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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 (Solar Powered Pelican Light LED Decoration Bird Garden Ornament Outdoor Lighting,Surface Grinding Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter;Hot Sale Handheld Lcr Meter with Signal Level 0.6vrms (AT825);Fully Automatic Kid Ride on Toy Car / Rechargeable Baby Car). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Smelting Furnace Dust Collector Fiberglass Bag Filter). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ride on Concrete Power Trowel Machine with Suitable Seat, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Bag unloader),Concrete Grinding Plate for Abrasive Machines of Abrasive Disc. 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 (China G603/G439/G602/G655/G664/G654/Juparana Granite Stone Vanity Top Kitchen Countertop;Electronic Smoke Digitizer Quartz Atomizer Short Quartz Tube;Sell High Quality Food Grade Sodium Carboxymethyl Cellulose CMC). However alum may result in high concentration of residual Al and is strongly affected by temperature (European VDE Schuko 3-Pin Waterproof IP44 Power Plug) 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 (Blank White Plastic Contact Chip Card Wholesaler Quotes & PriceList). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale OEM/ODM Sexy V-Neck Backless Cross Women Evening Prom Dress;Professional Fabrication Metal Sheet Mechanical Stamping Machine Parts;Professional Double Cup Fully Automatic Coffee Machine;Waterproof Straight Male Female Sensor Connector;Supplier in China Supply CAS: 56-40-6 Amino Acid Glycine with Good Price;Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush;Custom ID Card Holder Soft PVC Plastic Transparent Horizontal and Verticalbusiness Card Holder (14)).Duplex Parallel Connection Bag Filter for Filtering Drinking Mineral Water(Mill Finish Aluminum Coil Sheet 5052 5005 5754 5083 Price From China Factory;Custom Hardware Lathe Turning Steel Metal Parts High Precision CNC Machinery/Machined/Machining;www.citystreetlighting.com;Jomo Lite 40 Vape Pod Build-in-2000mAh Battery Box Mod Amazon Best Buy) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material), and it has been suggested as a lake restoration measure.
Coagulation-China New Design TPU/PVC Layflat Flexible 6 Light Duty Suction Hose(Yh Water Jet Cutting Machine Spare Parts Waterjet Nozzle) and also by water chemistry (pH and alkalinity) (White Chemical Coating Powder for Fast Dry Sublimation Paper). 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 (China Resin Gold Dice). At pH of 6.0-7.2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top(Trenchless Directional Tricone Drill HDD Reamer,AISI 304 316L 309S 317L 321 904L 421 Stainless Steel Strip). Algae also can affect coagulation due to characteristics such as morphology, motility,Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060)(Nyp Rotor Type Oil Pump High Viscosity Internal Gear,BPW Spring Mechanical Steel Oil Fuel Diesel Tank Semi Trailer for Sale,Plasma Torch/Gun).
In the tropical semi-Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror-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.7 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System. 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
Monofilament Fishing Tackle Green Nylon Fish Net, 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(OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat) and concentrations of total phosphorus (Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085);Auto Tracking Smart Ai Security Camera) 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 (1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron Pipe). 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). UV254IP65 Waterproof Metal Distribution Box and Power Metal Box(DOM), mainly as humic substances (Quick Charger 18W USB-C Pd Charger for iPhone11).
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.)Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525, 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 LED Courtyard Solar Street Lights for Garden Path Roadas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(E Assist Bike).Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling-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 (3/2 Way 3h210 Airtac Hand Control Manual Pneumatic Air Valves). 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 UV254New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (1.2mm/1.6mm Stainless Steel SS 304 Wire for Thermal Spray Wire). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China High Quality Synchronous Belt Pulleyd).
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(OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag). 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 (Automatic Control Apricot Shell Charcoal Carbonization Kiln Price). 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,Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt, 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 (Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove;750ml Round Shape Beer Wine Liquor Glass Bottle High Quality;M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher;www.billowtimewatch.com). However,Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector.
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,Yidek Electric Energy Supply Quality Intelligent Analysis Meter with Ce.Tractor Trailer Cable Truck 7 Core Spiral Coiled Electric Cable for Tractor & Trailer, 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 (6 Head Garment Computerized Embroidery Machine Industrial Use for Sale). In the maximal PAC performance pH was found to be around the neutral (Carnival Rides Samba Balloon Race Happy Swing Jellyfish for Sale;4-Way Brass Angle Valves Chrome Plated Water Supply Stop). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hardware Tools 1.2mm Thickness Wire Pole Pipe Clip Tube Clamps) which determines the coagulation performance (Aaaaa-Rydmet Cemented Tungsten Carbide Bur Blanks-Bsa). 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 (Hcd600 RF Wireless Remote Control Duplicator Machine for Locksmith).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Precise Process Custom Metal Works Services Sheet Metal Fabrication.
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