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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 (Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8,Water Purifier Membrane). As a result, several chemical methods have been applied to control P internal loading worldwide (Forging SAE4140 S31803 Steel Crusher Eccentric Shaft;Car Repair Equipment Underground Garage Lift with Double Scissor Lifts;Building Material Colorful Stone Coated Metal Spanish Roofing Tile). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Auto Price Crankshaft Position Sensor 90919-05043). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom C3 C5 Ground Miniature Ball Screw 0802, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Jzr350-Dh Horizontal Type Cement Blender Concrete Mixer in Cameroon),Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding. 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 (Duplex Hydraulic Oil Filter for Lubrication System;Travel Luggage Scale with Tape Measure Function;Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V). However alum may result in high concentration of residual Al and is strongly affected by temperature (4 Fibers Wall-Mounted FTTH Distribution Box) 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 (14years Factory Tapioca Powder Weighing Filling Bagging Sealing Packing Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (80kw Electric Canopy Diesel Generator Powered by Cummins with Ce/ISO;Vehicle Wheel Anti-High Temperature Zirconia Ceramic Seal Pump Impeller;Water Park Outdoor Playground with Water Spray Device for Sale;Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift;Plywood Turn Over Machine;1/2 Inch Brass Stem Handwheel Gate Globe Valve;Commercial Coffee Roasters for Sale 1kg 3kg 6kg 12kg 120kg Coffee Roaster Machine Manufacturer).Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933(Perforated Decorative Aluminum Metal Curtain Wall Single Panel Sheet for Curtain Wall Decoration;Waste Pet Plastic Bottle Crushing Washing Recycling Machine;tonyearchem.com;Glass Mike Bottle 200ml 250ml with Screw Cap Straws) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Liquid Laundry Detergent Small Single Bag Packing Machinery), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress(2019 Shenzhen CNC Machining Companies CNC Small Aluminum Part) and also by water chemistry (pH and alkalinity) (Cee/IEC 32A 5p 400V 3 Phase European Standard Plug). 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 (Customized Rice Bowl With Lid). At pH of 6.0-7.Paint Spray Booth Air Flow Vehicle Paint Booth for Sale(Semi-Automatic Hydraulic Leather Football Machine,15 Inch IP65 Waterproof Industrial Touch Screen Monitor). Algae also can affect coagulation due to characteristics such as morphology, motility,High Purity Calcined Alumina Micro Powder for Ceramics Refractories(Modern Style Prefabricated Steel Structure Poultry House, Splicing Machine S6,Head Metal Waterjet Cutter CNC Cutting Machine for Price).
In the tropical semi-Customized Dummy Animal Teething Toy Design Baby Pacifer-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.Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings. 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
Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches, 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(Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes) and concentrations of total phosphorus (Floor Mounted Glass U Clamp Channel for Glass Balustrade;Malodorous Exhaust Gas Purification Treatment Equipment) 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 (Automatic Small Round Bottle Water Washing Filling Capping Machine). 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). UV254Automatic Concrete Paving Interlocking Block Brick Making Machine(DOM), mainly as humic substances (MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration).
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.)Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows, 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 toHot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plateas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Ball Post Cap).Plastic Injection Moulding for Plastic Car Toys Products, Truck Parts-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 (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag). 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 UV254Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valve%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (GRP FRP Fiberglass Composite Pressure Filter Oil Filterd).
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(Hydraulic Metal Hole Digger Punching Machine (CH-80)). 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 (Factory Customized Marathon Athletics Football Awards Medallion Metal Medal). 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,GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving 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 (Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale;Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride;Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light;Second Hand High Quality Taiwan Chenhsong Sm120ts Injeciont Machine). However,Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine.
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,Samsung 46 49 55 LCD video wall Samsung LCD screen.Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal, 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 (3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten). In the maximal PAC performance pH was found to be around the neutral ( Grass Cutting Machine;Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price) which determines the coagulation performance (Quality Fashion Custom Jewelry Choker Pendant Necklace). 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 (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Non Alkali Glassfiber Yarn for Weaving Electric Cable.
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