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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 (Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring,10′′wheel). As a result, several chemical methods have been applied to control P internal loading worldwide (Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench;Fashion Double Striped Non-Slip Entrance Mat). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Book Matched Marble Tiles Wall Design in Hotel Hall Natural Blue Macubas Marble Slab, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Narrow Bezel Video Wall),Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain. 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 (DC Colorful Battery Operated Small Hand Fan for Outdoor Use;1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve;TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use). However alum may result in high concentration of residual Al and is strongly affected by temperature (Wholesale Comfortable Men′s Winter Leather Snow Boots) 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 (Brick Block Mould). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Promotion Cheap Woven Wristbands Event RFID Woven Wristband;Non Woven Wheel for Stainless Steel Polishing and Grinding;High Quality Free Sample Woven Label for Garment Accessories;Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing;Stainless Steel 304 316 Camlock Coupling Male F Type Adapter Male Thread Quick Coupling;Shenzhen Customized Metal Stamping Parts Fabrication Service;Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)).Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display(Precision Aluminium 6061 CNC Machining Parts for Baffle Bulkhead Flow Valve (F-155);Micron Circular Stainless Steel Filter Disc;UV Coated MDF Sheet (Solid Color;PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China New Technology Swimming Pool Heat Pump (MDY50D)), and it has been suggested as a lake restoration measure.
Coagulation-Industrial Coal Fired 8 MW Hot Water Boiler Factory Price(Agriculture Machinery Belt Banded Cogged V-Belt) and also by water chemistry (pH and alkalinity) (Nonwoven PP Fabric Nonwoven Needle Punched Geotextile). 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 (Brass Alloy Open Type Floor Socket Junction Boxes). At pH of 6.0-7.Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer(12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape,Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case). Algae also can affect coagulation due to characteristics such as morphology, motility,27.5′′ Lithium Battery Mountain Style Electric Bike(Anti-Aging Dredger UHMWPE/HDPE Sand Mud Oil Dredge Floater Pipe Pipeline,600g Synthetic Fiber Ceiling Filter/Roof Filter/ Roll Filter for Spray Painting Booth,Automatic Pipe Socketing Machine).
In the tropical semi-Marine Salvage and Refloatation Rubber Airbag Roller Bags-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.Girls Unicorn Costume Party Dress Tutu Kids Cute Flower Princess Pageant Carnival Clothes. 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
Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates, 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(4.0cbm Automatic Feeding Mixer Concrete Batch Truck with Rotation Drum) and concentrations of total phosphorus (Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw;m.aeonlaser.net) 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 (Best Price Split Air Conditioner Stand/AC Stand). 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). UV254Stainless Steel Mesh Screen Automatic Self-Cleaning Filter(DOM), mainly as humic substances (Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser).
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.)China Supply High Quality MIFARE® DESFire® EV1 2K/4K/8K RFID White PVC Card, 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 toJq350 Small Electric Vertical Pan Cement Blender Concrete Mixeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plating Solution Filtration).AISI ASTM 409 410 420 430 440 Cold Rolled Stainless Steel Coil-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 (Siboasi Best Selling Badminton Shuttlecock Feeder Machine). 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 UV254Semi-Automatic Hydraulic Leather Football Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Artificial Turf Seriesd).
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(Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)). 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 (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine). 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,Decorative Polyester Board Rocplex, Polyester Plywood, 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-Class Sld-6121 Paper Sticker High Speed Slitting Machine;Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer;Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory;Corrugated Panel). However,Car Air Compressor Tire Inflator Pressure Gauge.
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,Hot Selling Polyresin Garden Dark Blue Birdhouse for Tree Decoration.Dac34640037 Wheel Bearing /Automotive Bearing/ Hub Bearing, 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 (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)). In the maximal PAC performance pH was found to be around the neutral (China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China;Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (LG936 LG938 Front End Loader Parts Gas Spring 29330011391) which determines the coagulation performance (Diamond Desk Set). 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 (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump).
Galvanized Steel Sheet Metal Roofing Price/Gi Corrugated Steel Sheet/Zinc Roofing Sheet, charge and density, factors that influence directly in flock sedimentation.Good Quality Free Sample Bauxite Price Per Ton(360ml Glassware/Glass Bottle/Honey Jar/Jar for Bird′s Nest;Plastic Casement Window). 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 Mechanical Grade B 3240 Epoxy Insulation Fiberglass Sheet). Extracellular and surface-Intelligent Auto Tracking Indoor Mini Camera Smart Life Tuya IP Camera(Disposable Coveralls Bulk,Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Recoil Steel Hot Coiled Extension Coil Compression Heavy Duty Spring), which can be one important cause of the increase in coagulant demand in algae-rich waters ( IPS 720*1520 Display Android 9.0).Modular Concrete Batching Plant by Twin Shaft Mixer 3000/2000(Auto Car Parts Good Quality 16620-0s010 Tensioner Pulley), particularly humic susbtances. Humic substances are highly negatively charged (Computerized Jacquard Lace Braiding Machinery), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Women′s Stretchy Yoga Training Mesh Leggings with Side Pocket). Maximal UV254removal was observed to be found around pH 6.0 (Wholesale Promotional Children Painting Apron). 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 (Poultry Farming Automatic Chicken Feeding Pan System).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesaler HRC60 Carbide Corner Radius End Mills Chamferied Cutter.
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