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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 (Portable Facial Skin Scrubber Scraper Machine for Beauty Care,www.wanyingtools.com). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality Dog Pet Toy Plastic Frisbee for Promotion;Smooth Surface Black HDPE Sheets for Wastewater Treatment;Tungsten Carbide Cold Heading Dies for Screws and Nuts). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Stainless Steel Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Carboxyl Methyl Cellulose Sodium),Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow. 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 (Scaffolding Board Cable Tray Panel Roll Forming Machine Line;24000L Chemical Corrosive Poisonous Liquid Tank Container with ISO Csc;Fiberglass Mesh/Fiberglass Mesh Cloth/Fiberglass Netting Mesh). However alum may result in high concentration of residual Al and is strongly affected by temperature (No Pollution Ce RoHS 30W Indoor UV Insect Killer Lamp Fly Mosquito Glue Trap Catcher) 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 (nbzkls.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System;Textile Mill Food Industry Garment Factory Oil Gas Steam Boiler;V4 Type Sintered Porous Filter with Female Thread;PVC Stripe Anti-Slip Door Mat with Color Logo;PVC Frontlit Flex Banner Exhibition Display Banner Flex (500dx500d 18X12 510g);1200*2200mm Black Powder Coated Dutch Barn Stall Door;Hot Sale Custom Ski Goggles Snowboard Goggles Straps Anti-Glare Ski Glasses Snow Goggles UV400).90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage(Hydraulic Scrap Metal Baling Machine for Metal;Black Bracelet Leather USB Drive Free Design Logo;Alcohol Antibacterial;SS304 Stainless Steel Tube Rectangular/Square Tube) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (The Lowest Price 27er/29er Carbon Fiber Mountain Bike Bicicleta), and it has been suggested as a lake restoration measure.
Coagulation-Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards(Hot Sale High Grade Popular Jacquard Curtain Fabric for Living Room/Bedroom) and also by water chemistry (pH and alkalinity) (New Product Ideas Wooden Musical Jewelry Storage Box). 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 (Wholesale Low Price Autumn Long Sleeve Women Lady Knitted Cardigan Sweater). At pH of 6.0-7.Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer(21/24/27 Speed/ Aluminum Alloy Carbon Frame Mens Bicycle Manufacturer Bikes for Adult,Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery). Algae also can affect coagulation due to characteristics such as morphology, motility,Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter(Large Music Controlled Colorful Laser Water Fountain,Anti-Corrosion Coated Line Pipe/Seamless Steel Pipe for Oil,Small Led Dimmer).
In the tropical semi-High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader-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.17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack. 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
CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,, 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(SKF NTN Chik Koyo Deep Groove Ball Bearings 6308 Zz Ball Bearing Turbo for Sale 40*90*23mm) and concentrations of total phosphorus (Upal Cheap Folding Steel Gazebo Tent with PVC Fabric Roof;Custom Manufacturer of Precision CNC Machined Graphite Electrodes) 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 (Top Supplier Lcoe Cost Down 1500V Dual Glass 320W 330W 340W Poly Solar Panel). 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). UV254Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700(DOM), mainly as humic substances (Hybrid Power System 150kw Electricity Generating System with Battery Bank).
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.)Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C, 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 toAluminum/SS304 Material Bathroom Mirror and Satin Shower Glass Sliding Door Handleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Knitted Pumpkin Hat).Water Play Equipment Inflatable Gym Air Track Mat-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 (Ae Bifacial Solar PV Panel 270W Poly German Quality). 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 UV254Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Long Rod Electrical Suspension High Voltage Polymer Insulator). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Carhartt Diaper Bagd).
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(Original Germany Bitzer Brand Compressor 4hc-1.2y). 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 Black-White Printed Product Operation Instruction). 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,Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes, 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 (Flexible PVC Steel Wire Reinfoced Spring Hose;55 65 75 86 98 Inch 3D LCD Touch Screen Smart Board TV All in One PC for Meeting Room & Classroom;Soft Touch 22 Inch Reborn Silicone Baby Doll Kits;Hidrotek Portable Suitcase Design Reverse Osmosis Demo Kits). However,Gear Operated Cast Iron Wafer Type Butterfly Valve.
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,Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair.Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835, 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 (New Design Silicon Watch Band Strap for Apple Watch Series 4 Mesh Shape Sport Band for Apple Watch). In the maximal PAC performance pH was found to be around the neutral (PU Imitation Clothing Leather Garments Material -Freman;Toner Cartridge Chip for Ricoh Aficio MP C3002 3502 (841735~841738 841647~841650)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean) which determines the coagulation performance (Auto Vertical Food Sachet Powder Pouch Filling Packaging Packing 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 (7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck).
Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall), charge and density, factors that influence directly in flock sedimentation.Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container(Slip on Blind Weld Neck Stainless Steel Flange Including Welding Neck Flange;Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale). 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 (Good Quality White and Brown Paper Soup Containers). Extracellular and surface-Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid(Shantui Relay D2660-02000 for Shantui Bulldozer,Sf606 Serve Motor Automatic Wood Cut off Saw Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Commercial Lighting Hotel Bar LED Track Lights).Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door(One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit), particularly humic susbtances. Humic substances are highly negatively charged (Red Blue LED Chips E27 Indoor Garden Cultivo Growing Lamp), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Stainless Steel Perforated Metal Grain Sieve). Maximal UV254removal was observed to be found around pH 6.0 (Women′s Mesh Contrast Pleat Fashion Black Tank Top). 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 (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer.
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