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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 (5 Inch Diamond Protected Teeth Blades for Cutting Granite,Natural Wood Slicer Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt;Steel Structure Roofs System TPO Waterproof Membranes;Water Heater Single Head Shrinking Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Co-Extrusion Extruder Single Screw Auxiliary). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Denso Nozzle G3s32 for 295050-056#1465A351 Common Rail Injector System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Diesel Generator 1 Phase),Wholesale Custom Logo Printed Chocolate Candy Box. 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 (2019 Unique Design UV Printing Phone Case for Apple iPhone 8;Immersion Gold 94V0 Circuit Board Assembly Saving Energy Electrical PCB;Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker). However alum may result in high concentration of residual Al and is strongly affected by temperature (OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer) 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 (Chili Sauce Packaging Filling Back Seal Bag Packing Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Sun Cover Heat Resistance Shade Privacy Screen;Clear Plastic PVC Window Cmky Full Color Printing Box;Good Quality Brow Pencil Pencil Private Label Wholesale;Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic;Silicone Babies Teething Toy for Mon Jewelry;Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow;Jingsun off Grid 100kw Solar Power System for Project).Custom Wedding Music Video Brochure Box Gift Ring Jewelry Box with LCD(RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp;Very Cute Baby Gift Packing Shopping Carrier Paper Bag;Socket Welding High Diameter Flange Forged Steel Valve Flange; Cookware Set with Hammer Pattern) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Mimaki Jv5/Jv33/Jv300/Ss21/Sb53 Permanent Ink Cartridge Chips), and it has been suggested as a lake restoration measure.
Coagulation-Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring(Solid Surface Stone Table Top Restaurant Black Round Dining Tables) and also by water chemistry (pH and alkalinity) (Custom Printed Plastic Soft Vinyl PE Ziplock Packaging Bag). 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 (New Io Hawks & Monorover R2 Electric Unicycle Mini Scooter Two Wheels Self Balancing Scooter). At pH of 6.0-7.LED Car Work Light of 51W 6inch with off-Road Spot Beam(Balcony Terrace Roof Canopy with Aluminum Frame,Coolsour Air-Conditioning Compressor Crankcase Silicone Rubber Heating Strip). Algae also can affect coagulation due to characteristics such as morphology, motility,Long Using Time Rechargeable Cordless Hair Clipper(Chain Rigging Clip U Bolt Saddle Cable Clamp, High Temperature Boiler Steel Pipe Tube ASME SA335 P22 P 91,Nylon Open-End Zipper Making Machine).
In the tropical semi-Water Oil Liquid Level Measurement Devices Glass Level Gauge-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.Manufacturer Black Painting Seamless Carbon Steel Tube Hose Pipe. 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
Small Electric Winch New Product 220V Mini Electric Winch, 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(Surface Paiting Line UV PU Water Base Spraying Robot Arm) and concentrations of total phosphorus (Food Grade Heat Preservation Lunch Box/Heat Preservation Case/Heat Retaining Box;Sdec Marine Gensets) 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 (The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture). 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). UV254Custom Clear Acrylic Chinese Tea Table (BTR-Q1012)(DOM), mainly as humic substances (DIN7504 Stainless Steel Self Drilling Drywall Screw).
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.)Ngk Spark Plug for BMW 7 12120037607 Bkr6equp Double Laser Platinum, 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 toCircular Magnetic Lifter for Steel Scrap Lifting MW5 - 70L/1as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(How Much Is Installing 10 Kilowatts of Photovoltaic Power?).Vending Machine 12.1 Inch Embedded or Open Frame Capacitive Touch Screen Monitor-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 (Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor). 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 UV254Small Portable Hand Cotton Picking Machine in India China Picking Cotton Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Patient Modular Monitor with Wireless Network and Wire Network). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (10 Inch (273mm) Steel Wire Wrapped Water Well Pipe with Stc Threadd).
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(Medical Infusion Pump for Human and Veterinary with Fluid Warmer). 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 (Ce Certificated Acm-60 PTFE Powder Grinding Mill). 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,Online Hot Sale 5 Tier Silver Home Organizer Shelving, 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 (Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall);Auto Crane Electrical Overhead Cable with Steel Wire;Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801;Desk Lamp High Quality Suppliers/Manufacturers for Sale). However,Genuine Car Spare Auto Parts 48531-80581 for Shock Absorber.
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,Replacement EPE Eppensteiner Filter Element (8260P10S000P).Women′s Foam White Lettering-Print Cotton T-Shirt, 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 (Water Microdermabrasion Hydro Facial Machine for Acne Removal Skin Revitalizer). In the maximal PAC performance pH was found to be around the neutral (Reflecting Aluminum Film Vacuum Evaporation Coating Equipment;5mm Wall Mounted Hotel LED Lighted Bathroom Mirror). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Wholesale Compression Mesh Women Fitness High Waisted Seamless Leggings) which determines the coagulation performance (Butterfly Valve with Wafer Pneumatic Actuator Output Torque). 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 (China Products/Suppliers. China Wholesale Crystal Liquor Bottle with Frosting and Decal).
Long Range Passive EPC Gen2 Monza Chip UHF RFID Wet Inlay, charge and density, factors that influence directly in flock sedimentation.Factory Direct Sale Hotfix Laser Motif Customer Desgined for Decoration(Airstream Mobile Food Truck Trailer/ BBQ Food Caravan/ Beverage Cart;Die Casting Injection Molding Parts Deburring Deflashing Vibratory Barreling Machine). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Foil Induction Sealing Machine for Glass Plastic Bottle Jar). Extracellular and surface-Rubber Wheel Stopper Car Parking Blocks Rubber Speed Cushion(Cardboard Box Printing Die Cutting Laser Machine,Popular Colorful Fiberglass Roof Tile / Bitumen Shingles Building Materials). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (3D Silver Reflective Custom Heat Transfer Label Garment Label), which can be one important cause of the increase in coagulant demand in algae-rich waters (Warm Leather Glove Mink Fur Glove/Leather Palm Rabbit Fur Glove).Hot Sale 99% Powder Form CAS 70288-86-7 Ivermectin with Best Price(England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification), particularly humic susbtances. Humic substances are highly negatively charged (2018-2019 F150 Raptor Style Front Bumper Fits F-150), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Lash Camellia Ellipse Flat Eyelash Extension Makeup Tool Lashes Extensions 102). Maximal UV254removal was observed to be found around pH 6.0 (Best Face Injektions Hyaluron Hyaluronic Acid Dermal Fillers Cheek Fillers). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Factory Price BV Designer Handbag Genuine Leather Women Purses Real Leather Ladies Handbags).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Prefabricated Structural Steel Warehouse Steel Structure Frame Building Structure.
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