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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 (30cm Round Clear Plastic Pot Plant Trolley,Plastic Waste Bin). As a result, several chemical methods have been applied to control P internal loading worldwide (Saint Glory-Washable White Color Down Alternative Comforter for Hotel (Home);Original Monitor Display Panel for Cat320d Excavator;China Manufacrure Mobile Asphalt Batch Mix Plant for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Sdlg B877f Backhoe Loader Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,JIS G3441 Machining and Structure Alloy Steel Pipe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Xide Indoor Vvvf Escalator with 30 Degree 1000mm Step Width),250sv-Sp Mining Centrifugal Vertical Wet Slurry Pit Pumps. 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 (Anti-Corrosion 1.5mm FRP Roofing Skylight Fiberglass Sheets;High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts;60 Grit Mini Abrasive Flap Disc for Carbon Steels). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Speed Skateboard SKF 608 Hand Spinner Fidget Toy Bearing with Zz RS Seals) 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 (Pvc Insulated Copper Cable Suppliers for Sale). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Stone Plastic Composite Spc Rvp Flooring Floor Mat Making Machine;Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525;Micro Water Tank Level Transducer for Wall Hung Gas Boiler;High Temperature Alternative Stainless Steel Band in Different Package;Conical Dual Screw Mixer;Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp;Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner).Micropile Tube as Umbrella for Tunnel Portal Od73mm Wt6mm, Steel Pipe(New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges;Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit;Gea Flat Kaori Heat Exchanger Copper Small PTFE Heat Exchanger Tube Water;Hf Vacuum Dryer Machine with Advanced High Frequency Technology) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine), and it has been suggested as a lake restoration measure.
Coagulation-Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill(700mm RP HP UHP High Quality Graphite Electrode) and also by water chemistry (pH and alkalinity) (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch). 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 (Vandal Proof No Keypad Telephone for Railway Metro). At pH of 6.0-7.Portable Marking Equipment System Laser Wire Marking Machine Price(Furniture Laminate Sheet/HPL Panel/Building Material,7). Algae also can affect coagulation due to characteristics such as morphology, motility,3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten, Kitchen Utensils, Dutch Oven(Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale,Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant,blockmachinechina).
In the tropical semi-200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter-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.Log Debarker, Peeling Head, Log Peeling Head, Heavy Duty Log Peeling Head, Wood Peeling Lathe. 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
Thermal Transfer Waterproof Tearproof Matt Silver Pet Label, 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(New Mini Loader Radlader Mini Zl936 Wheel Loader) and concentrations of total phosphorus (High Quality Compair Air Compressor Air Filter 50273;Clear Gusseted Bags) 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 (Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop). 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). UV254SMD P4 Outdoor Full Color Rental HD LED Display(DOM), mainly as humic substances (Multi-Layer HDPE PE PPR Pipe Production Line).
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.)Toroidal Inductor Coils Tlc/1A-221m-00 for Speaker Use., Radio etc Use., 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 Top Quality BPA Free Biodegradable Bamboo Toothbrushas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(APP Remote Control WiFi Smart Plug /Socket Work with Amazon Alexa & Google Home).Smooth Surface Black HDPE Sheets for Wastewater Treatment-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 (Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting). 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 UV254Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4 Color Cardboard Flexo Printer Slotter Machined).
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(Private Label Hip Circle Mini Fitness Resistance Elastic Latex Bands). 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 (2 Ton Brand New Small Cheap Backhoe Loader for Sale). 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,High Precision Injection Molding Plastic Parts in China (STK-PL-1055), 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 (Factory Manufacturer CNC Dual Use Combined Metal Sheet Plate & Tube Pipe Fiber Laser Cutter;3.0V 4mm Diameter Coreless Mini Strong Vibration Motor with Bracket;Combustibility Analyzer Flame Testing Equipment for Building Material ISO 11925;Api Butterfly Valve). However,Fan Cooling Oval Design Commercial Cake Display Showcase Fridge.
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,Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable.CNC Machine Linear Guide Accordion Bellows Cover, 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 (35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck). In the maximal PAC performance pH was found to be around the neutral (China Factory Supply 25mm Blackout Pleated Honeycomb Blinds;China Manufacturers Round Welded Stainless Seamless Steel Pipes 316). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring) which determines the coagulation performance (Led Surgical Headlight). 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 (4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic.
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