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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 (Clear Plastic PVC Window Cmky Full Color Printing Box,Electric Single Phase Fan Motor 220V 85W with Plastic Cooling Fan). As a result, several chemical methods have been applied to control P internal loading worldwide (Good Quality Brow Pencil Pencil Private Label Wholesale;Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic;Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Jingsun off Grid 100kw Solar Power System for Project). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Mini Horizontal Axis 100W Wind Generator Turbine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (m.ldkchina.com),programmable LOGO printing 13.56MHz ICODE ILT PVC RFID smart card. 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 (RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp;Very Cute Baby Gift Packing Shopping Carrier Paper Bag; Cookware Set with Hammer Pattern). However alum may result in high concentration of residual Al and is strongly affected by temperature (Mimaki Jv5/Jv33/Jv300/Ss21/Sb53 Permanent Ink Cartridge Chips) 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 (Automatic Plastic Fork Spoon Knife Serviette Cutlery Packing Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Solid Surface Stone Table Top Restaurant Black Round Dining Tables;Custom Printed Plastic Soft Vinyl PE Ziplock Packaging Bag;Balcony Terrace Roof Canopy with Aluminum Frame;Coolsour Air-Conditioning Compressor Crankcase Silicone Rubber Heating Strip;Good Ventilation Fully-Auto L-Bar Sealer Shrink Tunnel for Software;Chain Rigging Clip U Bolt Saddle Cable Clamp; High Temperature Boiler Steel Pipe Tube ASME SA335 P22 P 91).Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable(Used 48cavity Cool/Hot Runner Cutlery/Spoon Plastic Injection Mould;3 Axis Vertical CNC Cutting Milling Drilling Machine Tool Center;Diesel and Oil Heated Car Spray Paint Booth Auto Painting Equipment Heated Paint Booth;Surface Paiting Line UV PU Water Base Spraying Robot Arm) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box), and it has been suggested as a lake restoration measure.
Coagulation-Customized Normal Temperature Feed Channel Cylinder for Stacker Reclaimer(Rubber Raw Material Kneader Machine -75L Banbury Mixer) and also by water chemistry (pH and alkalinity) (Cheap China 2 Inch Wafer Stainless Steel Butterfly Valve). 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 (OEM Sand Casting Part Slag Ladle for Mine Casting). At pH of 6.0-7.Thin Wall 7049 7050 Aluminum Tube with PVC Package(The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture,DIN7504 Stainless Steel Self Drilling Drywall Screw). Algae also can affect coagulation due to characteristics such as morphology, motility,Impa651710 Marine Wholesale Seawater Thermometer( Construction Pipes Price,Synthetic Filament Spunbonded and Needlepunched Nonwoven Geotextiles,m.jmheatexchanger.com).
In the tropical semi-Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)-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.Breathable Pet Dog Shoes with Reflective Magic Tape Straps. 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
Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker, 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(3-Wheel Motorcycle with 1500W Motor and EEC Certificate) and concentrations of total phosphorus (10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom;A4 Double Sides Mini Teaching Writing Dry Erase White Board for Kids) 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 (25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake). 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). UV254Best Price 1325 Woodworking CNC Router Machine Equipment(DOM), mainly as humic substances (Medical Infusion Pump for Human and Veterinary with Fluid Warmer).
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.)8FT Wood Log Debarker Machine for Plywood Machinery, 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 toFront Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(China Head Laser Beam).OEM Hardware Factory Custom Fabrication CNC Aluminum Signet-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 (Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer). 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 UV254on-off Automotive Switches Automotive Rocker Switch 16A Rocker Switch%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Reflecting Aluminum Film Vacuum Evaporation Coating Equipment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Brightness Neon Tube Swimming Pool LED Strip Lightingd).
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(Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings). 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 (China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal). 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,Youthful Nylon Waterproof School Backpack, 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 (Foil Induction Sealing Machine for Glass Plastic Bottle Jar;Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials;3D Silver Reflective Custom Heat Transfer Label Garment Label;Potassium Ferrocyanide 99%). However,Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag.
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,2018 Newest Camping Hiking Bug Net Hammock.Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine, 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 (Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove). In the maximal PAC performance pH was found to be around the neutral (England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification;Lash Camellia Ellipse Flat Eyelash Extension Makeup Tool Lashes Extensions 102). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers) which determines the coagulation performance (Pull String Music Box). 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 (Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Commercial Clean Room Spc Vinyl Waterproof Stone Plastic Composite Flooring Plank.
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