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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 (Modular LED Lamps LED Flood Light 50W-500W Replace Indicator Lamps Hidden 2000W,Reci 100W 150W CO2 Laser Cutting and Engraving Machine for Wood). As a result, several chemical methods have been applied to control P internal loading worldwide (Good Cleaner Cotton Rope Mop Wood Mop Stick;Customized Cast Iron Ak41 Type V-Belt Pulley for 4L;Red Enamel Cast Iron Fondue Pot with Forks). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Automatic White Cardboard Paper Roll to Sheet Cutting Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hydraulic Metal Chips Block Moulding Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (PVDF Curtain Wall Cladding Perforated Aluminum Railing for Building Facade),Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine. 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 (Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory;3mm Poplar Plywood with Fancy Veneer Directly;Farm Seed Spreader / Tractor Fertilizer Spreader for Sale). However alum may result in high concentration of residual Al and is strongly affected by temperature (Industry Basket Washing Machine Crate Washer) 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 (Fisheye Hidden Camera). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6;Steel Jacket Steam Insulation Pipe for High Tempertature Heating;6.2mmx6.2mmx4.3mm SMD Waterproof Tact Switch;PP Yarn Water Filter Cartridge for Large Flow Rate;Well Point System;2019 New Products Wall-Mounted Household Natural Gas Alarm Low Power;Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould).Natural Light Green/Beige/Pink Slate Thin Cut Surface Culture Stone(High Density White Magic Sponge Magic Eraser Melamine Foam Cleaning Sponge Car Cleaning Sponge;Hot Sale 1: 1 High Quality Same Sound Effect Bluetooth Earphone Airpods for Apple iPhone;China Make A Makeup Mirror With Lights; 42′ LG LED TV Backlight Lens Strips/Bars/Spears) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Drying Equipment), and it has been suggested as a lake restoration measure.
Coagulation-S23 Electric Logistic Car, Cargo Box, Cargo Van, Cargo Container, Cargo Pickup, Closed Logistics Vehicle(Customized Acrylic Plastic Sign Board Design Customized Size) and also by water chemistry (pH and alkalinity) (Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003)). 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 (Cummins 6CT Engine Oil Cooler Core 3974815 3918175 3918174 3914308). At pH of 6.0-7.Na2co3 Soda Ash Sodium Carbonate Food Grade(Chinese 1kw Vertical Axis Wind Turbine for Home Use,2.45 2.45. inch OLED display 304X96 DOT Matrix MONO OLED). Algae also can affect coagulation due to characteristics such as morphology, motility,Water Jet Cutting Machine Spare Parts Waterjet 3/8 High Pressure Pipe( Temperature Controller Thermostat 110V for Cabinet Use,11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer,China Economic Customized Design Steel Frame Farm Buildings Poultry Farm House for Chicken).
In the tropical semi-Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil-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.Three-Way Car Horn Air Compressor 12V 24V. 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 Electric Heating Mixing Kettle for Food Industry, 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(200m Deep Top Driving Tractor Mounted Water Well Drill Equipment) and concentrations of total phosphorus (20FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container;Breathe Easy Humidifier) 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 (304/304L 316/316L Seamless Stainless Steel Pipe for Heat Exchanger). 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). UV254China Supplier Customized Pressing Stamping Parts(DOM), mainly as humic substances (Wooden Grain Siding Plank for Villa Integrated House).
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.)Custom-Made Optical Glass Bk7 K9 Doublet Achromatic Lens, 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 toWired/Wireless Smoke Detector for Fire Alarm Home Alarm Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Seal Strip with Wool Pile Brush Wether Strip for Shower Glass Door).Galvanized Steel Spiral Duct for Ventilation Ducting-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 (Manufacture Aluminum Outdoor Event Smart Design Truss Stage). 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 Standard Cum B3.3 Water Temperature Sensor for Excavator%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Rubber Wheel Stopper Car Parking Blocks Rubber Speed Cushion). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (12 Inch Core Drill Bitd).
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(Nylon Watch Bands with Metal Buckle 20mm Strap). 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 (High Precision Ultrasonic Vibro Screen for Refractory Material Separating). 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,Kw-700 Industrial Commerical Driving Type Floor Scrubber Price, 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 (Hydraulic Cargo Freight Platform Lift for Industrial and Wearhouse;Kiet Brand High Efficiency Automatic Hydraulic Cam Dismounting Puller;Dog Cat Car Products Travel Accessories Seat Pet Carrier Bag;Ppgi Steel Coil). However,Ribbed Colorful Wall Plug Anchor with Screw.
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,Plastic Fork Mould for Cake Disposable Tableware Injection Molding.28dBi 1575.42MHz BNC Connector Active GPS Antenna, 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 (Food Lunch Box 4 Compartment Aluminium Storage Box Disposable Aluminum Foil Container). In the maximal PAC performance pH was found to be around the neutral (Y32f-112lm8 Small and Light PCB Relays with High Power for Comunication Equipment; Door Mat). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Made in China Multi-Storey Steel Structure with Light Steel Frame) which determines the coagulation performance (Hand Woven Stainless Steel Wire Rope Cable Zoo Mesh Animal Enclosure). 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 (Easy-to-Use School Office Invisible Stationery Tape).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Disc Neodymium N35 N45 N40 N42 N38 N48 N52, Wholesale Magnet, Magnets in Ningbo.
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