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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 ( Splicing Machine S6,Calendar Boxes). As a result, several chemical methods have been applied to control P internal loading worldwide (Double Deck High Quality Aluminum Pontoon Boat for Sale;Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885);Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Floor Mounted Glass U Clamp Channel for Glass Balustrade). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High-Precision Aluminium Casting Aluminum Die Casting Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (35mm 45mm 55mm Mild Round Seamless JIS G3445 Stkm 15A Stkm12c Steel Pipe),Best Price Split Air Conditioner Stand/AC Stand. 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 (High Quality Curve Spear Tunnel Bolt for Concrete Ring;Brand New Forklift with Double Front pneumatic Tire;Automatic Small Round Bottle Water Washing Filling Capping Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration) 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 (1000w Laser Cutting Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor;Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods;White/Gray Colors U-PVC Water Supply Pipe for Plumbing System;Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate;Carbon Steel Sleeve Anchor Bolt with Hex Nut and Washer Screw Type Expansion;Full Automatic System Swing Cylinder Screen Printing Machine for Enamel;Na2co3 Soda Ash Sodium Carbonate Food Grade).Fiberglass FRP Sandwich Panel for Insulation Truck Body Construction(Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag;High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair;Supply Tungsten Carbide and Stamping Dies;Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hydraulic Metal Hole Digger Punching Machine (CH-80)), and it has been suggested as a lake restoration measure.
Coagulation-Custom Sequin Patch for Clothing Handbag Backpack(Factory Customized Marathon Athletics Football Awards Medallion Metal Medal) and also by water chemistry (pH and alkalinity) (Small Camping Inflatable Roof Tent with Strut). 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 (Machine Professional Heavy Duty Tile Cutter for DIY Market). At pH of 6.0-7.Weight Loss Equipment with Cryolipolsis Fat Freezing 40K Cavitation Rflipo Laser(Rooftop HVAC Packaged Units (RTU) Amrta Manufacture,Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising(Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride,Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light,www.hengyaomachinery.com).
In the tropical semi-Tisco High Quality Cold/Hot Rolled Stainless Welded Steel Pipe Grade 201-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.Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding. 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
Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner, 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(Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)) and concentrations of total phosphorus (High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price;Beacon Company Factory OEM/ODM Product) 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 (Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor). 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). UV2547 Liters Vertical Type Commercial Butchery Manual Sausage Filler(DOM), mainly as humic substances (Professionally Made Aluminum Magnesium Die Casting Die).
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.)E-Bay Hot Sales Silicone Baby Dolls for Kids Toys, 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 toNEMA IP65 Wall Mount Electric Metal Cabinetsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Wholesale Square Pump Spray Clear Perfume Jar/Container Glass Bottle).AAC Block Making Machine Line Supplier/AAC Block Machinery-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 (Hight Quantity Micropore Tfc-3012-300gpd RO Membrane). 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 UV254Desktop Fiber Laser Marking Machine with Computer Price $3300%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Environmental Heat Pumpd).
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( CNC Milling Machine (VMC850)). 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 (20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC). 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,Eco Recycled Kraft Paper Box for Salad and Lunch, 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 (860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag;Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor;Samsung 46 49 55 LCD video wall Samsung LCD screen;Before Sewing Machine Series Round Knife Cutting Machine Bb65). However,Heavy Duty Galvanized Stacking Steel Pallet Shelving with Posts.
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,Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz.Custom Design Stainless Steel Sheet Metal Fabrication Box 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 (China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price). In the maximal PAC performance pH was found to be around the neutral (Good Price U Shape Duct Line 5 HVAC Machine;Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes) which determines the coagulation performance (Aluminum Door). 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 (Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Tubular Polyethylene Plastic Film Blowing Machine.
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