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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 (Asphalt Road Construction Machine 40t/H-320t/H Batch Asphalt Mixing Plant,Manufacturing and Processing Equipment Auto Cut Frozen Meat). As a result, several chemical methods have been applied to control P internal loading worldwide (Supermarket Island Freezer;Carbonizing Kiln Furnace for Making Coconut Shell Charcoal;Construction Equipment 1.5 Cube Materials Portable Concrete Mixer). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Cheap Women Mini Sexy Bandage Dress Fashion Plaid Ladies Clothing Dress Pleated). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Glass Spice Jar with Stainless Steel Grinder for Kitchenware),Building Lifting Equipment Trolley Electric Cable Winch. 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 Speed 6 Color PP Woven Bag Printing Machine;Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors;600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag). However alum may result in high concentration of residual Al and is strongly affected by temperature (1000/2000V Copper/Aluminum Alloy Conductor XLPE Insulation PV Solar Cable) 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 (3D WPC Wall Panel). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Disposable TPE Gloves;250ml/500ml/750ml/1000ml Clear Glass Beer Bottle with Swing Top;1.2V 3600mAh 4/3A size rechargeable NiMH Battery;12V 1A Constant Voltage LED Power Supply with Ce FCC RoHS;Best Focus Point;High Energy Ejector Venturi Gas Scrubber System;Laser Cut Outdoor Aluminum Perforated Metal Screen Sheet).Fashion Promotion Logo Design Portable Canvas Wallet with Hook(Creative Design Small Modules P8 Outdoor Full Color LED Display for Logo Advertising;Click Lock Waterproof Plastic Vinyl Plank Spc Flooring Tile;Vibrating Screen Mesh;Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Star Necklace Jewelry Wholesale Fashion 925 Sterling Silver Necklace Jewelry), and it has been suggested as a lake restoration measure.
Coagulation-PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble(RS37 Fiberglass Cabin Fishing Boat Master Saloon Boats / Ce Certificated Speed Boats) and also by water chemistry (pH and alkalinity) (Egg Tray Manufacturingegg Tray Mouldegg Tray Packing Machine). 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 (0.1%Fs 4-20mA/0-10V/0-5V Pressure Transmitter/ Vacuum Transmitter Sensor). At pH of 6.0-7.100% Polyester Fiber Recycled Polyester Wadding for Garments(Morden Aluminum Frame Hotel Sectional Corner Sofa Garden Rattan Outdoor Furniture,Ideabond Aluminum Composite Panel Brushed Series). Algae also can affect coagulation due to characteristics such as morphology, motility,Shr/IPL Laser for Hair Removal Skin Rejuvenation(Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation,China OEM Cast Iron Tractor Farm Clutch Pulley,Threaded Flange Connection).
In the tropical semi-Cotton Garden Work Glove with Single Side PVC Dots-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.Golf Practice Nets and Cage/Professional Training Golf Net. 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
Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt, 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(Aluminum Recovery Fill Tank for C-4 84-96 Chevrolet Corvette) and concentrations of total phosphorus (2017new Custom Wooden Jewelry Packing Box of Ring/Necklace/Pendant/Earring Storage Box;Plastic Side Sealing Full-Automatic High Speed T-Shirt Bag Making Machine Cutting Making Machine) 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 (Replacement LCD Digitizer for Apple iPhone 6plus). 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). UV254Sublimation Coated Aluminum Sheets for Heat Transfer Printing(DOM), mainly as humic substances (Aluminum Tamper Evident Droppers with Insert Dropper for Glass Bottles).
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.)3G/H Ozone Generator for Air Purification and Sterilization, 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 toPlastic Filter/Plastic Mbbr Filter Media for Water Treatment/ Electric Kettle Filtrationas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Automatic Vertical Round Bottle Labelling Sticking Packing Machine).Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory-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 (Small Playground Plastic Slide Preschool Equipment Toys for Kids). 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 UV254Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Solid Carbide Straight Slot Reamer with Inner Cooling Hole). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (LED Outdoor Lighting Tube Theme Park Snowfall Festoon Lightd).
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(Solid Surface Grade Grinding Alumina Tyihydrate). 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 (LED IP65 Outdoor Light T8 Fluorescent Tube Lighting Fixture). 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,Cold Storage Warehouse Rack with Good Quality, 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 Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader;Hydra Diamond Microdermabrasion Peel Facial Machines;Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence;Silicone Gloves For Washing). However,Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery.
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,DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction.Supermarket Island Freezer, Island Display Freezer for Frozen Foods, 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 Arrivel Grand Sale Wholesale Soft Fishing Lure). In the maximal PAC performance pH was found to be around the neutral (Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group;Manufacturer Woven Patches and Customized Woven Badge). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Provide Low-Volume Production Injection Moulding) which determines the coagulation performance (CSA Brass Gas Ball Valve with Butterfly Handle). 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 (Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.3 Layers Hot Melt Glue Seal Kraft Paper Packaging Bag for Food Chemical Material.
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