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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 (Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board,Vitrified Diamond CBN Grinding Wheel for Auto Steering Pump Gear Box Bearing Od 534mm-1200mm). As a result, several chemical methods have been applied to control P internal loading worldwide (P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen;Automatic High Speed Welding Manipulator Machine;Stainless Steel Juice Multi-Bag Filter Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (China Manufacturer Mifares50 13.56MHz RFID Thin Smart Card). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (ASTM 304 304L 316 316L Stainless Steel Sheet / Plate for Ship Building),Best Quality PCB Design and Production Manufacturer Consumer Electronics PCBA Boards. 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 (2000bph Chicken Slaughtering Equipment Line;400g Aquaria Ozone Generator for Aquarium Fish Farming Water Treatment;Portable Far Infrared Sauna Dome with Tourmaline Stone). However alum may result in high concentration of residual Al and is strongly affected by temperature (30W PA System Surround Sound in Ceiling Mount Speaker Waterproof Speaker) 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 (Plug Power Cable Cord 3-Pin SAA Electrical PVC Power Cable 10A Plug). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant;PCB Masking High Temperature Resistant Tape Polyimide Film Tape; Mild Steel;2019 New Factory Direct Metal Bird Feeder for Garden Decoration;Electrical Oven Switch; E-Liquid;Breathable High Visibility Reflective Safety Leisure T-Shirt).Plastic Nozzle 360 Rotary Kitchen Faucet Shower Head Economizer(Hot Sale Magnetic Strip Inserting Making Machine;Denso Nozzle G3s32 for 295050-056#1465A351 Common Rail Injector System;Disc Type Glass Insulator Lxp-100 Anti-Fog/ Anti-Pollution;High Quality Portable Deep Well Solar Pump Solar Water System) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Detergent Camellia Seed Extract Tea Saponin 60%-98%), and it has been suggested as a lake restoration measure.
Coagulation-Ruizhou Auto Feeding Laser Fabric Cutting Machine / Textile Cloth Laser Cutter( Made in China) and also by water chemistry (pH and alkalinity) (Ce Factory Sale Waste Logs Drum Wood Chipper). 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 (Automatic Gyroscopic Ink Mixer for High Drum (JY-30A2)). At pH of 6.0-7.High Cargo Side Electric Cargo Food Adult Recumbent Micro E- Motorcycle Tricycle Trike /E Loader(Jy-GB20 Hard Paper Perfume Storge Paper Cosmetic Box,Custom M12 4 7 8 Pin to RJ45 Connector Cable Assembly). Algae also can affect coagulation due to characteristics such as morphology, motility,17inches Travel Computer Backpack Bag Water Resistant Business Laptop Backpack(3 in 1 Flat Noodles Data Transfer Charger Cable for Android/Ios,New Design IP65 100W LED Flood Light for Sports Lighting,Combination Carabiner Lock).
In the tropical semi-CNC Fiber Laser Cutting Machine Cutting Stainless Steel, Mild Steel,-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.Hot Selling Product Overlock Portable Mini Handheld Household Sewing Machine Fhsm-700. 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
Stainless steel glass/Bathroom/Shower push Door Knob/Handle glass hardware GH-306C, 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(Magnetic Badge Holder Rectangle Magnet Button Badge Maker) and concentrations of total phosphorus (Wholesale Wooden Inlay Shell Custom Boutique Comb;1kw Solar Hybrid Inverter Supplier) 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 (Stainless Steel Handrail Long Bar Holders for 12mm 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). UV254Water Play Equipment Inflatable Gym Air Track Mat(DOM), mainly as humic substances (Atc Wood CNC Router Linear Type Woodworking Machine with Auto Tool Changer Sign 1325/1530/2030).
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.)Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine, 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 toCheap Ghost Clear Transparent Acrylic Napoleon Chair for Weddingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Coated Stainless Steel Ladder Multi Hooks Cable Tie).Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes-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 (Cross Belt Magnetic Separator Super Strong Neodymium Permanent Magnet to Remove Iron Scrap). 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 UV254Gear Operated Cast Iron Wafer Type Butterfly Valve%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (PCB Reverse Engineering SMT PCBA Factory WiFi Router PCB Assembly). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Sc Sc Duplex Sm Metal Style Fiber Optic Adapterd).
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(Shengrun Utility Bulk Cement Fly Ash Flour Transport Tanker Truck Trailer). 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 (Pn10). 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,Weather Resistant Outdoor Rattan Wicker Aluminum Folding Reclining Beach Chair, 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 ( Drainage Pipe Machine;15.6 Inch LED Backlight Wide Screen HD LED TV Ce CB; Debossed Hotel Towel;W Series Spring Full Bore Type Steam Air Gas Pressure Safety Valve). However,Cabinet Light Motion LED Activated Bed Light 5V PIR Motion Sensor LED Strip 2835.
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,Front Maintenance Outdoor Full Color P8 LED Display (P8 LED Video wall).Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container, 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 (Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine). In the maximal PAC performance pH was found to be around the neutral (Tamper Evident Walmart Office Depot White out Warning Void Self-Adhesive Security Tape for Bottle;American Type Earth Clamp for Welding Equipment). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Woodworking Edition - Waxed Canvas Tool Bag - Padded Straps) which determines the coagulation performance (Commercial Use Heavy Duty Cube Ice Maker Ice Machine). 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 (2017 New Material Fashion Luggage Good Suitcase).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.1.0L Chinese Steam Cooking Type Electric Tea Kettle with Pot.
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