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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 (Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp,8 Way DC32V Circuit Car Trailer Auto Blade Fuse Box Block Holder Atc ATO 2-Input 8-Ouput). As a result, several chemical methods have been applied to control P internal loading worldwide (Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner;New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges;Cool Room Condenser and Evaporators Condensing Unit Prices Small Condensing Unit). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hf Vacuum Dryer Machine with Advanced High Frequency Technology). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Soft Tube Plastic Cylinder Round Bottle Screen Printing Machine Silkscreen Machinery, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China 2 Wheel Electric Scooter Motorcycle),High Security Bluetooth Bicycle U-Lock Smart Foot Flex Cable Gate Lock. 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 (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine;700mm RP HP UHP High Quality Graphite Electrode;Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch). However alum may result in high concentration of residual Al and is strongly affected by temperature (Furniture Laminate Sheet/HPL Panel/Building Material) 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 (Samsung Parts). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (7;Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale;Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant;Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1;7 Wire 11.11mm Prestressed Concrete PC Strand with ASTM A416;UV Digital Flatbed Printing Machine Seiko-1024;New Mini Loader Radlader Mini Zl936 Wheel Loader).Stable Steel Flat Glass Transport Rack with Safe Support Protection(High Quality Compair Air Compressor Air Filter 50273;OEM Custom Precision CNC Machined Steel Parts;Swimming Pool Heat Pump Water Heater with R410A Refrigerant;Professional Supplier of Hot Rolled Steel U Channel) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop), and it has been suggested as a lake restoration measure.
Coagulation-Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine(Multi-Layer HDPE PE PPR Pipe Production Line) and also by water chemistry (pH and alkalinity) (400W Vertical Axis Windmill Generator (200W-5kw)). 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 (Single Facer Carton Box Packing Machine). At pH of 6.0-7.Silicone Grip Hand Forearm Strength Gripper Multi Colors Weights Rubber Ring Exerciser Gym(Auto Part PDC Parking Sensor for BMW 66209261595,Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank). Algae also can affect coagulation due to characteristics such as morphology, motility,35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck(Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush,Kfc Macdonald Food Grade Convenient Disposable PE Glove,m.triround-inox.com).
In the tropical semi-Foshan Manufacturer Sound Proof Powder Coated Aluminum Bi-Folding Door with Australia Subframe-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.Fertilizer Binder and Dispersant Sodium Lignin Sulfonate. 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
Reducer Hydraulic Fitting with Swivel Nut (2D), 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(OEM 2019 Custom Fashion Men Black Embroidered Crew Neck Sweatshirt with Embroidered Rose) and concentrations of total phosphorus (Custom Aluminum Steel CNC Machining Mechanical Turning Parts;China Automatic Machine Veneer Peeling) 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 (Galvanized Wire Fence Building Barbed Wire Fence Pictures). 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 Design Commercial Plastic /Po Film Greenhouse for Tomato and Vegetable(DOM), mainly as humic substances (Fiber Laser Marking Machinery for Engraving Ribbon Metal Stainless Steel).
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.)Novel Designed Panel Steel Corrugated Metal Roofing Sheet Roll Forming Machine, 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 to35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truckas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(3 Tiers Chicken Broiler Cage).UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1-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 (Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring). 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 UV254Bright Polished Galvanzied Common Iron Wire Nails%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Agricultural Parts L Type Rotary Tiller Blade Wholesaler Quotes & PriceListd).
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(All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J)). 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 (High Speed Metal Pipe Automatic ERW Welded Pipe 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,Factory Direct Price Automatic Snack / Candy Grain Packing Machine, 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 (High Pressure Zirconia Ceramic Piston Rod Pump Ceramic; Skateboard Shoes;Kids Electric Car with 12V Battery Remote Control;cnmirant). However,Online pH TDS Ec Controller Digital Electrical Conductivity Meter.
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,Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon.V9 37kw 220V 380V Various Motor Type Control Flexible and Adaptable AC Drive, 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 Wehappy Silicone Baby Training Toothbrush Set with Blister Card Package). In the maximal PAC performance pH was found to be around the neutral (Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308);Auto Parts for Plastic Products Injection Mould Mold Tooling). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (904L Stainless Steel Press Sheet with Hl Surface Finish) which determines the coagulation performance (Waterproof Picnic Beer Can Ice Cooler Bag). 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 ( Cutting Bar).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Recessed Colorful Solar Interaction LED Underground Lighting.
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