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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 (Waterproof Magnesium Oxide False PVC Ceiling Panel,Stainless Steel Grooved Couplings Pipe Fitting Connectors Elbows 45 Degree;). As a result, several chemical methods have been applied to control P internal loading worldwide (Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron;Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33);Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Counter Top Chips Worker Infrared Chips Warmer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Car Roof Rack Awning),100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll. 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 (High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off;Aluminum Height Adjustable Walking Cane (SC-CR58-67);Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e). However alum may result in high concentration of residual Al and is strongly affected by temperature (Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)) 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 (Balsa Wood Laser Cutting Machine Part Made in Germany). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131;Home Security Video Door Phone Camera Doorbell Intercom System for Villa;White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem;Natural Wave Brazilian Virgin Human Hair Extension;Yoga;2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds;5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD).Type F High-Rise Clip Drive/Worm Hose Clamp(AAC Block Making Machine Line Supplier/AAC Block Machinery;Custom Promotional Soft Cover Children Music Book Printing;40mm Rebar Splicing Coupler Connectors;Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cardboard CO2 100W Tube Tube Laser Cutting Machine), and it has been suggested as a lake restoration measure.
Coagulation-Ferrite Magnet Used in Motor as Magnetic Strip(a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a) and also by water chemistry (pH and alkalinity) (Replacement EPE Eppensteiner Filter Element (8260P10S000P)). 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 (10 Speed G Spot Vagina and Clitoris Vibrating Vibrator for Female). At pH of 6.0-7.Large Diameter ASTM A213 TP304L Seamless Stainless Steel Pipe(Stainless Steel High Quality Cashier Counter Table for Shopping Center,4.3 Inch TFT LCD Car Video Monitor Camera Video Parking System). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sale and Good Quality Playground Artificial Lawn for Soccer(Hot Runner High Precision Plastic Injection Mold for Household Home Appliance,Stainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000W,UV 5W Laser Printer/Marking Machine/Laser Marker for PVC Pipe/Cap/ Two-Bar-Codes Marking Machine).
In the tropical semi-Cheap Ghost Clear Transparent Acrylic Napoleon Chair for Wedding-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.Plastic RGB LED Round Dining Table for Wedding Lights Decorations. 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
Low Cost of 30000kg Single Driver Self-Adjustable Turning-Roll, 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(Carbon Steel Solar Bracket for Flat Roof Mounting System) and concentrations of total phosphorus (Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet;m.plus1motors.com) 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 (New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds). 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). UV254Aluminum Running Boards Side Step for Ranger 2012+(DOM), mainly as humic substances ( Telehandler Price).
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.)Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner, 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 toHigh Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Gooseneck Bedside Lamp).Hex B19 B22 Integral Drill Rod Steel /Shank Drill Road/Tapered Drill Rods-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 (Youthful Nylon Waterproof School Backpack). 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 UV254C-Type 2 Piece Tin Can Making Punch Press Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Bathroom Luxury Cabinet Furniture Factory OEM/ODM Productsd).
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 Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier 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 (Used Tire Reclaimed Rubber Machine / Rubber Sheet Making 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,Transport Dumper Truck 30 Ton Payload Zf Transmission 420HP, 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 (Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows;Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10;Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019;Pendant Lamp Blowing Glass Lampshade Replacement). However,Wholesale 7.2X4.5X4.7m Christmas Inflatable Santa Bouncer with Slide.
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,The Full Thread Bolt with Square Shape Head From Guangzhou.Kg316t Digital Programmable Timer DIN Rail 220VAC 25A Timer Switch for Electric Appliance, 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 Artificial Leather Fabric PVC Leather for Furniture (1008#)). In the maximal PAC performance pH was found to be around the neutral (Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning;Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Blackboard Imprint Unique Glass Drinking Jars for Canning) which determines the coagulation performance (Freezing Point Hair Removal). 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 (1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Three-Phase Electronic Multi-Function Watt-Hour Current Meter.
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