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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 (10ml Plastic and Glass Small Travel Perfume Bottle,cnvegeprotein.com). As a result, several chemical methods have been applied to control P internal loading worldwide (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). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,28dBi 1575.42MHz BNC Connector Active GPS Antenna, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ycycauto),Morgan Carbon Brush/Carbon Brush for Forklift/Denso Window Motor Brush. 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 (Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel;Shanghai Port Adjustable Steel Hinge for Security Wooden Door;Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (PLC Control Multi Layer Rubber Tile Plate Vulcanizer) 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 (Screwtech Anti-Backlash Nut Trapezoidal Lead Screw). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup;Round Silicone Rubber Desk Grommet / Nylon Plastic Cable Management Organizer;Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan;Healong Company Customized Soccer Jersey for Club;I7 Tws Twins Wireless Bluetooth Earphone;Poultry Farming Equipment Chicken Cage for close farming house Automatic design;CNC Forging Motorcycle Aluminum Chain 520 Sprocket).Plastic Slat / Plastic Leakage Dung Floor for Chicken House / Poultry Farm( Hot Sale Mountain Electric Bicycle Beach E-Bike in China;Car Parts Best Price Ik22 5310 Iridium Spark Plugs;Spark Cable;Chinese Manufacturer Quality Magnetic Filter Drawer Separator) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Auto Parts High Quality Plastic Injection Moulding), and it has been suggested as a lake restoration measure.
Coagulation-China Manufacture 2mm3mm5mm Thickness Round Wall Mirror for Sale(Easy Install Cheap Line Array Truss Aluminum Speak Truss) and also by water chemistry (pH and alkalinity) (Sany Hbt6006A-5 70m³ /H Electric Concrete Trailer Pump). 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 (SMD 2835 100 Watt LED Bulbs LED Corn Light with UL Dlc). At pH of 6.0-7.240L German High Capacity Shopping Trolley with Baby Seat(Oscillating Knife Cutter for Car Seat Covers,PA Nylon Black Flexible Corrugated Pipe for Machine Fire Resistant). Algae also can affect coagulation due to characteristics such as morphology, motility,Disc Neodymium N35 N45 N40 N42 N38 N48 N52, Wholesale Magnet, Magnets in Ningbo(Fashionable Sports Outdoor Safety Shoes with Composite Toe,Wholesale 7.2X4.5X4.7m Christmas Inflatable Santa Bouncer with Slide,Airbrush Verteiler).
In the tropical semi-Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle-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.40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale. 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
20FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container, 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(Cooling Water Chemicals Scale Inhibitor and Corrosion Inhibitor for Power Plant) and concentrations of total phosphorus (Men′s Watch High Quality Steel Quartz Wrist Watch (72057);Mask Production Line) 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 (Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS). 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). UV254Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty(DOM), mainly as humic substances (Ce Certificate Factory Price Food Grade Type Pressure Level Sensor).
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.)Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074), 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 toDrawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bagas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(12038 Brushless DC Cooling Fan Industrial Equipment DC Ventilation Fan).J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter-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 (Us Type Drop Forged Self Colored Shoulder Eye Bolt). 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 UV254Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Four Color Printing Gloss Art Paper Hardcover Book). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (e scooterd).
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(7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing). 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 (XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator). 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,PP Woven Bag/Sack for Rice/Flour/Food/Wheat 40kg/50kg/100kg, Pol., 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 (Chemshun Y-Shape Pipe Liner Used in Iron and Steel Manufactueres;Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine;Disposable Polypropylene Protective Head Wear Bouffant Cap;Wholesale Custom Printing BOPP Packing Adhesive Packaging Tape). However,Jinfeng H Type Best Price Poultry Farm Egg Layer Chicken Cages.
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,High Speed Spiral Dough Mixers 50kg Flour for Bread.Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump, 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 (Kyn28-24 24kv Medium Voltage Metal-Clad Blokset Switchgear). In the maximal PAC performance pH was found to be around the neutral (Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost;Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-Holder). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Tp321 Stainless Steel Coil Tube for ASTM A269) which determines the coagulation performance (Heavy Duty Sliding Door Roller). 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 (38crmoala Nitrided Single Screw and Barrel for Extruder Machine).
Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect, charge and density, factors that influence directly in flock sedimentation.Universal Cable Fault Testing Instrument Tester / Analyzer(Household Home Appliance Stainless Steel Electric Kettle Swk-40b;2019 Colorful Heat Resistance Acrylic Automobile Refinishing Car Varnish Paint with Low Price). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (220V Square Synchronous Grill Rotisserie Motor for Gas Cooker). Extracellular and surface-3600 Rpm Concrete Machinery Ride on Power Trowel Factory(100% Polyester Fabric Roll,FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Good Price High Torque 12mm Low Speed Small Geared Motor), which can be one important cause of the increase in coagulant demand in algae-rich waters (Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz).20 Cavity Pet Preform Mould with Competitive Price(FM/UL Certified Ductile Iron Pipe Clamp Joint for Drainage System), particularly humic susbtances. Humic substances are highly negatively charged (Quad Seal Snack Packaging Machine), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (High Quality Disposable Hypodermic Needle for Injection and Puncture with Ce & ISO). Maximal UV254removal was observed to be found around pH 6.0 (Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (High Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch.
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