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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 ( Fabric,Chrome Steel Piston Rod for Hydraulic Cylinder). As a result, several chemical methods have been applied to control P internal loading worldwide (3m 467MP Strong Adhesive Double Sided Transfer Tape;Fertilizing Machine Farm Tractor Mounted CDR-1000 Fertilizer Spreader;Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Biodegradable Resealable Plastic Food Packaging with Zipper). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Agriculture Cultivator Springs Double Spring Tines 3.5-12mm, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (peas-pa),Magic Mirror Facial Skin Analyzer / 3D Face Camera. 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 (Corrugated Aluminum Composite Panel for Suspended False Ceiling Decoration;Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt;Laboratory 2 Roll Mixing Mills Rubber Open Mixer Machine Factory). However alum may result in high concentration of residual Al and is strongly affected by temperature (Professional Neck Jacquard Woven Lanyard Strap) 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 (12bar 440L/Min Oilless Air Compressor with Air Tank). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Foton/Forland 4X2 Mobile Snack/BBQ/Coffee/Hot Food Truck; Pullover Fleece Tie Dye Hoody;Customized Machine Dustproof Bellow Cover for The CNC Guide;Stainless Steel Pneumatic Three Way Non-Retention Sanitary Ball Valve;New Design Custom Metal Round Shaped Engraved Gold Plated Dog Identity Tag Necklace with Rope;Stainless Steel for Indoor Wall Construction Materials;Photo Album Self Adhesive PVC Foam Sheets for Inner Pages).Original OTG Mobile Phone Micro-USB to USB-C Gender Adapter for Samsung S10(ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037;Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine;Furniture Hardware Pulls;Single Prong Metal Chrome Pegboard Bracket Merchandising Display Hook) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal), and it has been suggested as a lake restoration measure.
Coagulation-Copper Antique Beverage Party Tub Ice Bucket Wine Cooler(Gear Box Forged Steel Bw Ends Full Welded Ball Valve) and also by water chemistry (pH and alkalinity) (Organic Waste Gas Treatment Device Gas Disposal on Hot Sale). 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 (Dettol Kn95 Air Protect Mask). At pH of 6.0-7.Good Price PVC Ceiling Panel / PVC Ceiling Sheet and PVC Wall Panel(Floor Glass Fiber Sandwich Honeycomb Panel for Truck Body Door Shower Room,OEM Trailer Parts Drop Axle Forging Spindle). Algae also can affect coagulation due to characteristics such as morphology, motility,OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication(10ml Portable Spray Perfume Glass Empty Bottle Atomizer,Wine Glass Label Gold Foil Wine Adhesive Private Label Bottle Metal Red Wine Label,One-Stop Solution Nanofiltration NF Reverse Osmosis RO Membrane Manufacturing System).
In the tropical semi-Easy-to-Use School Office Invisible Stationery Tape-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.High Sensitivity Metal Detector for Security Inspection. 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
Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies, 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(2019 New Bio Vacuum Cavitation RF 6 in 1 Fat Freezing Body Slimming Salon SPA Machine) and concentrations of total phosphorus (Desktop Digital Servo Control Universal Material Tensile Testing Machine 8201s;Sublimation National Flag) 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 (3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer). 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). UV2542018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds(DOM), mainly as humic substances ( LED Mounter).
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.)Steel Structure Roofs System TPO Waterproof Membranes, 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 toBathroom Shower Concealed Square Anti-Odor Ideal 304 Stainless Steel Floor Drainas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Strong Corrosion Resistance Polyester Long Fiber Needle Punched Nonwoven Geotextile).20000L Injection Blow Molding Machine Used Extrusion Blow Molding Machine-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 (Silicone Invisible Strapless Bras Reusable Backless Bras for Women (RS 015)). 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 UV254Automatic Abrasive DIY Sandblaster for Motorcycle Outer Assy Surface Processing%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (LED Lighted Mirror with Bluetooth Functions). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Baby Bedroom Lampd).
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(Supermarket for Cold Room Price Air Cooled Condenser Unit). 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 (Plastic Fork Mould for Cake Disposable Tableware Injection Molding). 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,Yhy Heavy Duty Perforated Mesh Used for Crusher Screen Machine, 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 (HR/CR/GI High Frequency Longitudinal Seam Tube Mill;Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4);Small Scaled Laboratory Pharmaceutical Dry Mixing Machine;2018 New Men′s Slim Sport Wear Basketball Suit Men Sport Jogger Pants for Running). However,Customized Ring Die for 560/508/420/350 Pellet Machine.
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,Hot Sale Glass Manual Salt Grinder Pepper Mills/Spice Jars.Custom Polyester Woven Patch Logo Snapback Hats, 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 (Outdoor High Pressure Isolating Vacuum Load Switch). In the maximal PAC performance pH was found to be around the neutral (Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale;Full Car Key for Chrysler 5+1 Button Remote Control). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Black Amplifier Aluminum Instrument Enclosure Boxes for Electronic Projects) which determines the coagulation performance (Metal Pipe Fabric Laser Cutting Machine for Brass/Copper Sheet). 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 (ASTM A193 B7 5/8inch 100mm C/W Fluorocarbon Coated Green Stud Bolt).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile.
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