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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 (Water Park Outdoor Playground with Water Spray Device for Sale,Liquid Silicone Rubber). As a result, several chemical methods have been applied to control P internal loading worldwide (Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift;1/2 Inch Brass Stem Handwheel Gate Globe Valve;Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Aol CNC 1625 Cutting Plotter for Corrugated Cardboard, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Blind Rivets Assortment Manufacturers Cheap Price),Wholesale Room Ozone Generator for Fruits and Vegetables. 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 (Waste Pet Plastic Bottle Crushing Washing Recycling Machine;Glass Mike Bottle 200ml 250ml with Screw Cap Straws;Liquid Laundry Detergent Small Single Bag Packing Machinery). However alum may result in high concentration of residual Al and is strongly affected by temperature (2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part) 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 (Advertising Outdoor LED Large Screen Display P10 Full Color Programmable LED Sign). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug;Semi-Automatic Hydraulic Leather Football Machine;15 Inch IP65 Waterproof Industrial Touch Screen Monitor;Modern Style Prefabricated Steel Structure Poultry House;Goat Panels; Splicing Machine S6;Double Deck High Quality Aluminum Pontoon Boat for Sale).Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack(Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885);Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes;LED Light Flexible Printed Circuit Board and LED Rigid PCB;Floor Mounted Glass U Clamp Channel for Glass Balustrade) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality Curve Spear Tunnel Bolt for Concrete Ring), and it has been suggested as a lake restoration measure.
Coagulation-Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens(Brand New Forklift with Double Front pneumatic Tire) and also by water chemistry (pH and alkalinity) (Automatic Small Round Bottle Water Washing Filling Capping 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 (Automatic Small Round Bottle Water Washing Filling Capping Machine). At pH of 6.0-7.Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine(MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration,3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor). Algae also can affect coagulation due to characteristics such as morphology, motility,OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated(Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods,White/Gray Colors U-PVC Water Supply Pipe for Plumbing System,Abrasive Zirconia Fiber Disc for Metal Sanding and Polishing).
In the tropical semi-LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031-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.CNC High Speed Gear Hobbing Machine Ys3118CNC5. 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
Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group, 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(Na2co3 Soda Ash Sodium Carbonate Food Grade) and concentrations of total phosphorus (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag;Eco Friendly Clear Glass Water Bottles Portable Sport Drinking Tea Bottles with Bamboo Lid) 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 (Hydraulic Metal Hole Digger Punching Machine (CH-80)). 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). UV254CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router(DOM), mainly as humic substances (Factory Customized Marathon Athletics Football Awards Medallion Metal Medal).
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.)Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts, 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 toHot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Rideas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Baby Car Seat China).Auto Starter 0001230002 12V 3.0kw 11t for John Deere-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 ( Grass Cutting Machine). 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 UV254High Speed Double Jersey Computerized Transfer Rib Circular Knitting Machine 2/3 Ways Djjtr%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hexagon Socket Mushroom Head Bolts with Factory Pricesd).
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(Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)). 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 (ANSI B16.5 Stainless Steel SS316 Forging Blind Flange). 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,Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove, 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 (Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover;Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5);China Cup Set Handmade Coffee Cup and Saucer Set;Sparrow Net). However,Plastic Traveling Pet Crate Dog and Cat with Wheels and Handle Travel Cage.
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 Galvanized Perforated Metal Sheets.Stainless Steel Sanitary Rectangle Manway with Two Intersectant Arms (CD-mc2997), 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 (NEMA IP65 Wall Mount Electric Metal Cabinets). In the maximal PAC performance pH was found to be around the neutral (60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400;Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hight Quantity Micropore Tfc-3012-300gpd RO Membrane) which determines the coagulation performance (Commercial Sewage and Sea Water Source Screw Heat Pump Chiller). 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 (4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials.
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