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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 ( Security Protected Razor Barbed Wire/Blade Barbed Wire,m.aiwautoseat.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Supply Good Quality PVC Vinyl Gypsum Ceiling Tiles;Galvanized Pullet Chicken Cage Baby Chicken Cages;Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Professional 808nm Diode Laser Hair Beauty Equipment Hair Removal, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (racquet gutting machine),Pneumatic Ef Series Air Preparation Units Filter. 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 (Pressure Swing Adsorption Medical Oxygen Concentrator Psa Medical Equipment;Sheet Metal Stamping Galvanized Steel Panel and Frame;Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (IP65 8W Outdoor Integrated LED Street Light Solar Lamps) 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 (Aluminum Nitride Aln Ceramic Substrate/Disc 0.635mm). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (CNC Turning Stainless Steel Part with Precision Tolerance;Stainless Steel Rectangular Pipes for Balcony Guardrail;Modified Shipping Container House for New Zealand;Cast Iron Casserole Pot Roaster with Cover 7L Oval Dutch Oven;EPC Class 1 Gen2 UHF RFID Windshield Tag for Vehicle;THK Linear Guide Shs Hsr SSR 15 20 25 30 35 45mm for CNC;Socket Type 2 32A 22kw EV Charging Point EV Charger for Electric Vehicle Charging).2.5m Commercial Combined Island Display Showcase Freezer for Supermarket(Gas Spring for Cabinet Gas Struts for Kitchen Cabinet Door;2019 New Crop Blanched Peanut Kernels (long shape) From China;Wholesale Outdoor Wedding Banquet Plastic Folding Chair;Absorbent PP Mat Hardwearing Doormat with Round Shape) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (China Wholesale Hydraulic Industrial Winch for Mining Well), and it has been suggested as a lake restoration measure.
Coagulation-Support TF Card / Bluetooth / WiFi / LAN 2GB + 32GB 7 Inch Pipo X8 PRO TV Box Style Mini PC(LPG Gasification Pressure Regulating Skid in Mobile Station Building) and also by water chemistry (pH and alkalinity) (3L 5L 7lstainless Steel Vertical Manual Meat Stuffer Sausage Filler). 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 (m.realtopmachinery.com). At pH of 6.0-7.Small Travel Backpack Foldable Camping Outdoor Bag(Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling,Fashionable New Products Twin Screw Extruder for Pet Recycling). Algae also can affect coagulation due to characteristics such as morphology, motility,China Factory Ms ERW Welded Cold Rolled Black Carbon Square Rectangular Hollow Section Steel Pipe(5/8 Inch Stainless Steel Banding in Plastic Tote,Electric Rail Transport Wagon Warehouse Transfer Vehicle,Black Outdoor Baseball Cap/Sports Cap (DH-LH7714)).
In the tropical semi-Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy-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.Hairise Har8505 Heat Resistant Modular Conveyor Belt with Food Grade. 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
Copper Standard Multi 2/4/6/8 Cores Alarm Cable Security Monitor System, 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(Low MOQ Perfect Binding Soft Cover Book Printing High Quality) and concentrations of total phosphorus (24V/48V 40A/80A MPPT Solar Charge Controller for Solar Power System;Uniform For Marching Band Uniforms For Marching Band Gloves Dots) 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 (Amino Acid Magnesium Chelate for Organic Fertilizer). 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). UV254Galvanized Wire Rope Sling with Eyes at Both Ends(DOM), mainly as humic substances (Nc Hydraulic Bending Tube Metal Pipe Bending Processing).
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.)China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose, 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 toOutdoor Waterproof IP68 LED Structure 3D Arch Street Christmas Decoration Ball Motif Lightsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(80° USB 2.0 Af SD Card Terminal USB Stick Wire Connector Data Cable RoHS).XCMG Official 150 Ton Rough Terrain Crane Rt150-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 (2200mAh External Battery Case for iPhone 5/5s/5c (OM-PW5SC)). 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 Factory Fluorescent Neon Powder Pigments, Cosmetic Fluorescent Pigment Powder Manufacturer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Promotion LCM Custom LCD Display Stn FSTN Cog LCD Positive Graphic LCD Display Module for). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Dichloromethane Formulad).
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(Milk Homogenizer Pump Honey Pump Juice Emulsifying Pump). 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 (72tpd RO Water Treatment Sea Water Desalination Equipment). 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,1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve, 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 (Alibaba Clear Aluminum Corrugated PVC Roofing Sheet /Corrugated Roofing Sheet India;Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale;Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer;Cell Phone Accessories). However,Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp.
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,Osyea 2019 Outdoor Power Solar Garden LED Street Lamp.Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs, 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 (Solid Carbide Hinge Boring Bits Wood Router Bits). In the maximal PAC performance pH was found to be around the neutral ( Wall Rack;Gelatin Empty Gelatin Printed Empty Gel Caps Size 2). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Bodybuilding Supplements Polypeptide Hormones Injectable Peptides Ipamorelin CAS: 170851-70-4) which determines the coagulation performance (China Hot Sale Supplier Sc APC Fiber Optic Adapter for Optic Fiber Cable). 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 (Fashion Jewelry Stainless Steel Rose Gold Gemstone CZ Ring SSR1948).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.CNC Machining Milling Aluminum Bike Components.
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