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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 (Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube,GPS Satellite Lock GPS Seal Lock Tracker for Container Tracking and Cargo Security Solution). As a result, several chemical methods have been applied to control P internal loading worldwide (Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles;Aluminium Profile Wood Color Tilt and Turn Casement Windows and Stainless Screen Doors;Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Arrival Household Self-Washed Flat Mops Cleaning). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fashionable Sports Outdoor Safety Shoes with Composite Toe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Filling and Sealing Machine Sausage Type Automatic Silicone Sealant Filling Machine),China Manufacturer Aluminium Oxide Abrasive Metal Grinding Polish Cutting Disc Wheel for Grinder. 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 (Chinese Furniture Outdoor Garden Furniture Aluminum Sofa Sets;Sino Heavy Duty Truck HOWO Parts Lowest Price Rear Shock Absorber with Wg1642440021 From manca;Breathable Pet Dog Shoes with Reflective Magic Tape Straps). However alum may result in high concentration of residual Al and is strongly affected by temperature (2018 Newest 12inch Music Sound Box for Computer) 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 (New Fashion Elegant Fashion Face Ladies Wrist Watch Stainless Steel Bracelet Watch (71189)). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Cutting Tool Solid Carbide Tool Taps (TS-100002);Cyclone Mesh Turbo Diamond Saw Blade for Ceramic Tile;16800mAh 800A Car Emergency Battery Booster Portable Jump Starter;Best Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable;Low Price with Logo Empty Cylinder Plastic Jar for Whey Protein Powder;Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle;High Quality Antibiotics Powder Enrofloxacin CAS 93106-60-6).Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets(Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller;RFID and Remote Controller Small Electronic Lock with Password;Customized Rechargeable Solar LiFePO4 48V 100ah Lithium Energy Storage Battery with BMS;OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Biodegradable Packaging Small Plastic Compartment Storage Box for Food), and it has been suggested as a lake restoration measure.
Coagulation-Hip-Hop Streetwear Custom Brand Fashion Man Hoodie(Industrial Horizontal Double Ribbon Blender Mixer Machine for Dry Powder Mixing) and also by water chemistry (pH and alkalinity) (Electrically Heat Furnace Prime Quality Radiant Tubes). 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 (Tungsten Cemented Carbide Abrasive Water Jet Nozzles). At pH of 6.0-7.Boiler Seamless Steel Tube En10216-216mo3, Steel Pressure Tube Pipe 25crmo4(Australian Standard Thermal Break Residential Aluminium Wooden Glass Sliding Window,Colored Corrugated Steel Roofing Sheet with ISO9001). Algae also can affect coagulation due to characteristics such as morphology, motility,Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine(Temperature and Humidity Controller with 5 to 95%Rh (XMT-9007-8),Porcelain Tea Cup and Saucer Sets Wholesale Tableware Ceramic,99.95% High Quality Tungsten Tubes Wall Thickness 1mm).
In the tropical semi-Rgt-16-Ye Ruler Baby Scale 16kg, Mechanical Infant Scale-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.Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom. 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
Wholesale Men′s Leather Waterproof Outdoor Trekking Boots, 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(Large Sand PE Film Cover Vegetable Growing Tunnel Greenhouse) and concentrations of total phosphorus (OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated;Rotor Core Loss Induction Motor) 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 (2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter). 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). UV25410kw 20kw 30kw 50kw Small Gas Generator for Home Use(DOM), mainly as humic substances (Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825)).
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.)Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush, 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 toElectronic Smoke Digitizer Quartz Atomizer Short Quartz Tubeas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Stainless Steel Phillips Countersunk Flat Head Self Drilling Concrete Screw).P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen-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 (Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress). 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 UV254Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Professional Fabrication Metal Sheet Mechanical Stamping Machine 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 (Outdoor Cooler 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(Waterproof Straight Male Female Sensor Connector). 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 (Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush). 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,Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale, 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 (Custom Hardware Lathe Turning Steel Metal Parts High Precision CNC Machinery/Machined/Machining;Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy;PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material;Pvc Zigzag Mat). However,Handles Operated Cast Iron EPDM Seat Wafer 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,DC Colorful Battery Operated Small Hand Fan for Outdoor Use.Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill, Solid Top, for Sewer, Stormwater, 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 (Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle). In the maximal PAC performance pH was found to be around the neutral (White Chemical Coating Powder for Fast Dry Sublimation Paper;Trenchless Directional Tricone Drill HDD Reamer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (AISI 304 316L 309S 317L 321 904L 421 Stainless Steel Strip) which determines the coagulation performance (www.shunstone.com). 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 (Nyp Rotor Type Oil Pump High Viscosity Internal Gear).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized High Performance Industrial Oil Hydraulic Cylinder for Metallurgical Industry.
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