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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 (Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector,China Sink Stopper Manufacturer). As a result, several chemical methods have been applied to control P internal loading worldwide (Good Performance High Precision Thrust Roller Bearing (29292);30% Al2O3 Content Yellow PAC for Wastewater Treatment;ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Deep Drawing 300tons Sheet Metal Stamping Hydraulic Press Machine 100tons, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Aluminium Packaging),Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly. 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 (Precise Profile Wire Universal Rolling Mill;Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant;Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift). However alum may result in high concentration of residual Al and is strongly affected by temperature (Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag) 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 (Herbal Extraction Food Grade Single-Effect Falling Film Thermal Evaporator System). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer;Classic Cafe Dining Chair with High Quality/Grey/Arm Chair;Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould;Cosmetic OEM Gold Pet Foam Bottle for Cosmetic Packaging and Face Cleam;Fastener DIN933 DIN931 Standard Hex Head Cap Screw Black or Zinc Plated M12 M10 Bolt;Automatic Turntable Continouse Blast Cabinets Belt Sandblaster Sandblasting Machine;220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Light).Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line(Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797);High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator;Mj6130ty Precision Sliding Table 45 Degree Wood Cutting Panel Saw;Custom Machining Service Machined Parts High Precision CNC Milling Process) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Large Outdoor Milk Storage Tank), and it has been suggested as a lake restoration measure.
Coagulation-18inch Industrial 3 in 1 Fan-Stand Table Fan, Wall Fan 3 in 1-Competitive Price(Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack) and also by water chemistry (pH and alkalinity) (Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest). 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 (China Loader). At pH of 6.0-7.off-Grid Residential Small Wind Turbine 1kw 12V Generator Kit(Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter,Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect). Algae also can affect coagulation due to characteristics such as morphology, motility,Durable Rectangular FRP Pultruded Grating for Glassfiber Platform(Hotel Dental Kit Toothbrush Shaving Kit Razor Amenities Sets,Permanent N50 Tiny Mini Neodymium Magnet for Sale,Ultrasonic Plastic Welding Machine Manufacturers Cheap Price).
In the tropical semi-Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed-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.55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor. 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
New 14 Inch Diamond Saw Blade for Granite Cutting, 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(Men′s Polyester Moto-Boy Hunting Jacket Clothing) and concentrations of total phosphorus (2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top;Super Large Flesh-Colored Plastic Dildo Female Artificial Sex Machine) 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 (High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015). 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). UV254Fancy Corn Starch Disposable Round Plate with Stripe for Party(DOM), mainly as humic substances (Home Furniture Metal Chair Grey Velvet Dining Chair).
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.)Manhole Cover Stainless Manway Tank Hatch 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 toC1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mmas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Nasal Forceps).Biodegradable Resealable Plastic Food Packaging with Zipper-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 (Stainless Steel Checkered Plate 304 316L 410 Floor Material). 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 UV254Promotion Stock Silicone Tea Infuser for Kitchenware%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Snowkey Meat Processing Cooling Flake Ice Making Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Neoprene Bottle Can Cooler Bag Beverage Storage Carrierd).
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(Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home). 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 (J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter). 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,Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow, 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 (Aluminium Spigot Lighting Truss;Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032);Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060;Air Suspension Component). However,Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light.
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,Stainless Steel Silent Child-Mother Hinge Ball Bearing Hinge for Door Window Hardware Accessories.Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer, 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 (Plastic Roofing). In the maximal PAC performance pH was found to be around the neutral (Good Quality Tungsten Carbide Round Nose End Mill;Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Automatic Food Canning Machine Tin Can Vauum Seamer) which determines the coagulation performance (Cjc1295 with Dac Legit Peptide Hormones for Human Growth). 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 (High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture.
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