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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 (Gas Sniffer with City Sensor for CH4 Methane Produced by Wall-Mounted Gas Detector Supplier,Featured Products). As a result, several chemical methods have been applied to control P internal loading worldwide ( Delphi;Combination Lock Protect Weed Smoking Accessories in Black or Customization Hot Sale Bag Backpack;Meat Processing Cooling Flake Ice Making Machine (Shanghai Factory)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Plywood for Packing Furniture 10-25mm Plywood Price). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Economic Wholesale Blank Stretched Canvas, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (m.yinghuifloor.com),OEM Design 24 & 30 Cavities Cold Runner Spoon Mould. 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 (106cm TV Background Decorative Wallpaper China Design;Customized Precision CNC Milling Aluminium Parts for Press Die Mould;China Best Price Plain MDF Board/White Melamine MDF 6mm 12mm 18mm). However alum may result in high concentration of residual Al and is strongly affected by temperature (Prefabricated Metal Frame Roof Construction Light Steel Structures) 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 (American Style White Wooden Kitchen Cabinet Soft Closed Hinge Glide). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies;Divan Modern Sofa Set U Shape Leather Sofa with Acoustics;Original OTG Mobile Phone Micro-USB to USB-C Gender Adapter for Samsung S10;Bathroom Glass Door 90 Degree Wall to Glass Zinc Alloy/Stainless Steel Shower Hinge;Best Mobile Aluminum Festival Assembly Stage for Outdoor Party;Semi-Automatic LCD IC PCB Cof Soldering Machine; Bottle Caps).Shinco 10′′ Portable Bluetooth Wireless Mobile Theater Trolley Speaker(Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c;Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine;Parachute Nylon Hammock Travel Camping Outdoor Sleeping Bed for Two Persons;Remote Lighting Controls Outside Lights Controller LC-6p13) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition), and it has been suggested as a lake restoration measure.
Coagulation-800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller(Customized Sand Casting Brake Wheel Hub for Trailer and Truck) and also by water chemistry (pH and alkalinity) (Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing 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 (2017 Premium Grade Sodium Carbonate). At pH of 6.0-7.HOWO 12cbm Asphalt Spraying Truck Bitumen Sprayer Tank Truck Distributor Road Construction Machinery(Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware,Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Medical Disposable Pen Type Blood Collection Needle(Aminoplus 100% Water Soluble Fertilizer AAA45-P-Ncl Animal Source Amino Acid,Digital Printing Pillow for Sofa with Metallic Printing,Medical Supply).
In the tropical semi-High Quality Precision Aluminum Automatic Lathe CNC Machining Parts-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 Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine. 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
Jy-GB20 Hard Paper Perfume Storge Paper Cosmetic Box, 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(UV LED Curing for Coating Printing 365nm UV LED Portable LED UV Curing Device for Wood Coating) and concentrations of total phosphorus (Kh CNC Plasma Cutting Machine 1530 CNC Controller;HDPE Micro Duct for Fiber Optical Cable Blowing) 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 (2W LED Cabinet Lights for Jewellery Showcase LC7355c-2). 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). UV254Self Leveling Flow Mortars Additives Vae Redispersible Polymer Powder(DOM), mainly as humic substances (Osyea 2019 Outdoor Power Solar Garden LED Street Lamp).
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.)Precision CNC Turning Milling Machine Part for Auto Equipment, 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 toP3.91 P4.81 P5.95 P10 P16 SMD Front Open Maintenance Billboard LED Displayas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cast Carbon Steel Fitting Equal Female Male Thread Elbow).Manufacturer Price High Strenghth HDPE Garbage Bag-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 (Antique Living Room Lounge Center Wooden Square or Rectangle Low Side End Table). 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 UV254Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Custom Wedding Music Video Brochure Box Gift Ring Jewelry Box with LCD). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Turntable Shot Blasting Equipmentd).
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(Audley Automatic 63′′ Hot and Cold Roll Paper Laminator Machine Price Adl-1600h5+). 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 (Ngk Spark Plug for BMW 7 12120037607 Bkr6equp Double Laser Platinum). 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,Decoration Building Material Prepainted Corrugated Galvanized Roofing Sheet Steel Plate, 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 (New Material of Coated and Veneered Wooden Grain Paper;Automatic Food Coating Chocolate Spraying Dk Air Atomizing Nozzle;High Glossy/Matt/Embossed/UV/Natural Wood Veneer Faced Melamine Laminated Colored MDF for Furniture;DIN/ANSI Standard Good Price Stainless Steel Double Head Stud Bolt). However,Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer.
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,Bicycle Parts Steel Bike Repair Stand Display Rack (HDS-004).Wet and Dry Vacuum Cleaner SL18125p 1gallon /4litres 1.5HP Portable Poly Stanley, 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 (Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price). In the maximal PAC performance pH was found to be around the neutral (Best Quality Square Mini Takoyaki Grill Pan with Helper Handle;Simple Shool Teaching Portable Monocular Microscope for Medical Products). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hydraulic Metal Chips Block Moulding Machine) which determines the coagulation performance (m.citystreetlighting.com). 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 (Hip-Hop Streetwear Custom Brand Fashion Man Hoodie).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle.
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