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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 (4 Seat Lead Battery Powered Electric Beach Buggy Cart (DN-4),Betaine Hcl). As a result, several chemical methods have been applied to control P internal loading worldwide (Hydraulic Cargo Freight Platform Lift for Industrial and Wearhouse;Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller;Dog Cat Car Products Travel Accessories Seat Pet Carrier Bag). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Cheap Price Creative Style Design of Men′s Leather Slippers, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Waterjet Spare Parts 050625-1 Pcv Maintenance Jit for Flow Hyplex Prime Pump),Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer. 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 (Y32f-112lm8 Small and Light PCB Relays with High Power for Comunication Equipment; Door Mat;Made in China Multi-Storey Steel Structure with Light Steel Frame). However alum may result in high concentration of residual Al and is strongly affected by temperature (Easy-to-Use School Office Invisible Stationery Tape) 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 (3.28 FT). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor;4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening);Cold Storage Warehouse Rack with Good Quality;Brc Welded Wire Mesh Fence/3D Curvy Welded Wire Mesh Fence;Design and Material;A4;High Efficiency Hook Type Shot Blasting Machine for Sale).Factory Direct Sell Spices Coffee Beans Grinding Machine/Herb Grinder Machine with Cyclone(Non-Toxic RTV Silicone Sealant of Full Automatic Machine;High Tensile Forged Chain with Conveyor for Conveying System;Heavy Duty Trommel Screener Used Forgravel in Quarry;M5 SMD with Internal Blind-Hole Thread with Pin (groove)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Interlocking Waterproof Removable Anti-Slip PVC Garage Floor Tile), and it has been suggested as a lake restoration measure.
Coagulation-China Metal Cooling Fan for Dry-Type Transformer(Best Quality Popular Lovely Washable Pet Accessories Luxury Soft Dog Bed) and also by water chemistry (pH and alkalinity) (Customized Wire Mesh for Decorative Garden Fence). 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 (Kitchen Equipment Fan Cooling 5 Layers Cooler Refrigerator Cake Showcase Display). At pH of 6.0-7.Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine(Fan Cooling Oval Design Commercial Cake Display Showcase Fridge,China Qingdao Factory Interlocking PVC Garage Floor). Algae also can affect coagulation due to characteristics such as morphology, motility,430 Black Mirror Decorative Stainless Steel Sheet in Foshan(Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm,Double Arm Medical Pendant for Anesthesia (HFP-DS240/380),18mm Thickness Laminated Switchable Smart Dimming Office Glass).
In the tropical semi-Jingsun High Efficiency 380W 400W Perc Mono Solar Panel-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.Make Your Own Design Blank Fitness Tights with Laser Hole. 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
RFID and Remote Controller Small Electronic Lock with Password, 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(Ce Eco-Friendly 24V Electric Motor Operated SS304 Water Flow Control Valve for Drinking) and concentrations of total phosphorus (Incoloy 825 Pipe for Industry Application;Cheap Corrugated Sheet Raw Material Color Coate Steel Coil) 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 (Hook Vintage Weathered White Wall-Mounted Wood Coat Rack with Chalkboard Labels). 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). UV254M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports(DOM), mainly as humic substances (250ml Empty Refillable Pet Material Plastic Shampoo Bottle).
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.)HRC60 4 Flutes Corner Radius Solid Carbide Cutting Tools End Mill, 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 to120 Grit Sand Blasting Media/Sandblasting Abrasives/Almandite/Garnet Sand 80 for Waterjet Cuttingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Max Elongation 750% Stretching Resistance Rubber Tubing for Industrial Hose).M5 SMD with Internal Blind-Hole Thread with Pin (groove)-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 (Virtual Reality Egg Game Machine Amusement Riding Machine for Sale). 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 Storey Worker Living Block Container House Supplier%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ad-P720 Hot-Selling Perfume Glass Bottle 100ml). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Blank Chip Card Manufacturers Cheap Priced).
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(Hidrotek Water Filter Cartridge with Sediment Carbon). 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 (9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting). 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,Ethylene-Propylene-Diene Monomer Rubber Waterproof Materials, 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 (Automatic Plastic Pet Preform Injection Moulding Machine Price;High Quality Polyurethane Adhesive for Scrap Sponge;Carbon Steel Carry Idler Belt Conveyor Guide Roller;Hydraulic Guillotine Shearing Machine (zys-13*4000) with CE and ISO9001 Certification). However,New Arrival Household Self-Washed Flat Mops Cleaning.
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,New Type Portable 380V Electric Winch in Stock.10ml Portable Spray Perfume Glass Empty Bottle Atomizer, 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 (Rexroth Hydraulic Pump A8V55/80/107 Replacement Spare Parts). In the maximal PAC performance pH was found to be around the neutral (Factory Supply Customized Sintered Inner Gear Rotor by Iron Alloy Powder;2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire) which determines the coagulation performance (Multi-Function Instant Nutrition Baby Food Powder Making Machine). 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 (High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling).
Ce Approved Acrylic Mini LED Letters Sign for Outdoor, charge and density, factors that influence directly in flock sedimentation.Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner(ASTM A792 PPGI PPGL Roof Sheet Cold Rolled Steel Coil;Modular Functional L Shape Living Room Leather Sofa). 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 (Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone). Extracellular and surface-Best Quality Hydroponic Film Greenhouse Steel Structure Construction(Cell Culture Dishes,High Quality CNC Turning Center Parts Machinery Auto Parts). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Factory Price Gerneral Usage Silicone Sealant), which can be one important cause of the increase in coagulant demand in algae-rich waters (Transparent 240W SMD 3030 Outdoor LED Flood Lamp).Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line(ISO Factory of Disc Cutter for Tunnel Boring Machine), particularly humic susbtances. Humic substances are highly negatively charged (Pharmaceutical Intermediate Peptide Oxytocin 50-56-6 Oxytocin Acetate), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut). Maximal UV254removal was observed to be found around pH 6.0 (Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966). 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 (Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1).
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