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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 (Factory Price Rotary 1530 4 Axis CNC Router for Promotion,Hot Selling Cooking Pot). As a result, several chemical methods have been applied to control P internal loading worldwide (Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag;61539 Double Handle 4 Inch South American Style Faucet;3 Axle 50-80t Cimc Low Bed Trailer Lowboy Semi Trailer Trcuk Tractor Trailer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Us Type Drop Forged Self Colored Shoulder Eye Bolt). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Industrial Water Hose),Thin Wall 7049 7050 Aluminum Tube with PVC Package. 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 (Four Color Printing Gloss Art Paper Hardcover Book;Environmental Luminescent White Light Glow in The Dark Powder Pigment;7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing). However alum may result in high concentration of residual Al and is strongly affected by temperature (XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator) 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 (10pin Pin Header). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Electric Convection Bread Bakery Oven Made in China;Biogas Digester Double Membrane Gas Holder Anaerobic Fermentation Tank;Chemshun Y-Shape Pipe Liner Used in Iron and Steel Manufactueres;Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine;New Style Ultrasonic Pipe Compressor Cleaning Machine;Disposable Polypropylene Protective Head Wear Bouffant Cap;Kyn28-24 24kv Medium Voltage Metal-Clad Blokset Switchgear).Impa651710 Marine Wholesale Seawater Thermometer(Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost;Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-Holder;Cheap Trampolines For Sale;Tp321 Stainless Steel Coil Tube for ASTM A269) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (38crmoala Nitrided Single Screw and Barrel for Extruder Machine), and it has been suggested as a lake restoration measure.
Coagulation-Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)(Household Home Appliance Stainless Steel Electric Kettle Swk-40b) and also by water chemistry (pH and alkalinity) (2019 Colorful Heat Resistance Acrylic Automobile Refinishing Car Varnish Paint with Low Price). 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 (www.miracle-leather-bag.com). At pH of 6.0-7.Breathable Pet Dog Shoes with Reflective Magic Tape Straps(220V Square Synchronous Grill Rotisserie Motor for Gas Cooker,FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food). Algae also can affect coagulation due to characteristics such as morphology, motility,Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker(Good Price High Torque 12mm Low Speed Small Geared Motor,Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz,Electric 80r New Design 24V DC Gear Motor with Od 63mm (SLT-63ZYT)).
In the tropical semi-Best Price 1325 Woodworking CNC Router Machine Equipment-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.8FT Wood Log Debarker Machine for Plywood Machinery. 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
OEM Hardware Factory Custom Fabrication CNC Aluminum Signet, 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(Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA) and concentrations of total phosphorus (High Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12;100kVA/80kw Cummins Emergency Use/Marine/Water Cooling/Electric Starting/Boat Generator) 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 (Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer). 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). UV254on-off Automotive Switches Automotive Rocker Switch 16A Rocker Switch(DOM), mainly as humic substances (Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed).
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.)Youthful Nylon Waterproof School Backpack, 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 toBitzer Compressor 6f-40.2 Valve Plate with 82mm Pistonas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Qtj4-20 Hydraulic Concrete Cement Compressed Block Making Machine in Africa Market).Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag-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 (Intelligent Roll Printing Machine for PP Woven Sack Printer). 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 UV2542018 Newest Camping Hiking Bug Net Hammock%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2019 Hot Sale 190t Polyester Mummy Sleeping Bag for Camping Hiking Picnicd).
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(Cotton Garden Work Glove with Single Side PVC Dots). 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 (Filter Press Small-Size Metal Plate Hydraulic Press Machine). 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,Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making 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 (Best Brush Customized Synthetic Flat Foundation Makeup Brush Professional Cosmetics Accessory;Black Cohosh Extract Triterpene (Cimicifuga racemosa extract);Chubont Hot Selling Waterproof Duffel Trolley Bag Size 19/22 Inch;Chocolate Chip Cookie Making Machine). However,Glass Shower Door Frame Waterproof Seal PVC Seal.
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,Cheap Spring Bonnell Inner Spring for Bedroom Mattress.Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer, 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 (Household Multi-Function 16.8V Double Speed Lithium Cordless Electric Drill). In the maximal PAC performance pH was found to be around the neutral (Fast Food Catering Airstream Trailers or Mobile Electric Airstream Food Truck Food Caravan Cart;China Desktop Zirconia Dental Porcelain Sintering Furnace 1700c Four-Sided Heating). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Logo Branded Hi-Spec Heavy Duty Tool Box Set with Parts Organiser Tray) which determines the coagulation performance (Sublimation Mug With Spoon). 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 (VOD 1550nm Direct Modulated Optical Transmitter RF Input Local Program).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.DC 12V 24V Mini Portable Camping Car Freezer for Car.
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