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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 (Rubber Raw Material Kneader Machine -75L Banbury Mixer,Stanley Hydraulic Power Unit). As a result, several chemical methods have been applied to control P internal loading worldwide (Cheap China 2 Inch Wafer Stainless Steel Butterfly Valve;The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture;DIN7504 Stainless Steel Self Drilling Drywall Screw). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Construction Pipes Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pet Soft TPR Dog Toy High Quality Pet Toy From China Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Height Adjustable Hospital Under Arm Crutch for Walking Aid),Manufacturer Woven Patches and Customized Woven Badge. 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 (Synthetic Filament Spunbonded and Needlepunched Nonwoven Geotextiles;DIY Modern Metal Wine Bottle Rack Organizer;Circular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1). However alum may result in high concentration of residual Al and is strongly affected by temperature (3-Wheel Motorcycle with 1500W Motor and EEC Certificate) 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 (Eva Foam Toys For Children). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom;Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor;Patient Modular Monitor with Wireless Network and Wire Network;25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake;Exciter Stator Winding;Medical Infusion Pump for Human and Veterinary with Fluid Warmer;Ce Certificated Acm-60 PTFE Powder Grinding Mill).Portable for Mobile 120W 24V Automatic Car Key Cutting Machine(Buildings Materials ASA PVC Roof Tile Roofing Sheet;Cigar Tobacco Foil Ziplock Bags Custom Blunt Wraps for Medical Cannabis Packaging;Extreme Heat Resistant Gloves;Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Auto Crane Electrical Overhead Cable with Steel Wire), and it has been suggested as a lake restoration measure.
Coagulation-Fashionable New Products Twin Screw Extruder for Pet Recycling(Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801) and also by water chemistry (pH and alkalinity) (Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer). 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 (4605A483 Car Parts Brake Caliper Repair Seal Kit for Mitsubishi Pajero Year 2007-2010). At pH of 6.0-7.V4 Type Sintered Porous Filter with Female Thread(Reflecting Aluminum Film Vacuum Evaporation Coating Equipment,5mm Wall Mounted Hotel LED Lighted Bathroom Mirror). Algae also can affect coagulation due to characteristics such as morphology, motility,Full Automatic Silicon Sealant Sausage Film Filling and Sealing Machine(Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings,China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal,High Quality Wallpaper Smoother).
In the tropical semi-Steel Drilling Water Well Filter / Bridge Slot Screen Pipe-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.Commerical Vehicle Accessories for Trailer Camper Van Caravan Safety Rearview Camera System. 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
Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer, 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(Foil Induction Sealing Machine for Glass Plastic Bottle Jar) and concentrations of total phosphorus (Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials;White Fiberglass Gridding Cloth) 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 (England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification). 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). UV254Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange(DOM), mainly as humic substances (Lash Camellia Ellipse Flat Eyelash Extension Makeup Tool Lashes Extensions 102).
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.)Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set, 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 toJaws End Us Type Drop Forged Turnbuckle Riggingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Customized Automotive Latching Relay and Shunt Assemblies for Energy Meters).Good Quality Mixing Tank Vacuum Mixing Pot Mixing Reactor Vessel-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 (Eco Friendly Biodegradable Soup Bowl Food Container). 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 UV2542 in 1 Mini Qi Fast Pad for Apple Watch 1 2 3 4 Series Airpods Wireless Charger%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Coronavirus Igg/Igm Diagnostic Testd).
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(Heat Insulation and Fireproof Composite Sandwich Wall Panel). 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 (Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan). 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,SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66, 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 (Standard Sizes Aluminium Galvanized Mild Steel U Channel;Hot Sale Men Injection Casual Shoes Sport Running Sneaker Shoes 9319;High Elastic Nylon Breathable Arm Elbow Sleeve for Sports;Natural Colorant Coloring Agent 10: 1 Ginger Extract Powder). However,Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil.
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,7.5HP Centrifugal Circulation Swimming Pool Water Pump.for Bahrain Market Hot Cafe Vending Machine F303V, 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 (Silicone Hand Pipe Hand Tobacco Pipes Smoking Pipe with Glass Bowl). In the maximal PAC performance pH was found to be around the neutral (AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars;Hot Sale Low Price Small IGBT Magnetic Induction 40kg Steel Scrap Melting Furnace for Metal Melting). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (28dBi 1575.42MHz BNC Connector Active GPS Antenna) which determines the coagulation performance (Casting Impeller). 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 (Electric Vehicle Brushless DC Motor 3kw 1500rpm 48V).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality HVAC Exhaust or Supply Plastic Air Valve.
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