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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 (Extrusion Mould Cemented Tungsten Carbide Wire Drawing Die,Bestguarder Digital Night Vision Monocular with 700m Detectin Range IP66 Waterproof). As a result, several chemical methods have been applied to control P internal loading worldwide (New Material of Coated and Veneered Wooden Grain Paper;Automatic Food Coating Chocolate Spraying Dk Air Atomizing Nozzle;High Glossy/Matt/Embossed/UV/Natural Wood Veneer Faced Melamine Laminated Colored MDF for Furniture). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,China Food Fruit Vegetables Spiral Quick Freezer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Alpha Gpc Sleep),FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia. 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 (Best Quality Square Mini Takoyaki Grill Pan with Helper Handle;Simple Shool Teaching Portable Monocular Microscope for Medical Products;Hydraulic Metal Chips Block Moulding Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hip-Hop Streetwear Custom Brand Fashion Man Hoodie) 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 (Prepainted Cold Rolled Steel Coil for Building Materials). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (20000L Injection Blow Molding Machine Used Extrusion Blow Molding Machine;Biodegradable Sugarcane Bagasse Pulp Takeaway Fast Food Packaging;Hot Sale Jumbo Roll Double Sided Adhesive Tissue Tape for Cars (DTS10G-15);3p 4p Electrical Dual Power 1250A Transfer Switch;Women Bodysuit;High Density Multi-Layer PCB Prototype PCB Printed Circuit Board Professional Manufacturer;Hair Growth Ingredient Biotinoyl Tripeptide-1 CAS 299157-54-3).SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker(Professional Palm Handheld Veterinary Ultrasound Diagnostic System;Queene/MID Drive Fat Tire Ebike with LCD Display for Performance Riding MTB;Portable Led Work Light;Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Selling Polyresin Garden Dark Blue Birdhouse for Tree Decoration), and it has been suggested as a lake restoration measure.
Coagulation-Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75(Marine Salvage and Refloatation Rubber Airbag Roller Bags) and also by water chemistry (pH and alkalinity) ( DC Brushless Fan Light PCBA). 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 (function refractory brick). At pH of 6.0-7.New Version Breakage-Proof Multihead Weigher for Biscuits(Food Packaging Laminated Roll Film for Food Packaging,Aluminum Composite Panel Details with Color Quantity MOQ). Algae also can affect coagulation due to characteristics such as morphology, motility,Log Debarker Veneer Rotary Peeling Machine(High Quality Virgin PMMA 3mm Clear Cast Acrylic Sheet Price,Panic/Emergency Button/Switch for Alarm System (PB68),China SS304/316/316L Stainless Steel Water Cartridge Membrane Filter Housing).
In the tropical semi-IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor-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.DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval. 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
Portable Solar Lantern with Built-in Solar Panel, 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(Dedi 55′′ Floor Standing Advertising Outdoor Digital Signage LCD Totems) and concentrations of total phosphorus (Rcm Certification for Scanning Electronic Input Pen;Laser Marking System) 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 (30ml Cosmetic Packaging Electroplating Essence Press Dropper Glass Bottle). 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). UV254Asphalt Pavement Bitumen Road Crack Seal Equipment(DOM), mainly as humic substances (Germany Imported IPL Xenon Flash Lamp/IPL Lamp/Xenon Lamp).
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.)Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss, 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 to3D Finish Soundproof Movable Partition Wall for Meeting Roomas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Foton Forland 4X2 Type 24V or 12V Mobile Billboard Truck LED Display).3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer-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 (Non-Smoke E7018 E6018 Welding Rod Carbon Steel Welding Electrodes). 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 UV2542019 Bdu Army Camouflage Uniform with 3-Color Desert Color%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Lovol Rice Combine Harvester-Small Tank with Two Hoppers). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hot Cold Mini Fridged).
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(Top Quality 40m3/H Small Mobile Mini Twin-Shaft Mixer with Pump). 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 (Permanent Magnetic Separator for Conveyor Belts). 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,Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery, 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 (Customized Stainless Steel Cut Wire Shots Sand Blasting Grit;Custmoized High- Quality Decoration Mirror Stainless Steel Curtain Wall;Transmission Line Steel Monopole Steel Tower;3 Stage Telescopic Hydraulic Cylinder). However,High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock.
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,Stable Steel Flat Glass Transport Rack with Safe Support Protection.Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine, 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 ( Camera). In the maximal PAC performance pH was found to be around the neutral (Industrial Air Cooled Heat Pump Water Chiller in Many Field;14kw Heating Capacity Evi Air to Water Heat Pump). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (1HP Floting Wheel Aerator) which determines the coagulation performance (OEM Forging Steel Straight Jaw Locking Plier). 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 (48mm Strong Tensile Strength Brown BOPP Adhesive Box Packing Tape for Carton Sealing).
Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym, charge and density, factors that influence directly in flock sedimentation.35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck(Kylie New Arrival Lipstick+Lips Pencil Makeup Waterproof Lip Gloss Lipstick Set;Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board). 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 (P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen). Extracellular and surface-Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe(Empty Liquid Lipstick Containers,Automatic High Speed Welding Manipulator Machine). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Stainless Steel Juice Multi-Bag Filter Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card).Fertilizer Binder and Dispersant Sodium Lignin Sulfonate(2000bph Chicken Slaughtering Equipment Line), particularly humic susbtances. Humic substances are highly negatively charged (China Manufactory Manufacturer Injection Molded Plastic Bucket Mold), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment). Maximal UV254removal was observed to be found around pH 6.0 (Portable Far Infrared Sauna Dome with Tourmaline Stone). 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 (30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Reducer Hydraulic Fitting with Swivel Nut (2D).
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