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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 (Small Industrial Sewage Treatment Unit for Industrial Wastewater Treatment,Galvanized Scaffolding Adjustable Solid Screw Jack with Base Plate). As a result, several chemical methods have been applied to control P internal loading worldwide (Low Cost Commercia Plastic Polycarbonate Used Agricultural Greenhouse for Sale; Disc-Chain Automatic Feeding System;20% White Vinegar Available for Agricultural or Cleaning Purposes). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Dart Extrusion Machinery Making Twin Screw Extruder). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Aluminum Square Bar, Aluminum Round Bar, Cutting Bar, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (50 Ton Long Stroke Crane Hydraulic Oil Cylinder),Fashion Sports Woven Wristband with Print Logo. 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 (100% Fabric Advertising Display See Through Mesh Banner Windproof;ATV Electric Winch with 3500lb Pulling Capacity (Star Model);1000bar Electric Water Cleaner Pump High Pressure Cleaner Pump). However alum may result in high concentration of residual Al and is strongly affected by temperature (ISO SGS Certified 100% Natural Spirulina Powder) 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 (Microwave Oven Bulbs). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (55 Inch Waterproof Digital Signage Outdoor LCD Advertising Display Monitor;OEM Manufacturer 6p6c 90 Degree DIP Type Rj11 Connector;Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball;Disposable Take out Paper Food Salad Sushi Lunch Box Container;Plastic Crown Moulding;99.95% Pure Metal Molybdenum Mo Sputtering /Sputter Target for Magnetron Sputtering;High Aluminum Insulating Ceramic Fiber Paper for Industrial Kilns).Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean(Plastic Stone PVC Faux/Artificial/Imitation Marble Skirting Profile Extrusion Line;Drawing Guide Styling Shaping Brow Grooming Makeup Set Eyebrows Stencils with 24 Different Shapes;Glass Water Bottle with Silicone Sleeve Silicone Rubber Cup Sleeve Silicone Sleeve;Outdoor 4 LEDs RGB Landcape Spotlight Solar LED Lawn Light) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1)), and it has been suggested as a lake restoration measure.
Coagulation-Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair(Eco-Friendly Natural Organic Bamboo Toothbrush) and also by water chemistry (pH and alkalinity) (Fire Retardant Fire Retardant Coating Diatom Ooze Used Sepiolite Powder Sepiolite Fiber Sepiolite). 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 (Promotion Custom Printed Logo Boys Kids Children′s Blank White T-Shirt). At pH of 6.0-7.Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion(Fiberglass Heat Fire Resistant Welding Welders Blanket Cover Protective Fabric,Fertilizer Binder and Dispersant Sodium Lignin Sulfonate). Algae also can affect coagulation due to characteristics such as morphology, motility,Household Thermometer Electronic Temperature and Humidity Meter Monitor(China Metal Cooling Fan for Dry-Type Transformer,Superior Fabric Core Conveyor Belts Vulcanizing Press From China,Low Cost CNC Carving Perforated Metal Fence for Outdoor Use).
In the tropical semi-China Food Fruit Vegetables Spiral Quick Freezer-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.FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia. 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
SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker, 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(Naked Mango Premium E-Liquid|Nicotine Salt for Electric Cigarette) and concentrations of total phosphorus (Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP);Yogurt Milk Filling 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 (1 1/4 Inch Abrasive Resistant High Pressure Sandblasting Hose 12bar). 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). UV254Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75(DOM), mainly as humic substances (Dumpling Wrapper Machine Dough Pressing Machine Dough Sheet Cutter to Do Tortilla Flat Bread).
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.)New Version Breakage-Proof Multihead Weigher for Biscuits, 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 to7 Liters Vertical Type Commercial Butchery Manual Sausage Filleras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aerial Cable Accessories Aluminum Parallel Groove Clamp for Bare Conductor).Log Debarker Veneer Rotary Peeling Machine-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 (Portable Animal High Frequency X Radiography Machine (HP-HFX600V)). 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 UV254IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Mold Design Non-Stick Silicone Waffle Maker Cake Mold). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Api 5l X60 Steel Piped).
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(Custom Stainless Steel Parts CNC Automotive Device Spare Parts CNC Milling). 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 (Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag). 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,DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval, 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 (Glass Shower Door Frame Waterproof Seal PVC Seal;2-Channel/4-Channel DC Current Voltage to RS232/RS485 a/D Converter;Cheap Bearing Rotary Fiber Laser Marking Machine Marker Laser Machine for Stainless Steel;Adjustable American Type Worm Gear Fuel Hose Clamp 8-12mm to All). However,Portable Solar Lantern with Built-in Solar Panel.
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,Asphalt Pavement Bitumen Road Crack Seal Equipment.Rk Aluminum Exhibition Stage Truss Booth Stand Lighting Truss, 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 (12mm Multiwall Green Perforated Hollow Polycarbonate Sheet). In the maximal PAC performance pH was found to be around the neutral (Best Quality Tianeptine Acid / Tianeptine CAS 66981-73-5;Chiller Price Water Cooling System Screw Air Cooled). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (1.0m 4CH Wireless NVR Alarm Security CCTV Kit with 10 LCD Monitor 1tb HDD) which determines the coagulation performance (Cnc Turret Punching Press Factory OEM/ODM Products). 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 ( NdFeB Magnet for Motor (N38H)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stable Steel Flat Glass Transport Rack with Safe Support Protection.
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