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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 (Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz,China Supplier 330ml Custom Glass Amber/Blue/Clear Empty Bottle for Beer). As a result, several chemical methods have been applied to control P internal loading worldwide (FM/UL Certified Ductile Iron Pipe Clamp Joint for Drainage System;High Quality Disposable Hypodermic Needle for Injection and Puncture with Ce & ISO;Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Diaper Bag Backpack Baby),OEM Aluminum Housing Fuel Filter Housing for Truck/Train Parts. 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 (L Sealing Automatic Egg Tray Heat Shrink Wrapping Packaging Machine;Industrial RO Water Purification-1500gpd with Black Cabinet (0.25T/H);Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed) 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 (Bestguarder Digital Night Vision Monocular with 700m Detectin Range IP66 Waterproof). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (600L Stainless Steel Beer Fermentation Tank 3-Vessels Brewhouse;Slim LED Lightbar Automotive LED Lights Bar for Offroad Vehicles;High Quality 50W/100W/150W/200W IP65 LED Flood Work Light for Garden;Bitzer Compressor 6f-40.2 Valve Plate with 82mm Piston;Alpha Gpc Sleep;3 Fold Telescopic Ball Bearing Drawer Slide Rail;L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906)).Rare Earth Metal Material Cerium Target for Magnetron Sputtering System(Intelligent Roll Printing Machine for PP Woven Sack Printer;Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative;Prepainted Cold Rolled Steel Coil for Building Materials;530ml Glass Drinking Water Bottle with Silicone Sleeve&Handle Lid) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cotton Garden Work Glove with Single Side PVC Dots), and it has been suggested as a lake restoration measure.
Coagulation-Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom(Filter Press Small-Size Metal Plate Hydraulic Press Machine) and also by water chemistry (pH and alkalinity) (Double Rows PCD Segments 7 Inch PCD Cup Wheel for Concrete). 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 (Women Bodysuit). At pH of 6.0-7.Custom Diecasting Fashion Zinc Alloy Enamel Metal Name Tag(EU Standard Top Quality Portable Indoor Playground Equipment,Best Brush Customized Synthetic Flat Foundation Makeup Brush Professional Cosmetics Accessory). Algae also can affect coagulation due to characteristics such as morphology, motility,Semi-Automatic LCD IC PCB Cof Soldering Machine(Black Cohosh Extract Triterpene (Cimicifuga racemosa extract),Chubont Hot Selling Waterproof Duffel Trolley Bag Size 19/22 Inch,Portable Led Work Light).
In the tropical semi-Socket Weld Stainless Steel Flange Ss 150#, Pipe Flanges Schedule 40-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.Household Home Textile Cleaning Cloth Warp Knitted Absorbency Cheap Kitchen Wash Clean. 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
Plastic Reflective Raised Pavement Marker Road Stud, 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(China Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating) and concentrations of total phosphorus (Logo Branded Hi-Spec Heavy Duty Tool Box Set with Parts Organiser Tray;function refractory brick) 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 (Industrial Fine Bubble Membrane Disc Air Diffusers for Waste Water). 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). UV254Most Infinix Like Mobile Phones 6.26′′ HD+19: 0, IPS 720*1520 Display Android 9.0(DOM), mainly as humic substances (Best Readymade Contemporary Grey Tiny Compact Modern Ensuite Small Shower Room Price).
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.)Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer, 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 toFactory Polyester Solid Color Single /Double Faced Satin Ribbonfor Wedding Chirstmasas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Laser Marking System).Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover-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 (Scaffolding Deck Galvanized Steel Walking Board Metal Plank for Scaffold 250*40*1.2*4000mm). 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 UV254Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ce ISO Approved Yiwu Medical Factory Price Plastic Disposable Blood Lancet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Taillight Ledd).
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(China Supply MTP/APC Female to FC/APC Fanout Cable 12 Fibers Single Mode Patch Cord). 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 (15mm Thickness Industrial NdFeB Rare Earth Magnet). 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,Waterproof Travel Portable Makeup Bag Wash Gargle Bag, 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 (Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique;Desktop Fiber Laser Marking Machine with Computer Price $3300;Compatible Quality Handy Color Jumbo Stretch Cling Film;Hot Cold Mini Fridge). However,Car Repair Equipment Underground Garage Lift with Double Scissor Lifts.
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,Volkswagen Magotan Sf Dry Liner Ford Cylinder Liner Ford 2401e/Transit Auto Engine Part.High Temperature Multi-Jet Ultrasonic Heat Measure Meter, 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 (China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (Solar Power Refrigerator 12V DC Mini Fridge;19 Inch Wall Mounted Indoor Wireless Advertising LCD Screen). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Contec Cms-Vesd Digital Multi-Functional Visual Stethoscope with SpO2/Estetoscopio) which determines the coagulation performance (Purified Air Powered Respirator). 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 (Asphalt Pavement Bitumen Road Crack Seal Equipment).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Automatic Canned Aloe Vera Cube Dicing Cutting Cutter Machine.
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