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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 (LED Mounter Jx-300LED/ Chip Shooter/ Jx300LED Mounter,Foshan Factory Cinema Church Folding Leather Fabric Auditorium Chair). As a result, several chemical methods have been applied to control P internal loading worldwide (New Design Comfortable PU Cemented Men and Boy Sandal;Best Plastic Water Bottle 750ml Tritan Drinking Bottle;10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (D09 Lightweight Foldable Lithium Battery Electric Wheelchair for Elderly People). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ci/Di/Ss/C954 Al Bronze Body Double Flange Butterfly Valve Pn10 Pn16 Pn25, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cnc Precision Drilling Machine Parts),Miniature Linear Motion Guide Mgn5/Mgn7/Mgn9mgn12/Mgn15 Square Linear Block. 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 (1220X2440mm fashion Design Melamine Flakeboard/Particle Board;Laser Therapy Apparatus Predominantly 810nm Laser Output for Laser Therapy Pain Relief;Zero Spangle Gi Steel 2mm 1500mm Galvanized Iron Sheet Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Soft Green Landscaping Grass Artificial Turf) 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 (Customized Cheap Iron Fashion Simple Tie Bar for Decoration (005)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers;L18/8693 Best Sales Professional 18inch Subwoofer 1200W New Product China Supplier;Heavy Duty Permanent Magnet Lifting Hoist Magnetic Crane Lifter;New Type High Pressure Italy Permanent Magnet Oil Free Screw Air Compressor;Drainage Steel Grating Cover Drainage Ditch;Hot Product Long-Life Conveyor Roller for Conveyor System (dia. 159);Factory Price of Potassium Hydroxide (KOH) Flakes 90%Min Purity -Qingdao Hiseachem).Hot New PC Polarized Sunglasses Manufacturers Direct(Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws;Lab Pipette Tips with Good Quality Low Price;Army Military Quartz Mens Watches Top Brand Luxury Casual Sport Leather Men Watch #V554;Ce Approved Disposable Paper Mask) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage), and it has been suggested as a lake restoration measure.
Coagulation-China Gingseng Extract Ginsenosides 15% 20% 80%(Single Color Twill Tapes Automatic Screen Printing Machine Supplier) and also by water chemistry (pH and alkalinity) (Amazon Hot Sale 10 Inch / 12 Inch / 15 Inch Pre-Seasoned Cast Iron Skillet Pan Set). 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 (3 Axis Any Angle Aluminium Profile Double Head Cutting Saw). At pH of 6.0-7.New Baking Tool Creative Customized Silicone Toast Cake Mold(Double Cylinder Multi-Head Deep Draw Metal Stamping Hydraulic Presses,Top Quality Cleaning Cloth Microfiber Hair Salon Towel). Algae also can affect coagulation due to characteristics such as morphology, motility,Disposable TPE Gloves, Plastic TPE Gloves, TPE Gloves(Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine,Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair,Barbecue Stainless Steel Crimped Wire Mesh for Japan/Korea).
In the tropical semi-Hot Sale Pet Strap Straps Strapping Band Machine/Extrusion Line/Extruder-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.Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels. 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
Gas Sniffer with City Sensor for CH4 Methane Produced by Wall-Mounted Gas Detector Supplier, 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(210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock) and concentrations of total phosphorus (Wholesale Baby Shoes Kids Boy Wear LED Flashing;Stainless Steel Spiral Duct for HVAC Ductwork) 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 (Custom China Supplier Stainless Steel Precision Casting Throttle Valve). 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). UV254Naked Mango Premium E-Liquid for Electric Cigarette(DOM), mainly as humic substances (Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter).
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.)1.5M/2M/3M Cheap Quality Government Office meeting room pole stand Flag, 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 toFarrowing Crate Galvanized Swine Farrowing Cratesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Underwater Submersible Jet Aerator for Aeration and Pond Oxygenation).Popular Environmental Plastic Vinyl Spc Floor Tile-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 (Competitive Price Corrugated Tubing with Braid Layer). 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 UV254AC 24V 400W Verical Axis Wind Turbine (SHJ-NEV400S)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cheap PriceList for Floor Stand Digital Signage - NORMAL CAMERA - TOPO d).
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( Customized Fancy Printing Adhesive Paper Label Sticker). 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 (TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor). 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,XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator, 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 (Aluminum/Aluminium Sliding Doors Philippines Price and Design System;90ml Cool Designer Perfume Glass Bottle with Surlyn Cap;Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle;Dia. 35mm Abl Tube Suppliers Cream Packaging Tube). However,SMD Sport Headband Knitted Beanie Cr2032 Lithium Battery Winter Headband Hiking Lamps.
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,Hydraulic Cargo Freight Platform Lift for Industrial and Wearhouse.New Design IP65 100W LED Flood Light for Sports Lighting, 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 (Fr-218 BOPP Packing Tape Slitting Rewinding Machine). In the maximal PAC performance pH was found to be around the neutral (Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock;Farming Tractor Wheel Loader Tl2500 Cow Dairy Agricultural Tractor Loader Machinery). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Qr Code Watch Mobile Phone Case Deep Fiber Laser Marking Engraving Machine for Metal) which determines the coagulation performance (EVA Houseware Fridge Mat). 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 (Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Training Mat Floor/Inflatable Gymnastic Mat/Jumping Mat for Kids.
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