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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 (Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt,Customized Metal Blank Promotion Gift Key Finder). As a result, several chemical methods have been applied to control P internal loading worldwide (2.0mm Pitch Pin Header SMT Type R Sereis Single Row Dual Housing;Steel Structure Welding Steel Structure Metal Building;High Temperature Fireproof PU Coated Silica Fabric). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Polypropylene Strapping Band Production Line/PP Strap Making Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (OEM Small Parts Processing CNC Aluminium Machining CNC Milling Machining),Ce Approved Disposable Blood Bag for Ozone Blood Therapy. 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 (3 Way Manual Staple Gun with Staples for Hand Tools;Golf Practice Nets and Cage/Professional Training Golf Net;Automatic Plastic and Glass Bottle Inductor Sealing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Surgical Instrument LED Shadowless Operation Lamp) 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 (White Fireproof Pvc Panel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Stray Inductance 210~2100uh Frame Core Current-Compensated Common Mode Choke Coils;Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift;Precision Oscillating Multitool Sharp Cutting Blade for Wood;Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047);Cabina de espray de la pintura de los muebles de China;1300*700*700mm Vertical CNC Milling Machine CNC Lathe CNC Machine Center CNC Machine Tool;20L Semi Automatic China Bottle Pet Blower).Molten Steel Ladle for Casting, Steel Ladle Manufacture(professional Manufacturer One Arm Motorized Multifunction for Medical Products;Banana Slicer Cutter Perfect for Fruit Salad Yellow Banana Cutting;New High Quality 3D Brick Pattern PVC Wall Paper for Home Decoration;Electric Baking Heat Preservation Deck Oven Manufacture) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Electric Vibrating Massage Cream Jar for Cosmetic Packaging), and it has been suggested as a lake restoration measure.
Coagulation-2kw Solar Hybrid System with Solar Controller MPPT(Gym Fitness Equipment EPDM Surface Gym Rubber Flooring Mat/Rubber Flooring with 500*5000/1000*1000mm) and also by water chemistry (pH and alkalinity) (High Precision Injection Molding Plastic Parts in China (STK-PL-1055)). 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 (Relay 40a). At pH of 6.0-7.400W Vertical Axis Windmill Generator (200W-5kw)(Venlo Polycarbonate Covering Material Greenhouse on Sale,Rubber Recycling Machine Powder Tire Derived Fuel Machine Small Tyre Recycling Plants). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes(Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling,VGA multi screen video wall LCD video wall panel with wall screen matrix,2019 Bolted Type Cement Silo with Filter /Types of Silos).
In the tropical semi-100%Cotton Woven Jacquard Brand Design Beach Towel-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.100kw Electric Power Plant or Biogas Gas Engine Generator Price. 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
China Wholesale Hydraulic Industrial Winch for Mining Well, 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(Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75) and concentrations of total phosphorus (Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting;Cup Wire Wheels Brush Set & Reduced Wire Breakage and Longer Life) 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 (ASTM A242 A588 Corten Steel Plate/Sheet/Coil/ Corten a/B/ SPA-H / B480). 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). UV254Black Shelf Table Storage Basket Rack Kitchen Wire Mesh Cabinet Organiser(DOM), mainly as humic substances (3.5mm).
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.)Transmission Parts Linear Ball Bearing with Shaft for Setting Machine, 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 toDental Emax Empress Crown From China Dental Labas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Best Price Commercial Lighting All in One Integrated Solar Street Light).School Exercise Book Making Machine 2.3.4 Colors-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 (XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet). 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 UV254Dn630mm Plastic Pipe Butt Fusion Welding Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Lower Price Luxury Waterproof Spc Vinyl Floor Tile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Popular Design Double Bridge Women Metal Sunglassesd).
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(High Tensile Strength Stainless Steel Wire From Factory). 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 (Galvanized Material Metal Workshop and Warehouse Peb Light Steel Structure). 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,2019 Hot Sale Air Cooling Laser Wafer Dicing Equipment, 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 (PP Grid Composite Safety Protection Netting for Construction Building;Solar Panel Mounting Solutions Mounting Bracket Mounting Kit Mounting System;800kgs Steel Wire Rope Hand Winch for Lifting;Ac External Rotor Motor). However,Smart Access Control RFID NFC Epoxy Crystal Tag Card.
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,Fashion Leather Wristband USB Disk 4GB to 32GB.Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt, 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 (10m3 Mobile LPG Filling Skid Station for Gas Cylinders). In the maximal PAC performance pH was found to be around the neutral (Woodworking Machine One Head Economic Model CNC Router;Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope) which determines the coagulation performance (Hot Sale Hydraulic Marine Equipment Winch for Sale). 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 (Hanna Good Quality Door Spray Paint Machine).
Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring, charge and density, factors that influence directly in flock sedimentation.Chemical Vacuum Coating Single Stage Rotary Piston Pumps(Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger;Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes). 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 (2018 Small Machine Room Gearless Traction Xide Passenger Elevator). Extracellular and surface-Air Compressor Parts Normally Closed Type 24V Solenoid Valve(Seatbelts Automatic Cutting and Winding Machine,All Dielectric Aramid Yarn Armor Double Jacket Aerial ADSS Fiber Optic Cable). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Flanged Bolted Bonnet Cast Steel Swing Check Valve Supplier), which can be one important cause of the increase in coagulant demand in algae-rich waters (Supply Carton Sealing Use and Rubber Adhesive Duct Tape).Laminated Curtain Wall Glass with Colored PVB Film(Customized Steel Wire Small Conveyor Belt System), particularly humic susbtances. Humic substances are highly negatively charged (Aluminum Composite Panel Aluminium Honeycomb Backed Stone Panel), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Good Quality Cheap Bluetooth Music Zero Gravity Shiatsu Massage Chair). Maximal UV254removal was observed to be found around pH 6.0 (Metallzied Polyester Film 9um MPET Film for Capacitor Use). 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 (Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21).
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