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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 (Outdoor Food Meal Heating Bag for Travelling and Camping,CNC Machining Turning Part for Japan Market Suzuki Motorcycle Parts). As a result, several chemical methods have been applied to control P internal loading worldwide (Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra;Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508;430 Black Mirror Decorative Stainless Steel Sheet in Foshan). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) ( Door). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (crusher plant),Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion. 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 (Square Shape Glass Perfume Bottle Refillable Glass Perfume Bottle Atomizer Mist Bottle;Atex Approved Level Measuring Instrument Level Sensor; LPG Hose Best Choice for Home Use). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire) 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 (Camping Hammoc). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale Foldable Desk Silicon Mobile Phone Stand;10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine;Bright Solar Power Outdoor LED Light Motion Activated Light for Garden Patio Path Pool; Table Gas Stove;Reflective Conspicuity Tape for Vehicle Traffic Sign Reflective Material;API-5CT Standard Seamless Steel Pup Joint /Oilfield Services;Custom Lf 125kHz/Hf 13.56MHz Pet/PVC RFID Contactless Smart Card with Cheap Price).Household Thermometer Electronic Temperature and Humidity Meter Monitor(Supporting DDR4 RAM Intel Core I5 Mini PC Computer;Vodafast A2 Stainless Steel Channel Nuts with Long Spring;Garlic Chili Pepper Curry Ginger Ketchup Tomato Mayonnaise Food Packing Machine;Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Custom Aluminum Stainless Steel 90 Degree Angle Brackets), and it has been suggested as a lake restoration measure.
Coagulation-China Food Fruit Vegetables Spiral Quick Freezer(5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter) and also by water chemistry (pH and alkalinity) (Aluminum/Cooper/Galvanized Tube Precision Pipe Making 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 (Power Clean Power Washer Pressure Washer Pump). At pH of 6.0-7.FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia(4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s,OEM Aluminum Cutting Welding Stamping Shaping Fabrication). Algae also can affect coagulation due to characteristics such as morphology, motility,SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker(Outdoor WPC Wood Plastic Composite Fence Board with High Quality,Fiberglass Water Park Spray Playground Equipment for Sale,Trolley Cart).
In the tropical semi-Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75-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.New Version Breakage-Proof Multihead Weigher for Biscuits. 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
Log Debarker Veneer Rotary Peeling 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(CO2 Laser Engraving Cutting Machine for Acrylic) and concentrations of total phosphorus (Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter;Cartoon Animal Sunglasses) 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 (Outdoors Gardne Solar LED Wall Spot Lights with Smart Sensor). 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). UV254IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor(DOM), mainly as humic substances (Movable Oxygen Concentrator of Making High Purity O2 Gas Instead of Psa System).
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.)DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval, 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 toPP Square Nail Clip Flat Cable Clips White & Black 14mmas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Party Favors Biodegradable White Individual Packing Paper-Wrapped Paper Drinking Straws).Portable Solar Lantern with Built-in Solar Panel-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 (China Digital Type Lithium Battery Crush Testing Machine Price). 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 UV254Asphalt Pavement Bitumen Road Crack Seal Equipment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (38cc Petrol Chain Saw Wood Cutting Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PLC Automatic Rubber Internal Banbury Mixer & Hydraulic Rubber Kneaderd).
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(2019 Hottest Vapor Storm Disposable E-Cigarette Flavored Vape Pen). 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 (Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board). 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,Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss, 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 (Stainless Steel Expanded Metal Mesh for Industrial;New Product Automatic Powder Machine for Filling and Packing Spices;Portable Marking Machine Table for Height Adjustment;dmgstainless). However,3 Axles 60 Tons Excavator/Bulldozer/Loader/Paving Machine/Paver/Crane Low Bed Semi Trailer.
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,2019 Bdu Army Camouflage Uniform with 3-Color Desert Color.Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery, 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 (Wholesale Universal Sunproof Waterproof Silver Folding Auto Car Window Cover). In the maximal PAC performance pH was found to be around the neutral (Prefab Poultry Shed Designed and Constructed for One Stop;PVC Plank /Spc Click/ Popular PVC Flooring/DIY Flooring/Building Material/Vinyl Floor/Tile/Plank). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Construction Equipment Full Automatic Concrete Block Making Machine) which determines the coagulation performance (TUV/Ce Certified All Black Dual Glass Solar Panel 350W Mono with A Grade Solar Cells). 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 (for Toyota USB Car Charger with Audio Input/Adapter).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck.
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