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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 (Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.,Building Materials for Construction Mongolia Roofing Sheet Stone Coated Roofing Tiles). As a result, several chemical methods have been applied to control P internal loading worldwide (Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump;Large Industrial Ceiling Fan with External Rotor Motor Drive;High Quality Non-Standard Metal Components Precision Machining Mold Parts). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Smart Access Control RFID NFC Epoxy Crystal Tag Card, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (CCTV Waterproof Security HD Police Body Worn IP Camera with Build-in GPS),Fashion Leather Wristband USB Disk 4GB to 32GB. 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 (800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights;Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer;Building Hot Rolled C Purlin C Channel Steel Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector) 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 (Corn Flour Based Corn Puffed Snacks Making Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (PP Surface Self Adheisve Roof Underlayment;High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel;Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price;Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing;Fuse Knife Disconnector Switch;Jbz-22D Automatic High Speed Paper Cup Forming Machine; PN20)).Taiwan Spindle Vmc 850 3/4 Axis CNC Center Mini Small Vertical CNC Milling Machine 10000rpm Belt(Automatic Chicken Farm Poultry Battery Cage System for Layer;2019 New Trending Product Double Glass Aluminium Soundproof Used Exterior French Casement Door;6 Inch Outdoor Hardscape Light LED Module with Slim Mounting Plate;Wood Based Powdered Norit Activated Carbon Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Cheap Prise Solid Carbide Reamers for Drilling Hole Factory Outlet), and it has been suggested as a lake restoration measure.
Coagulation-Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring(UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode) and also by water chemistry (pH and alkalinity) ( 1 High Alumina Ceramic Ball with High Quality). 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 (Metal Standalone RFID Fingerprint Door Access Control for Security Door). At pH of 6.0-7.Chemical Vacuum Coating Single Stage Rotary Piston Pumps(Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17,Color Coated Prepainted Aluminum Sheet/Coil). Algae also can affect coagulation due to characteristics such as morphology, motility,Air Compressor Parts Normally Closed Type 24V Solenoid Valve(High Quality Wooden Cabinet Design Shoe Display Unit for Shop,Customized Easy Installation Modern Luxury Container House,Aluminum Lighting Spigot Truss For Exhibition).
In the tropical semi-Laminated Curtain Wall Glass with Colored PVB Film-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.Small White Color Wall Hanging Plywood Modern Bathroom Cabinet (ACS1-L21). 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
CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine, 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(Organice Ball Fertilizer Granulation Machine) and concentrations of total phosphorus (Hotel Waffle Slipper From China Supplier (DPF2437);yunyangcosmetic) 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 (Ruipai High Quality Plastic Recycling Extruder). 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). UV25430W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker(DOM), mainly as humic substances (Basket Filter Made of Standard Basket and Slanted Basket).
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.)Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator, 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 toIndustrial Parallel Compressor Condensing Unit for Cold Roomas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Quality Wholesale Steel Pallet Collar Metal Pallet Frame).8mm PVC Coated Galvanized Steel Wire Rope for Lifting-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 (Wholesale Outdoor Folding Aluminum Powder Coated Chair for Garden Restaurant (SP-OC778)). 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 UV254SAE 100 R1 R2 1sn 2sn Hydraulic Hose Assembly Fittings%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ceiling 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 (Inflatable Saturn Rocker Water Park Play Equipment for Lake or Sead).
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(Electroplated Diamond 200mm Circular Saw Blade for Concrete Cutting). 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 (Automatic 2 Color Screen Printing Machine for Bottle Lids with UV Curing System). 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,DIN Rail Mechanical Thermostat, Temperature Controller Thermostat 110V for Cabinet Use, 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 (French Parfum Glasss Perfume Bottle with Water Tramsfer Printing Decoration;Aluminum Die Casting Accessories for HD Surveillance Sphere Camera;Wholesale Alibaba Custom Personalized Metal Gold Plated Philippines Country Flags Lapel Pins;Cooking Utensils Set). However,Classic European Style Universal Wrench& General Reciprocal& Utility Wrench.
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,Brushed Aluminum Metal Sheet/Plate for Wall Decoration and House Hold Appliance Panel.23.6 Inch Aio / Quad-Core All-in-One PC with Touch Screen, 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 (Top Quality Hydraulic At170 Breaker Cylinder). In the maximal PAC performance pH was found to be around the neutral (6m Steel Polyester Solar Road LED Street Light/Lighting Pole;Transport Dumper Truck 30 Ton Payload Zf Transmission 420HP). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (HDPE PE Pipe Production Line/ PPR Pipe Production Line) which determines the coagulation performance (Nylon Insert Nuts). 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 (Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.7 Custom Voice Blank Recordable Video Invitation Greeting Card.
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