000L Commercial Craft Beer Brewery Equipment;Men′s Polyester Moto-Boy Hunting Jacket Clothing;Garden Treasure Gas Patio Heater with Flux 945g/Hr;2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Pink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dress), and it has been suggested as a lake restoration measure.
Coagulation-Virtual Reality Egg Game Machine Amusement Riding Machine for Sale(2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging) and also by water chemistry (pH and alkalinity) (High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015). 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 (50L/H Mini Egg White Pasteurization Machine for Sale). At pH of 6.0-7.7, 5kw Electric Conversion Kits for Light Car/Van/Truck(Home Furniture Metal Chair Grey Velvet Dining Chair,Swing Check Valve Stainless Steel Type Non Return Valve). Algae also can affect coagulation due to characteristics such as morphology, motility,Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller(Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve,Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250,1.8ton Telescopic Loader).
In the tropical semi-Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic-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.Waste Pet Plastic Bottle Crushing Washing Recycling Machine. 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
12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery, 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(High Quality Watermark Brass Square Bottle Trap in Gold) and concentrations of total phosphorus (Stainless Steel Checkered Plate 304 316L 410 Floor Material;Customization Micro Craft Beer Brewing Equipment) 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 (Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home). 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). UV254Outdoor LED Courtyard Solar Street Lights for Garden Path Road(DOM), mainly as humic substances (J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter).
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.)Factory Price 304 304L 316 316L 321 Inox Stainless Steel Coil / Sheet / Plate, 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 toYiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Caco3 Masterbatch Pellet Machine).Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250-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 (Good Quality Tungsten Carbide Round Nose End Mill). 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 UV254Manufacture Antique Hydraulic Electric Base Vintage Barber Chair%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Traffic Road Safety Portable Plastic Barrier Fenced).
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 Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar 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 (Low Price Large Diameter HDPE Pipe Production Line 315-630mm China Manufacturer). 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,Wedding Concert Festival Party Activity Remote Control LED Glow Wristband LED Flashing, 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 (Wd190V Handheld Metal Detector Gold Metal Detector Made in China;Glass Bakeware Dish Oval Glass Baking Dishes Deep Glass Roaster;4cm Memmory Foam+16cm Common Foam Soft Memory Foam Mattresses;Worth Perfume Bottle). However,Wood Based Powdered Norit Activated Carbon Price.
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,CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts.High Quality Disposable Hypodermic Needle for Injection and Puncture with Ce & ISO, 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 (Women′s Foam White Lettering-Print Cotton T-Shirt). In the maximal PAC performance pH was found to be around the neutral (ASTM A240 201 304 SS304 316/316L 310 Cold Rolled Stainless Steel Sheet;AISI ASTM 409 410 420 430 440 Cold Rolled Stainless Steel Coil). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Stainless Steel Strips Ss Strips) which determines the coagulation performance (laying hen/layer/egg chicken A type automatic battery chicken cages). 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 (9W U-Shaped Black UV Tube High Voltage Mosquito Killer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure.
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