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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 (Hot Selling 30W Fractional CO2 Laser Vaginal Tightening Machine,Customized Easy Installation Modern Luxury Container House). As a result, several chemical methods have been applied to control P internal loading worldwide (Electronic Writing Board Finger Touch Infrared Interactive Board for Interactive Kids Games;Cmyk Printed Colorful Logo Wholesale Luxury Fancy Art Paper Shopping Gift Bag with Ribbon;Ductile Iron Grooved Rigid/Flexible Couplings Fire Fighting Pipe Fittings). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Professional Effective Shockwave Belly Fat Removal Machine/ Shockwave Slimming). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Reflective Tape Protective Nomex Fire Suit with Trousers, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Crepe Paper Automatic Masking Tape (YST-MT-004)),RF Wrinkle Removal IPL Hair Removal Skin Rejuvenation Beauty Salon Equipment with Filter. 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 (Horizontal Flat Bed CNC Metal Lathe (CAK6140 CAK6150);2019 LCD PRO Hot Ionic Straightening Brush (Q20);SMD P4 Outdoor Full Color Rental HD LED Display). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine) 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 (Concertina Flat Razor Barbed Wire Cbt-65 Carton Box). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wicker Willow Flower Garden Gardening Basket;New Fitness Commercial Exercise Spinning Bike;Pressure Sensor Water Level Pressure Transmitter;7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System;Taper Roller Bearing;E-Bay Hot Sales Silicone Baby Dolls for Kids Toys;Bendable IP67 Waterproof Neon Flex LED Light with Silicone Tube).Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment(Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles;Aluminium Profile Wood Color Tilt and Turn Casement Windows and Stainless Screen Doors;m.vibratemotor.com;Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (New Arrival Household Self-Washed Flat Mops Cleaning), and it has been suggested as a lake restoration measure.
Coagulation-Best Brush Customized Synthetic Flat Foundation Makeup Brush Professional Cosmetics Accessory(Chinese Furniture Outdoor Garden Furniture Aluminum Sofa Sets) and also by water chemistry (pH and alkalinity) (Sino Heavy Duty Truck HOWO Parts Lowest Price Rear Shock Absorber with Wg1642440021 From manca). 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 (Hot Sale Disposable Lab Plastic Petri Dishes with Lids). At pH of 6.0-7.Continuous 1-4 Lines Cij Batch Number Automatic Industrial Inkjet Printer(Breathable Pet Dog Shoes with Reflective Magic Tape Straps,2018 Newest 12inch Music Sound Box for Computer). Algae also can affect coagulation due to characteristics such as morphology, motility,Custom Printed Sublimation Printing Fit Yoga Pants Leggings(Customized Cutting Tool Solid Carbide Tool Taps (TS-100002),Cyclone Mesh Turbo Diamond Saw Blade for Ceramic Tile,Carbon Steel Fuel / Petrol / Gasoline /Crude Oil Tanker for Storage).
In the tropical semi-Customized Wholesale Waterproof Crossbody Chest Bag Backpack Sling Bag Women Messager Shoulder Bag-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.Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester. 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
Licensed Mercedes-Benz Gtr 2 Seats Children Car in Black, 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(Closed Cargo Box Garbage Truck/Rubbish Collector Diesel Engine Tricycle) and concentrations of total phosphorus (High Quality Antibiotics Powder Enrofloxacin CAS 93106-60-6;Agricultural Bearing Factory OEM/ODM Product) 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 (OEM Stamping Welding Metal Frame Box Parts for Steel Fabrication). 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). UV2547, 5kw High Effficient AC Motor as EV Conversion Kit(DOM), mainly as humic substances (Biodegradable Packaging Small Plastic Compartment Storage Box for Food).
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.)2019 New Style Plastic Toothbrush with Cheap Price for Hotel Use, 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 toColored Corrugated Steel Roofing Sheet with ISO9001as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hot Sell Quality 100% Human Hair Afro Kinky Virign Hair).Filter Press Small-Size Metal Plate Hydraulic Press Machine-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 (FRP Fiberglass Underground Septic Tank for Effluent Treatment). 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 UV254JL 155cm Life-Size Real Perfect Asian Shemale Sex Doll Torso for Man%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (96 Pin IDC Cable Connector D-SUB Connector SCSI Type). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Lauryl Dimethyl Amine Oxide Cas Supplier & Manufacturerd).
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(OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated). 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 (Steel Jacket Steam Insulation Pipeline Production Best Quality). 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,Eastcooler 10X2.5 Water Filter Granular Active Carbon Filter Cartridge, 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 (Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825);Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car;Smelting Furnace Dust Collector Fiberglass Bag Filter;Shower Column with Fashionable Black Color (LT-X155)). However,Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer.
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,Original Monitor Display Panel for Cat320d Excavator.Fanuc CNC Vertical Milling Machine 3 4 Axis, CNC Milling Machining Center, CNC Milling Machine (VMC850), 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 (China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop). In the maximal PAC performance pH was found to be around the neutral (Electronic Smoke Digitizer Quartz Atomizer Short Quartz Tube;Sell High Quality Food Grade Sodium Carboxymethyl Cellulose CMC). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (European VDE Schuko 3-Pin Waterproof IP44 Power Plug) which determines the coagulation performance (Horizontal Bead Mill in Coating). 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 (Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Aluminum CNC Al5052 / Al6061 / Al6063 Machining Turning Parts for Mil-Spec Electronics.
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