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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 (High Quality Electrochromic Pdlc Privacy Film,New Ce CB Approved Garment Steamer China Manufacturer). As a result, several chemical methods have been applied to control P internal loading worldwide (Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components;Water Resistant Rubber Gasket for Industry;Mirror Chrome Aluminium Powder Gold Silver Pigment for Nail Art). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,220V Square Synchronous Grill Rotisserie Motor for Gas Cooker, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Professional Injection Molding Manufacturer),5r 200W LED Moving Head Beam 3 in 1 Stage Lighting. 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 (OEM/ODM Custom Precision Copper/Aluminum /Bronze /Carbon Steel/Stainless CNC Machining Parts;Showbull Professional 5800 Gasoline Wood Cutter Chainsaw Made in China;New Design Contact Infrared Baby Ear Thermometer Jl0158). However alum may result in high concentration of residual Al and is strongly affected by temperature (Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System) 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 (Full Semi Automatic Loading Tube Fiber Laser Cutter Patent Design). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Speed Automatic Cleaning Scourer Making Machine Manufacturer;Agricultural Sprinkler Irrigation System Oscillating Impact Sprinkler for Garden;6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper;Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine;Anti Corrosion Pvc Roofing Sheets;20K Ohhm 1% Electrical Ntc Thermistor Resistance;OEM Customized Aluminum Die Casting Automotive Parts Die Casting Die).Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult(Hex B19 B22 Integral Drill Rod Steel /Shank Drill Road/Tapered Drill Rods; Truck Parts;Super Click Vinyl Flooring Interlocking Floor Rigid Core Vinyl Plank Spc;16oz Pet Plastic Food Jar with Embossed Metal Lid (PPC-PJ-1701)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding), and it has been suggested as a lake restoration measure.
Coagulation-Steel Structure Welding Steel Structure Metal Building(Custom Design Stainless Steel Sheet Metal Fabrication Box Cover) and also by water chemistry (pH and alkalinity) (Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula). 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 High Quality Muslim Bridal Wedding Dress). At pH of 6.0-7.Chc-B07 Health Stainless Steel Germanium Bracelet for Female, Oppbag(Cartoon Design Decorative PVC Sheet for Wall Panel Moulding, Skin Care). Algae also can affect coagulation due to characteristics such as morphology, motility,92 16: 9 Motorized Projection Screens with Black Casing(3003 3004 3005 Aluminium Circles for Foil Pans with Lids,All Round Inflatable Stand up Paddle Boards for Surfing,Portable Home Use RF Skin Tightening Machine for Double Chin Removal).
In the tropical semi-Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes-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.Colorful LCD Display High Quality Cheap Price Optical Fiber Fusion Splicer, Splicing Machine S6. 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
15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale, 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 Stick Welding Electrodes E6013&E7018 Stone Bridge Brand) and concentrations of total phosphorus (Compact Laminate Kids Urinal Screen with Good Price;12-24W LED Work Light Bar Flood Spot Combo Driving Lamp Car Truck Offroad 12-85V) 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 (Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63). 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). UV254Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette(DOM), mainly as humic substances (New Product PVC Insulation Tape).
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.)Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885), 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 to57-5 Micron Micro Powder Mill Pulverizer Grinding Plantas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(1100).5 Colors Sticker Label Flexographic Printer-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 (Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.). 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 UV254Duct Outdoor Single-Mode Gyfy Fiber Optic Cable%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (3 Pin Multi Plug Socketd).
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(High Quality Non-Standard Metal Components Precision Machining Mold Parts). 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 (Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing 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,Aluminium Spigot Lighting Truss, Stage Truss, Roof Truss for Sale, 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 (Building Hot Rolled C Purlin C Channel Steel Price;Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector;PP Surface Self Adheisve Roof Underlayment;PDC Diamond Enhanced Mining Pick Tool for Hard Rock Tunneling Excavation). However,Wood Acrylic Ss CO2 Tube CNC Laser Cutting Machine for Metal and Nonmetal.
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,Customized Small Module Sintered Metal Product Spur Gear Pinion.High Tensile Sharp Razor Barbed Wire for Security Fencing, 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 (High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel). In the maximal PAC performance pH was found to be around the neutral (Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price;Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Jbz-22D Automatic High Speed Paper Cup Forming Machine) which determines the coagulation performance (Coms Camera Factory Vari-Focal Lens DVR Camera Web Camera Bullet). 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 ( PN20)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Ce Certification Jigging Machine for Manganese Ore Extraction/Manganese Ore Refining Machine.
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