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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 (Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen,78mm). As a result, several chemical methods have been applied to control P internal loading worldwide (172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172);4 Drawer Steel Office Vertical Filing Cabinet;Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (CO2 Gas Shielded Stainless Steel Welding Wire (ER308L)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Popular Water Tricycle Bike),Wall Mounted Bathroom Tissue Holder Toilet Paper Towel Roll Holder. 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 (Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner;Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden;Plastic Round Home Storage Box Vacuum Insulated Lunch Box). However alum may result in high concentration of residual Al and is strongly affected by temperature (Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting) 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 (Steel Hydraulic Tubing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge;High Precision Customized Medical Injection Mold for Needle Holder;Customized Mining Equipment with Drawing Design; Motor Cable Wire Electrical Power Cable;Pmma Blocks For Cerec;Class 1 Foam Rubber Insulation Pipe for Air Conditioner;Sublimation Coated Aluminum Sheets for Heat Transfer Printing).Ride on Concrete Power Trowel Machine with Suitable Seat(Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top;Ccaf Vertical Cartridge Dust Collection for Sand Blasting;Garlic Harvesting Machine; Camping) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine), and it has been suggested as a lake restoration measure.
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In the tropical semi-2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top-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.Laminated Glass Auto Clave with TPC/PLC System (SN-BGF3060). 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
Modern Design Oval LED Lighted Beveled Edge Wall Fogless Bathroom Mirror, 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(Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging) and concentrations of total phosphorus (2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank;Custom Printed 3D Sports Team Club Logo Flocking Heat Transfer Patches for Jackets) 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 (Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36). 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). UV2547 Inch Wired Color Villa Video Door Phone with Coms Camera V7c-P1 Intercom System(DOM), mainly as humic substances (Genuine 1m USB Date Charging Cable for iPhone).
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.)Monofilament Fishing Tackle Green Nylon Fish Net, 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 to2019 Wholesale 6.5HP 300kgs Mini Dumper Crawler for Agricultureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Pen Mold Components).IP65 Waterproof Metal Distribution Box and Power Metal Box-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 (Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels). 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 UV254Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Steel Fabrication Part Custom Steel Sheet Metal Fabrication Work). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Injection Molding Machine Make in China Best Priced).
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(M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports). 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 (Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm). 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,Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling, 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 (Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer;Online pH TDS Ec Controller Digital Electrical Conductivity Meter;Rechargeable Battery Powered Indoor WiFi Camera with Custom APP;Second Hand Scrap Foam and Scrap Rubber Glue). However,New Designer PU Fashion Ladies Backpacks Handbags for Brand Holder and Wholesale.
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,Cal117 (TB117) Flame Retardant Fire Barrier Batting Felt.Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector, 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 (Yhzs50 Mobile Concrete Mixing/Batching Plant with Low Price). In the maximal PAC performance pH was found to be around the neutral ( Wood Peeling Lathe;2019 New Arrival Original Adaptive Fast Adapter Rapid Wall Charger for Samsung S10). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Luxury Office Furniture Artificial Stone Solid Surface Computer Office Table) which determines the coagulation performance (Industry Control PCBA for SMT Wave Soldering Process). 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 (7inch TFT LCD Display Module for Car Compass with resolution 1024(RGB)*600).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.2.5liters F-Style Metal Steel Tin Can_Packaging Container.
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