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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 (Carbon Steel Solar Bracket for Flat Roof Mounting System,Simple Installation Compact Ns Types Molded Case Circuit Breaker in Electrical). As a result, several chemical methods have been applied to control P internal loading worldwide (Gi Steel Sheet Galvanized Steel Sheet Zinc Coated Plain Steel Sheet;Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench;Strong Block Permanent NdFeB Magnet for Motor Application). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Type Automatic Multihead Weigher All-in-One Packing Machine for Seeds). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Antitheft UHF Alien H3 RFID Smart Jewellery Sticker Tag Anti Theft RFID Label, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Double Phoenix G Point Sex Vibrator AV Penis for Female Masturbation Flirting Sex Dildo),Deboner Machine to Separate Meat and Bone/Automatic Poultry Separator/Poultry Deboning Machine. 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 ( Telehandler Price;Automatic Pesticide Bottle Blowing/Making Machine;ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Factory Processing Auto Car Accessory Motor Computer Part by CNC Machining) 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 (Bearing Accessories Bearing Ball Bearing Rollers). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Aluminum Alloy Sand Casting Gravity Casting Aluminum Parts;Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution;Professional 808nm Laser Diode Hair Removal Machine/Epilator Device with Ce/ISO;Youthful Nylon Waterproof School Backpack;18w Pd Wall Charger For Iphone 11;2000kg/H Automatic Onion Chopper Slicer Slicing Cutting Processing Machine; 24-380VAC Single Solid State Relay).Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368(Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory;Used Tire Reclaimed Rubber Machine / Rubber Sheet Making Machine;Wall Mounted 7.68 Kwh for Home Energy Storage System;Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress), and it has been suggested as a lake restoration measure.
Coagulation-PC Extrusion LED Shell Transparent PC LED Shade Cover/Clear PC Lamp Shade(Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows) and also by water chemistry (pH and alkalinity) (Shockwave Therapy Machine Shock Wave Physiotherapy Equipment Air Pressure Shockwave Sw10). 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 (Best Seller Popular Women Customized Grey Workout Leggings). At pH of 6.0-7.Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw(Steel Toe Cap Men Leather Safety Shoes Footwear Ufe019,New Design Artificial Leather Fabric PVC Leather for Furniture (1008#)). Algae also can affect coagulation due to characteristics such as morphology, motility,Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor(Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning,Dx51d China Pre-Painted Galvanized Steel PPGI /PPGL Steel Sheet for Roofing Z20-Z275,Foundry Pouring Systems Pouring Ladle with Price).
In the tropical semi-High Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12-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.High Energy Wet Pulverizer and Wet Powder Mill. 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
Waterproof and Moldproof Marble Floor Grouting, 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(High Quality Customized Printed Bottle Holder Lanyard Strap NFL Olympic) and concentrations of total phosphorus (Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order;Hot Selling Household Cleaners Laundry Detergent Powder) 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 (Pre-Heated Copper Coil Pressure Solar Water Heater Equipment). 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). UV254Round Pipe Welded Pipe Middle Size for Chemical Companies(DOM), mainly as humic substances (Empty Clear Glass Olive Oil Bottles Used for Filling Custom Square Glass Bottle Wholesale).
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.)Incoloy 825 Pipe for Industry Application, 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 to20W Fiber Laser Marker/Engraver/Cutter for Metal Seal/LED Log/Anti-Dazzling Screenas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(m.sajoo-switch.com).Dock Leveler Hydraulic Motor Hydraulic System and Power Pack-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 (Factory Directly Sale Virgin Kraft Liner Paper Machines). 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 UV254China Rotary Kiln for Sponge Iron with Competitive Price with 0.9-42tph%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Special Offer Stock Primary School Uniform Shirt for Boys). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (3 Step Stool Household Aluminum Ladder Metal Folding Ladders with Handraild).
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(Picnic Lunch Bag Waterproof Tote Lunch Bag for Kids Adult). 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 (Jinma 254 Yangdong Y385t Water Pump Yangdong Engine Parts). 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,Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel, 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 (Dto0032 Foldable Outdoor Indoor Nylon Mesh Hammock;Beautiful Christmas Printed Gift Polyester Grosgrain Ribbon Satin Ribbon;Custom Stand up Composite Material Zipper Packaging Bag Candy Bag;Medical Mask Machine). However,Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356).
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 Unique Design UV Printing Phone Case for Apple iPhone 8, for iPhone 8 Mobile Phone Shell.New Design Infrared Touchless Automatic Sensor Electric Water Faucet, 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 (New Model Solar Room Lighting System Lighting Kit Light in Remote Area). In the maximal PAC performance pH was found to be around the neutral (Lacquered PVC High Intensity and Good Elastibity Tarpaulin;Factory Wholesale T5 T6 7075 6061 6063 Alloy Aluminium/Aluminum Sheet Plate). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Asphalt Mixing Plant) which determines the coagulation performance (China Factory High Quality Open Mesh Fabric Used in Drying Machine). 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 (with Pneumatic Actuator + Limit Switch Box Ball Valve (Q641F)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Single-Phase Electric Motors Capacitors 110V 270-324mfd.
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