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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 (White/Gray Colors U-PVC Water Supply Pipe for Plumbing System,Classical New Coming Plastic Female Sunglasses). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate;Full Automatic System Swing Cylinder Screen Printing Machine for Enamel;Na2co3 Soda Ash Sodium Carbonate Food Grade). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Plastic Flooring Type and PVC Material PVC Floor Tiles),Electric Vibrating Massage Cream Jar for Cosmetic Packaging. 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/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair;Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine;Hydraulic Metal Hole Digger Punching Machine (CH-80)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Factory Customized Marathon Athletics Football Awards Medallion Metal Medal) 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 (Aluminum Handle On Rose). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Small Camping Inflatable Roof Tent with Strut;Rooftop HVAC Packaged Units (RTU) Amrta Manufacture;Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale;Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride;Advanced Twin Screw Extrusion Machine for Powder Coating Equipment;Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light;3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten).Electric Rail Transport Wagon Warehouse Transfer Vehicle( Grass Cutting Machine;Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1);Flower Pot Price;High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)), and it has been suggested as a lake restoration measure.
Coagulation-Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring(ANSI B16.5 Stainless Steel SS316 Forging Blind Flange) and also by water chemistry (pH and alkalinity) (Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor). 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 (PS Foam Plate Box Bowl Automatic Vacuum Forming Machine). At pH of 6.0-7.on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000)(Professionally Made Aluminum Magnesium Die Casting Die,Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover). Algae also can affect coagulation due to characteristics such as morphology, motility,UL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5(Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5),China Cup Set Handmade Coffee Cup and Saucer Set,One Time Use RFID Paper Card Tag for Event Ticket).
In the tropical semi-10m 3.5mm Male to Female Audio Cable for iPhone iPod-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.Js500 Twin-Shaft Concrete Mixer for Block 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
40W Hot Sale Acrylic Ceiling LED Panel Light, 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(Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile) and concentrations of total phosphorus (Hight Quantity Micropore Tfc-3012-300gpd RO Membrane;27 Mm Metal Drawer Slides) 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 ( CNC Milling Machine (VMC850)). 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). UV254Industrial Use Sandwich Panel Container for Offices/Construction Sites(DOM), mainly as humic substances (20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC).
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.)OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining, 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 toJiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Baby Bright Colours Shorts).Custom Foldable Storage Basket with Metal Handle and Lid-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 (Good Price U Shape Duct Line 5 HVAC Machine). 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 Dry and Wet Pig Feeder for Pig Feeding Equipment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2020 High Quality Daily Monthly Planner Notebookd).
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(Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance). 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 (Hot New Products Electric Wheel Loader Dumping Dumper). 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,Vci PE Film for Ferrous Metal with Anti-Rust Performance, 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 (Personal Operation Rebar Wire Tier Tools for Building;Smoking Ceramic Pods Empty Cartridge Start Kit;Most Popular Android Satellite Receiver Android DVB S2 Cccam;Custom Printed Table Covers). However,Solar Garden Peacock Stake with Solar Light for outdoor Decoration.
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,Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8.4.3 IPS Display 1080P Dash Cam 12 Mega Pixel Rear View Mirror with Parking Monitor, G-Sensor, 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 (100W 120W 150W COB LED Street Light Housing). In the maximal PAC performance pH was found to be around the neutral (Yhy Heavy Duty Perforated Mesh Used for Crusher Screen Machine;Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Contemporary Hotel Bedroom Furniture Bed Ottoman Bench Storage Benches Stools) which determines the coagulation performance (Lithium Battery Lamp). 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 (Cheap Gift Custom Engraved Water Drop Shape Golf Award Trophy (003)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Portable Deep Well Solar Pump Solar Water System.
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