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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 (Ci/Di/Ss/C954 Al Bronze Body Double Flange Butterfly Valve Pn10 Pn16 Pn25,Electric Weeder Machine Suppliers for Sale). As a result, several chemical methods have been applied to control P internal loading worldwide (Modular Concrete Batching Plant by Twin Shaft Mixer 3000/2000;Virtual Reality Egg Game Machine Amusement Riding Machine for Sale;Ad-P720 Hot-Selling Perfume Glass Bottle 100ml). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,EPS100 Nts100 Xns100 Common Rail Injector Test Bench, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Wholesale Cheap Strong Wedding Party Event Clear Crystal Plastic Resin Acrylic Chiavari Chair),High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration. 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 (Hidrotek Water Filter Cartridge with Sediment Carbon;9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting;Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Diesel Fuel Leak off Pipe for Mercedes-Benz) 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 (One of Hottest for Free Cms Software Tracking System Ssd Mdvr 4 Channel - 4CH SD CARD DVR SYSTEM - TOPO ). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Plastic Pet Preform Injection Moulding Machine Price;High Quality Polyurethane Adhesive for Scrap Sponge;Carbon Steel Carry Idler Belt Conveyor Guide Roller;Rexroth Hydraulic Pump A8V55/80/107 Replacement Spare Parts;20 Liter Jar Filling Machine;Factory Supply Customized Sintered Inner Gear Rotor by Iron Alloy Powder;2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card).ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe(Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire;High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling;Top Quality Grooved Pipe Joint Short Grooved 90 Elbow Cost;ASTM A792 PPGI PPGL Roof Sheet Cold Rolled Steel Coil) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Modular Functional L Shape Living Room Leather Sofa), and it has been suggested as a lake restoration measure.
Coagulation-LED Dancing Wing Props Halloween Christmas Party Supplies(Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone) and also by water chemistry (pH and alkalinity) (High Quality CNC Turning Center Parts Machinery Auto Parts). 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 (Chrome Nail Powder). At pH of 6.0-7.AAC Autoclaved Aerated Concrete Brick Making Machine, AAC Plant Solution(Factory Price Gerneral Usage Silicone Sealant,Transparent 240W SMD 3030 Outdoor LED Flood Lamp). Algae also can affect coagulation due to characteristics such as morphology, motility,15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB(ISO Factory of Disc Cutter for Tunnel Boring Machine,CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut,High Quality Galvanized Pan Head Self Drilling Screw).
In the tropical semi-Auto Crane Electrical Overhead Cable with Steel Wire-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.Safety Bike for Cool Design Children Bike/Bicycle. 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
CCTV Security System Projects IP Camera Factory Hikvision IP Camera, 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(Dac34640037 Wheel Bearing /Automotive Bearing/ Hub Bearing) and concentrations of total phosphorus (Aluminum CNC Al5052 / Al6061 / Al6063 Machining Turning Parts for Mil-Spec Electronics;HSS M42 Bi-Metal Band Saw Blade for Steel) 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 (2019 Henan Factory Manufacturer Industrial Wood Chipper Wood Chipper Shredder). 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). UV254Eco-Friendly Euro Plastic Container with Lid(DOM), mainly as humic substances (Banbury Rotors 3L Lab Plastic and Rubber Mixer Machine).
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.)2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′, 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 toAluminum/Aluminium Foil/Coil for Retort Pouch/Bag/Stand-up Pouch A8079/1235/8011-Soft 5.9/6 Micronsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Double Union Electric Valve).Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights-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 (Full Automatic Egg Tray Manufacturing 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 UV254Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality and Cheap Mobile Phone LCD Touch Screen for Huawei Enjoy 8 Plus /Y9 2018d).
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(LPG Filling Station (Volume Optional) Gas Station with Dispenser Mobile LPG Skid Mounted). 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 (CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts). 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,Standard Air Small Sandblaster for Construction Machinery Cleaning, 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 (Hot Selling Construction Machine 50cbm/H Ready Mixed Concrete Mixing Plant;Metal Enclosure Withdrawable Distribution Switchgear Cabinet Low Voltage;Individually Wrapped Paper Straws Compostable Paper Drinking Straws;Scrap Tire Production Line to Rubber Powder Tire Crumb Rubber Recycling Machine). However,Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,.
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,Customized Dust Filter Cartridge Price for Industrial Welding Fume.Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds, 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 (10ml Plastic and Glass Small Travel Perfume Bottle). In the maximal PAC performance pH was found to be around the neutral (Factory Price 1100 Aluminum Disc Discs Circle Round Plate;Bsg-901 High Quality Cheap Price Soccer Goal Nets). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Galvanized Steel Concrete Nail Use for Construction) which determines the coagulation performance (Engine Cylinder Head Valve Chamber Cover for Volkswagen Polo 1.4 036103473K). 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 (Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing).
Standard Sizes Aluminium Galvanized Mild Steel U Channel, charge and density, factors that influence directly in flock sedimentation.Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood(Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel;Shanghai Port Adjustable Steel Hinge for Security Wooden Door). 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 (Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price). Extracellular and surface-Rubber Raw Material Kneader Machine -75L Banbury Mixer(Presses Seal,PLC Control Multi Layer Rubber Tile Plate Vulcanizer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup), which can be one important cause of the increase in coagulant demand in algae-rich waters (Round Silicone Rubber Desk Grommet / Nylon Plastic Cable Management Organizer).Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment(Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan), particularly humic susbtances. Humic substances are highly negatively charged (Dental Package Box /Denture Box with Membrane/Jewelry Box), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Healong Company Customized Soccer Jersey for Club). Maximal UV254removal was observed to be found around pH 6.0 (Poultry Farming Equipment Chicken Cage for close farming house Automatic design). 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 (CNC Forging Motorcycle Aluminum Chain 520 Sprocket).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML).
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