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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 (10 Supply Water Pipe Insulation HDPE Outer Pipe,Low Standard Pressure Gauge with Black Steel Case Bezel Bottom Coonction). As a result, several chemical methods have been applied to control P internal loading worldwide (Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet;Reducer Hydraulic Fitting with Swivel Nut (2D);High Manganese Mn13cr2 Mn18cr2 Jaw Plate Crusher Parts). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Colorful Commercial PVC Vinyl Flooring for Office). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Plastic Cover Aluminum A60 7W E27 LED Global Bulb, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Acrylic Adhesive Tape),PU Imitation Clothing Leather Garments Material -Freman. 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 (Auto Air Poppet Valves Cover Plastic Mould / Mold;African Trapezoidal Triangular Pulley Roller for Sliding Gate Door-Silvery;High Sensitivity Metal Detector for Security Inspection). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Power/Torque Density 7.5kw 2500rpm AC Servo 3 Phase Motor) 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 (tunnelcutter). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10W Auto Oval Work Car Light Blue Red LED Forklift Warning Head Lamps;Prefab Multifunctional Steel Structureg for Wholesales Construction Material; Paper Bags;A2 Fireproof Inorganic Mineral Material for A2 ACP Panel ACP Sheet;High Quality Semi Automatic Plastic Jar Blow Moulding Machine;304 Stainless Steel Pipe Manufacture in China;Hospital Equipment 23L Benchtop Autoclave).Furniture Okoume Veneer Pine Birch Poplar Core Commercial Plywood(Light Controller DMX Controller for Stage Light;Alluvial Sand Tin Mining Process Equipment Rollers Electrostatic Separator;Rubber Compound Mixing Machine/Open Mixing Mill with Stock Blender;Movely Lovable Panda Household Soft Plush Antiskid Indoor Home Slippers) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Fasion Style Custom Indian Embroidery Patch), and it has been suggested as a lake restoration measure.
Coagulation-Factory Bulk Self-Indicating Blue Silica Gel with High Adsorption(Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor) and also by water chemistry (pH and alkalinity) (Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt). 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 (Good Quality Gold Stretched Brass Golden Faucet). At pH of 6.0-7.3mm/0.4mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration(Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C,Plastic Reflective Raised Pavement Marker Road Stud). Algae also can affect coagulation due to characteristics such as morphology, motility,Double Sided Heat Tape for Electrical Adhesive Masking Packing Tape(Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style,PU Foam Plastic Squishy Slow Rising Toy for Unicorn,Water & Liquids Filtration Blasting Abrasive 80 Mesh Garnet Sand with ISO 9001 Standard).
In the tropical semi-PE PP LDPE LLDPE Agriculture Film Recycling Machine-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.DIN6915 Ss 316 304 Stainless Steel High Tensile Hexagon Nut with Bolt for Structural Bolting. 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
SD16L Super Wetland Dozer 120kw Shantui Swamp Bull Dozer Price Bulldozer, 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(Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava) and concentrations of total phosphorus (Public Address System High Power Range Outdoor Column Speaker;API Flange End Stainless Steel Floating Ball Valve) 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 (Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace). 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). UV254Double Arm Medical Pendant for Anesthesia (HFP-DS240/380)(DOM), mainly as humic substances (98% Polypeptide Hormones CAS 113-79-1 Argpressin Acetate as Neurotransmitter).
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.)Disposable Take out Paper Food Salad Sushi Lunch Box Container, 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 toSelf Tapping Screw Roofing Screw Bimetal Screwas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Duplicate Car Key Maker).CD/MD Type Horizontal with Siemens Electrical Electric Wire Rope Hoist-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 (2 Head Embroidery Machine Cap Flat T Shirt Embroidery). 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 UV254Newest Hot Sales Metal 360 Degree Reading Glasses with Case%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (627 2rsd).
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(Silicon Baby Bib Super Waterproof with Food Slot). 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 (99.999% Sio2 Quartz Grain Sand 100-200 Mesh for Quartz Rod). 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,Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock, 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 (High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle;304 Stainless Steel Deep Drawn Parts for Kitchen Equipment;9oz 16oz 17oz Stainless Steel Water Bottle BPA Free Metal Water Bottle for Promotion;Carbon Steel Pressure Tank). However,Carbide 4 Flutes HRC60 Blue Coated Milling Cutters.
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,120W Foldable Mono Crystalline Solar Panel PV Module Battery Power System Amazon OEM.Safety Disposable Shoe Cover for Lab Visitor, 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 (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo). In the maximal PAC performance pH was found to be around the neutral (Optical Fiber Cable MTP/MPO Cassette for Data Center;High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720) which determines the coagulation performance (Hedge trimmer). 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 (Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve).
Aluminum Hard Equipment Gift Flight Case for Guitar, charge and density, factors that influence directly in flock sedimentation.High Quality Wooden Cabinet Design Shoe Display Unit for Shop(High quality 110V DC Power Supply for American Market;Best Polystyrene Sandwich Board Manufacturer). 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 (High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping). Extracellular and surface-Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine(Sun Barrier Black Netting Mesh Shade Shade 40% UV,Customized Microfiber Sport Towel for Swimming Towel). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Customized Small Module Sintered Metal Product Spur Gear Pinion), which can be one important cause of the increase in coagulant demand in algae-rich waters (Wg9130583017 Sino Truck Spare Parts Combination Switch).High Speed Disposable Lunch Box Egg Tray Making Forming Machine(Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag), particularly humic susbtances. Humic substances are highly negatively charged (Best Brand Keyless Entry Door Lock Hotel Door Lock System), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Waterproof Magnesium Oxide False PVC Ceiling Panel). Maximal UV254removal was observed to be found around pH 6.0 (Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron). 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 (Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door.
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