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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 (High Quality Double Link Ra DVI D 24+1 Pin Connector,Guote Brand Gct/F Series Permanent Magnet Drum and Roller Magnetic Separator). As a result, several chemical methods have been applied to control P internal loading worldwide (Electrical Insulation Flexible Crepe Paper Tube for Transformer;High Quality Humidity Control Chamber Artificial Climate Chamber;Best Quality Hydroponic Film Greenhouse Steel Structure Construction). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Stainless Steel Wire Rope Zoo Mesh Aviary Mesh for Animal Enclosure). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Drx Plastic Injection Mould Making Professional Tech Mold Maker, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (750w Ac Servo Motor Driver),Car Accessories Wholesale 60 Cm Semi-Metal Car Wiper Blade Used for Toyota 85212-42110. 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 (Potable Expansion Vessel Suitable for Sanitary Water Applications;IP65 Waterproof Exterior Hanging Batten Linear Lighting LED Tri-Proof Light;Transformer-Base Factory Equipment UPS 3 Three Phase in 3 Phase Output 60-400 kVA Online UPS). However alum may result in high concentration of residual Al and is strongly affected by temperature (Forged Custom Exterior French Door Wrought Iron Double Entry Doors) 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 (Aux Adapter Socket 3.5mm Jack Dashboard Mount Extension Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (92 16: 9 Motorized Projection Screens with Black Casing;China Supplier Customized Pressing Stamping Parts; 4 Butanediol Bdo CAS 110-63-4 with Lowest Price;Marine Studless Link Anchor Chain for Sales;High Quality Pot;Woma Acrylic Shower Panel Cubicle Room for Old People (Y698);15t/H Hot Selling Professional Factory Price Palm Nut Crusher Machine with Ce).White Chemical Coating Powder for Fast Dry Sublimation Paper(Rugged Construction Material for Steel Screens for Platforms and Floor Channels.;Htzh-2h Portable Sf6 6-in-1 Gas Comprehensive Analyzer;Single use Sanitary Disposable nonwoven Bus/Speed train/Hotel/Airline/bus/car/train HeadRest Cover;Cemented Carbide Round Rods) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Shenzhen Customized Fr4 FPC Flexible Circuit Board Customized PCB Manufacturing PCB), and it has been suggested as a lake restoration measure.
Coagulation-Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price(Difference Between PPGI and PPGL of Price and Type) and also by water chemistry (pH and alkalinity) ( Dumper Truck). 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 (Bullet Flood Fixture). At pH of 6.0-7.Hot Dipped Galvanized Steel Horse / Sheep Wire, Cheap Cattle / Field Fencing( ISO9001,Hot Dipped Galvanized 358 High Security Fence/ Anti Climb Fence). Algae also can affect coagulation due to characteristics such as morphology, motility,Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System(Shenzhen Manufactory Specilized in LED Light Manufacturing Line Setup,Floating Oil Seal 150-27-00020 Excavator Parts,Pickup Stick Jumbo).
In the tropical semi-HS20-600 Shipping Lifting Device Customized Hydraulic Station-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.Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer. 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
Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold, 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(Best Price China 1325 CNC Plasma Cutting Machine) and concentrations of total phosphorus (Pneumatic Rubber Wheel for Wheelbarrow 4.10/3.50-4;ODM OEM 25kg 50kg Grain Sugar Flour Rice Feed Seed Fertilizer Laminated PP Woven Bag) 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 (Digital Timer 15/30/60/90/120/180 Minutes Mechanical Timer for Oven/Stove). 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). UV254Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA(DOM), mainly as humic substances (Trunking System Busbar Bus Duct 2000A Bus Way).
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.)Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide, 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 toUL Approved Rubber Covered Hose/BS6391 Type 3 Rubber Covered Hose/1.5/2.5as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(0.12~1.5mm Tk PPGI Steel Coil From Shandong Factory for Building).Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper-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 (Galvanized Jaw and Jaw Type Closed Body Rigging Screw Turnbuckle). 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 UV254Amino Acids L-Citrulline, L-Ornithine, L-Valine, L-Lysine, L-Arginine, L-Histidine, L-Cysteine Salts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Cryotherapy Fat Removal Coolsculpting System Body Contouring 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 (FDAd).
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(Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates). 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 (Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display). 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,Atex Approved Level Measuring Instrument Level Sensor, 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 (4 Inch Cast Iron Wafer Pneumatic Butterfly Valve;Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror;Electrical Insulator Fibreglass Separator for Lead Acid Battery;16 Oz Glass Jars). However,3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline.
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 Outdoor Patio Rattan Hotel Furniture.Rope and Net PP Filament Yarn Extruding Machine, 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 (Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice). In the maximal PAC performance pH was found to be around the neutral (Environmentally Diesel Powder Coating Bake Curing Oven;Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Indoor or Outdoor Power Distribution Equipment Metal Box) which determines the coagulation performance (915 Type Steel Metal Corrugated Q235 Galvanized Floor Decking Sheet). 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 (100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer).
PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel, charge and density, factors that influence directly in flock sedimentation.Agricultural Rotary Disc Mower, Grass Cutting Machine(The Best One Doors Commercial Glass Display Showcase Drink Coolers Upright Fridge for Sale;Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern). 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 (Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer). Extracellular and surface-Dk7725b New Condition Wire EDM Electrical Discharge Machine(12 Volt DC Motor Fan 30X30X10 Hot Sale Electric 12V Fan,Industrial Chemicals HPMC Products). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Stainless Steel Grating for Chemical Plant Platform), which can be one important cause of the increase in coagulant demand in algae-rich waters ( Granite Outdoor Table).Porcelain Custom Logo Ceramic Tiki Cup Mug(Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233), particularly humic susbtances. Humic substances are highly negatively charged (BNC DC RCA DVR Cable CCTV Camera Video Audio Power Cable for Surveillance Camera), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Sc Single Mode Single Fiber 100m Mini Fiber Media Converter). Maximal UV254removal was observed to be found around pH 6.0 (Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area). 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 (Cylinder Actuated Cement Powder Butterfly Valve).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Biometric Fingerprint and RFID Card Access Control Reader Sf1.
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