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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 (Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair,Cnc Brass Lathe Turning Part Screw). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Diesel Fuel Leak off Pipe for Mercedes-Benz). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Asphalt Pavement Bitumen Road Crack Seal Equipment, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Best Workman Steel Toe Boots Work Shoes Safety Shoes),Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss. 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 (Automatic Plastic Pet Preform Injection Moulding Machine Price;High Quality Polyurethane Adhesive for Scrap Sponge;Carbon Steel Carry Idler Belt Conveyor Guide Roller). However alum may result in high concentration of residual Al and is strongly affected by temperature (Rexroth Hydraulic Pump A8V55/80/107 Replacement Spare Parts) 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 (Hydroponic Plant Lamp Full Spectrum 1000W LED Grow Light for Indoor Plants). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Factory Supply Customized Sintered Inner Gear Rotor by Iron Alloy Powder;2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card;Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire;High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling;Natural Gemstone Green Tiger Eye Stone Beads Strand 16 Wholesale Loose Beads;ASTM A792 PPGI PPGL Roof Sheet Cold Rolled Steel Coil;Modular Functional L Shape Living Room Leather Sofa).3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer(Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone;High Quality CNC Turning Center Parts Machinery Auto Parts;Powerway Lean Pipe Joint Rack System Fluency Strip;Factory Price Gerneral Usage Silicone Sealant) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Transparent 240W SMD 3030 Outdoor LED Flood Lamp), and it has been suggested as a lake restoration measure.
Coagulation-2019 Bdu Army Camouflage Uniform with 3-Color Desert Color(ISO Factory of Disc Cutter for Tunnel Boring Machine) and also by water chemistry (pH and alkalinity) (CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut). 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 (Decorative Mesh Panels). At pH of 6.0-7.Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery(Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966,Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture). Algae also can affect coagulation due to characteristics such as morphology, motility,High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock(Dac34640037 Wheel Bearing /Automotive Bearing/ Hub Bearing,Aluminum CNC Al5052 / Al6061 / Al6063 Machining Turning Parts for Mil-Spec Electronics,300 Bar Ginza).
In the tropical semi-Stable Steel Flat Glass Transport Rack with Safe Support Protection-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.Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine. 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
Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym, 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 Henan Factory Manufacturer Industrial Wood Chipper Wood Chipper Shredder) and concentrations of total phosphorus (Banbury Rotors 3L Lab Plastic and Rubber Mixer Machine;Professional Industrial Weighing Scale 500kg) 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 (Ce Approved Gobal Warranty 200kVA 100kVA 50kVA 25kVA Diesel Generator Price). 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). UV25435.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck(DOM), mainly as humic substances (Aluminum/Aluminium Foil/Coil for Retort Pouch/Bag/Stand-up Pouch A8079/1235/8011-Soft 5.9/6 Microns).
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.)Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe, 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 toWholesale Dining Room Furniture White Plastic Folding Tables and Chairsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Spring Bolt Wholesaler Quotes & PriceList).Fertilizer Binder and Dispersant Sodium Lignin Sulfonate-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 (CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts). 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 UV254Reducer Hydraulic Fitting with Swivel Nut (2D)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (19′′ Smart Table Android Windows PC Touch Screen Kiosk). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Double Spindle Drilling and Tapping Machine Tools for Machining Metal Pipesd).
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(Hot Selling Construction Machine 50cbm/H Ready Mixed Concrete Mixing Plant). 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 (Metal Enclosure Withdrawable Distribution Switchgear Cabinet Low Voltage). 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,Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable, 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 Price 1100 Aluminum Disc Discs Circle Round Plate;Bsg-901 High Quality Cheap Price Soccer Goal Nets;Galvanized Steel Concrete Nail Use for Construction;CNC Machined Stainless Steel Fittings Pipe Flange). However,Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming 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,UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1.Bright Polished Galvanzied Common Iron Wire Nails, 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 (Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing). In the maximal PAC performance pH was found to be around the neutral (Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel;Shanghai Port Adjustable Steel Hinge for Security Wooden Door). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price) which determines the coagulation performance (Veneer Dryer Machine for Face Veneer Core Drying 2019). 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 (PLC Control Multi Layer Rubber Tile Plate Vulcanizer).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.How a Gravity Belt Thickener Works Thickening or Dewatering.
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