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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 (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo,High Quality Kaeser Air Compressor Oil Separator Element 6.2012.1). As a result, several chemical methods have been applied to control P internal loading worldwide (Optical Fiber Cable MTP/MPO Cassette for Data Center;High Tensile Wire Rope Lifting Jaw Jaw Turnbuckle Rigging;Touch Screen Digitizer LCD Display Assembly for Samsung Galaxy J720). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Low Temperature Extended Stem Cryogenic Forged Steel Gate Valve). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Oscillating Knife Cutter for Car Seat Covers, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Exaggerated Crystal Leal Earrings),Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP). 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 110V DC Power Supply for American Market;Best Polystyrene Sandwich Board Manufacturer;High Demand Precision Machining CNC Parts CNC Rapid Aluminum Prototyping). However alum may result in high concentration of residual Al and is strongly affected by temperature (Customized Microfiber Sport Towel for Swimming Towel) 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 (Velvet Eye Mask). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Customized Small Module Sintered Metal Product Spur Gear Pinion;Wg9130583017 Sino Truck Spare Parts Combination Switch;Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag;Waterproof Magnesium Oxide False PVC Ceiling Panel;Touch Screen Lcd;Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron;Hottest 2 in 1 Using Stick and Handy Vacuum Cleaner (WSD1302-33)).6061 6063 Extrude Aluminum Extrusion Profile Section Supplier(Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261;Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data;China Industrial 6 Axis Multifunctional Universal Robot Arm Kit for Cellphone Production;High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Aluminum Height Adjustable Walking Cane (SC-CR58-67)), and it has been suggested as a lake restoration measure.
Coagulation-Excellent Quality Wooden Cosmetic Display Counter for Retail Store(Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e) and also by water chemistry (pH and alkalinity) (Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)). 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 (Professional Factory LED Light Touch Sensor Switch 3-6mm Thick Vanity Smart Mirror Glass Wholesale). At pH of 6.0-7.Small Silent Biogas Electric Generator for Biogas Plant(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). Algae also can affect coagulation due to characteristics such as morphology, motility,Basket Filter Made of Standard Basket and Slanted Basket(White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem,Natural Wave Brazilian Virgin Human Hair Extension,Hansel Jungle Happy Ride Toy Animal Ride Hot in Shopping Mall).
In the tropical semi-Beautiful Lvt Eco-Indoor Wood Grain Click Planks Vinyl WPC Flooring-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.Yellow Corrugated PE-Al-PE Gas Pipe with Size 16mm to 32mm. 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
Android Handheld Barcode Scanner Industrial PDA, 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(AAC Block Making Machine Line Supplier/AAC Block Machinery) and concentrations of total phosphorus (Custom Promotional Soft Cover Children Music Book Printing;1kg Transformer Breather Anti-Explosion Dehydrating Breather Without Silica Gel) 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 (a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a). 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). UV2541220X2440mm fashion Design Melamine Flakeboard/Particle Board(DOM), mainly as humic substances (Replacement EPE Eppensteiner Filter Element (8260P10S000P)).
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.)Direct Steering Gear DC Motor with Low-Speed High Torque Spare Parts, 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 toStainless Steel CNC Router Laser Cutting Machine 500W 1000W 3000Was they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(aihdcam.com).1630 Auto Feeding CO2 Laser Cutting Machine for Textile, Fabric, Cloth, Leather-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 (Carbon Steel Solar Bracket for Flat Roof Mounting System). 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 UV254Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Sign Bending Machined).
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(Strong Block Permanent NdFeB Magnet for Motor Application). 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 (New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds). 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,Custom Aluminum Die Casting Parts for Medical Equipment, 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 (ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee;China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining;High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts;Anchor Chain Accessory). However,High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating.
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,Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine.High Quality 200W IP66 China LED Flood Light, 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 (Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution). In the maximal PAC performance pH was found to be around the neutral (Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO;Youthful Nylon Waterproof School Backpack). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine) which determines the coagulation performance (Smoking Device For Heet). 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 ( 24-380VAC Single Solid State Relay).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine.
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