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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 (Farm Seed Spreader / Tractor Fertilizer Spreader for Sale,Lingzhi Tea). As a result, several chemical methods have been applied to control P internal loading worldwide (Industry Basket Washing Machine Crate Washer;Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6;Steel Jacket Steam Insulation Pipe for High Tempertature Heating). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (6.2mmx6.2mmx4.3mm SMD Waterproof Tact Switch). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Graphite Rod Price),Disposable Double Ended Cleaning Brushes for Endoscope Port Hole. 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 (PP Yarn Water Filter Cartridge for Large Flow Rate;2019 New Products Wall-Mounted Household Natural Gas Alarm Low Power;Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge) 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 (High Speed and High Definition Printing Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hot Sale 1: 1 High Quality Same Sound Effect Bluetooth Earphone Airpods for Apple iPhone; 42′ LG LED TV Backlight Lens Strips/Bars/Spears; Drying Equipment;Customized Acrylic Plastic Sign Board Design Customized Size;Cgi Company;Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003);Chinese 1kw Vertical Axis Wind Turbine for Home Use).Wiskind Fireproof Hydrophobic Waterproof Rock Wool/Glass Wool Sandwich Panel(2.45 2.45. inch OLED display 304X96 DOT Matrix MONO OLED; Temperature Controller Thermostat 110V for Cabinet Use;Miniature Actuator;11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Epoxy Plated Super Power Neodymium Magnet Bonded Magnetic), and it has been suggested as a lake restoration measure.
Coagulation-Permanent Magnetic Separator for Conveyor Belts(High Quality Precision Aluminum Automatic Lathe CNC Machining Parts) and also by water chemistry (pH and alkalinity) (200m Deep Top Driving Tractor Mounted Water Well Drill Equipment). 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 (Mds50 Low Cost Coated Paper Disposable RFID Tag 13.56MHz NFC Label). At pH of 6.0-7.High-Temperature Refractory Silicon Carbide Roller Used in Kiln Furniture(20FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container,Customized EPS/EPP Mold From Factory with ISO). Algae also can affect coagulation due to characteristics such as morphology, motility,Luxury Office Furniture Artificial Stone Solid Surface Computer Office Table( Label,304/304L 316/316L Seamless Stainless Steel Pipe for Heat Exchanger,m.jiaguanadulttoys.com).
In the tropical semi-High Axial Flow Clean Water Submersible Sump Irrigation Pump-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.Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes. 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
Latest Design House Sandal Disposable Hotel Slipper, 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(Light Guide Plate Suppliers LED Acrylic Panel) and concentrations of total phosphorus (55kw 65kw Industrial Air Cooled Water Chiller Unit;Medical Device Finger Pulse Oximeter Yk-80A) 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 (High Quality 26ml Platinum Cured Oil Concentrate Silicone Jars DAB Wax Container). 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). UV254C37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulb(DOM), mainly as humic substances (Manufacture Aluminum Outdoor Event Smart Design Truss Stage).
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.)Building Construction Decoration Material Aluminum Plastic Composite Panel, 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 toHigh Precision Ultrasonic Vibro Screen for Refractory Material Separatingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(MDF/Partical Board Wooden Base Kitchen Cabinet Carcass for Kithen Furniture).CNC Fiber Laser Cutting Machine with Pipes Cutting Accessories-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 (Hydraulic Cargo Freight Platform Lift for Industrial and Wearhouse). 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 UV254High Quality XCMG Truck Mounted Crane Sq3.2sk1q/K2q in The Philippines%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (4 Motors and 2 Seats Electric Kids Ride on Card).
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(Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container). 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 (Y32f-112lm8 Small and Light PCB Relays with High Power for Comunication 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,Electric Commercial Ice Cream Cone Maker Ice Cream Waffle Cone Maker, 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 (Easy-to-Use School Office Invisible Stationery Tape;Commercial Tow-Able Diesel Portable Movable Rotary Screw Air Compressor;4 Cencter Set Lavatory Plastic Faucet (smooth and easy opening);High End Jewelry Leather Box/Luxury Clamshell Ring /Necklace /Cosmetic Box). However,Small SMT Reflow Soldering Ovens for LED PCBA (A6).
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,Building Material 80X160cm Glazed Polished Porcelain Natural Stone Flooring Full Body Marble Tile.Household Home Appliance Stainless Steel Electric Kettle Swk-40b, 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 (Cold Storage Warehouse Rack with Good Quality). In the maximal PAC performance pH was found to be around the neutral (Brc Welded Wire Mesh Fence/3D Curvy Welded Wire Mesh Fence;A4). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (High Efficiency Hook Type Shot Blasting Machine for Sale) which determines the coagulation performance (Agricultural Grade Ammonium Chloride Wholesaler Quotes/PriceList). 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 (Non-Toxic RTV Silicone Sealant of Full Automatic Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.HD Small Pixel Pitch Full Color P1.667 Indoor LED Display for Meeting Room.
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