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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 (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131,1200W Electric Portable High-Quality Jet High Pressure Washer/Cleaner). As a result, several chemical methods have been applied to control P internal loading worldwide (Home Security Video Door Phone Camera Doorbell Intercom System for Villa;White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem;Natural Wave Brazilian Virgin Human Hair Extension). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PLC Control Multi Layer Rubber Tile Plate Vulcanizer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Jewelry Blank Bangles),Broadband Dielectric Coated Right Angle Mirrors. 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 (5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD;AAC Block Making Machine Line Supplier/AAC Block Machinery;Custom Promotional Soft Cover Children Music Book Printing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale) 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 (Stainless Steel Mesh Strap Men Watch Quartz Movement Alloy Case). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cardboard CO2 100W Tube Tube Laser Cutting Machine;a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a;Replacement EPE Eppensteiner Filter Element (8260P10S000P);Stainless Steel High Quality Cashier Counter Table for Shopping Center;Giantmay Professional Beverage Display Energy Drink Stand Shelf Metal Basket;4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System;Hot Runner High Precision Plastic Injection Mold for Household Home Appliance).Aluminium Profile Wood Color Tilt and Turn Casement Windows and Stainless Screen Doors(Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W;Customized Corrugated Kraft Paper Box Mailing Cardboard Shipping Boxes;Best Dry Cabinet Brand;2018 Hot Selling Gold Stainless Steel High Bar Chair) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Carbon Steel Solar Bracket for Flat Roof Mounting System), and it has been suggested as a lake restoration measure.
Coagulation-Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup(Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet) and also by water chemistry (pH and alkalinity) (Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench). 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 (Pet Yarn Making Machine). At pH of 6.0-7.China New Technology Swimming Pool Heat Pump (MDY50D)(Strong Block Permanent NdFeB Magnet for Motor Application,New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds). Algae also can affect coagulation due to characteristics such as morphology, motility,12mm LED RGB String Light/ LED Pixel with SD Card Controller( Telehandler Price,Automatic Pesticide Bottle Blowing/Making Machine,Cable Rod Architectural Mesh).
In the tropical semi-Custom Printed Summer High Quality Rubber Flip Flops Slipper Manufacturer-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.Divan Modern Sofa Set U Shape Leather Sofa with Acoustics. 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
Eboattimes Factory OEM Flavor Mint E Juice Nic Salt 50mg E Liquid, 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 Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts) and concentrations of total phosphorus (Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution;Ceramic Tile Bathroom Floor) 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 (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine). 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). UV254Water Jet Cutting Machine CNC Machine Spare Parts UHP Seal Assembly Part No. 014597-1(DOM), mainly as humic substances ( 24-380VAC Single Solid State Relay).
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.)Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price, 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 toComfortable Pillow Top Latex Pocket Spring Coil Hotel Mattressas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Custom Nylon Spandex Women Pants Blank Yoga Pants).High Visibility Reflective Safety Waterproof Outdoor Winter Jacket Softshell Jacket-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 (Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019). 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 UV254Wooden Grain Siding Plank for Villa Integrated House%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Design Artificial Leather Fabric PVC Leather for Furniture (1008#)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (White Melamine Paper Faced Blockboard /18mm Poplar Core Blockboardd).
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(Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275). 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 (Blackboard Imprint Unique Glass Drinking Jars for Canning). 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,Power Cables C13 C14 Connector Power VDE, USA, RoHS Certificated, 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 (Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine;High Quality Custom Design China Plastic Injection Molding Factory;side table modern). However,Real-Time GPS Padlock Container Tracker GPS Tracking Car/Truck Fleet Management.
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,High Efficiency Hook Type Shot Blasting Machine for Sale.Wallbox Socket Type 2 32A 22kw Three Phase EV Charger for Smart Charge, 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 (Pre-Heated Copper Coil Pressure Solar Water Heater Equipment). In the maximal PAC performance pH was found to be around the neutral (Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale;Hot Selling SAA Rcm Listed CCT Changeable LED Down Light). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Microblading Supplies Private Label Disposable Tattoo Pen Eyebrow Manual Pen with Blades) which determines the coagulation performance (Truck Crane 35 Ton). 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 (Factory Manufacturer 100 Ml Cosmetic Lotion Perfume Plastic Pet Bottle).
Locksmiths′ Klom Professional Unlocking Tools, charge and density, factors that influence directly in flock sedimentation.Od115mm Two or Three Layers Diamond Tuck Point Blade(20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screen;Manufacturers Supply Through Hole Right Angle USB 1394 Connectors). 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 (Silk Dome Horn Speaker Tweeters 2 Pair for Car Stereo). Extracellular and surface-AISI 304 316L 309S 317L 321 904L 421 Stainless Steel Strip(Air Compressor Polyurethane Hose with Quick Coupler,Factory Directly Sale Virgin Kraft Liner Paper Machines). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Special Offer Stock Primary School Uniform Shirt for Boys), which can be one important cause of the increase in coagulant demand in algae-rich waters (12V200ah Cspower High Temperature Deep Cycle Solar Gel Battery).CNC Machining Aluminum/Stainless Steel/Copper Filler Necks Flanges(Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult), particularly humic susbtances. Humic substances are highly negatively charged (Ab Roller For Sale), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts). Maximal UV254removal was observed to be found around pH 6.0 (Small Lab Model Making Home Personal Desktop off-Line Printing Chinese 3D Printer). 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 (Aol CNC 1625 Cutting Plotter for Corrugated Cardboard).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Plastic PVC/WPC Granulator Die Face Cutter Extruder Machine.
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