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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 (Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top,Granular Anthracite Coal Filter Media Price for Water Purification). As a result, several chemical methods have been applied to control P internal loading worldwide (Ccaf Vertical Cartridge Dust Collection for Sand Blasting; Camping;GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hot Selling Low Price Wet Type Drum Permanent Magnetic Separator Made in China),Car Cooling Spare Parts Compressor Magnetic Clutch. 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 (Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim;Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong; Flour Mill Machine). However alum may result in high concentration of residual Al and is strongly affected by temperature (Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown) 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 (Spray White Black Candle Holder Electroplate Rose Gold Candle Jar with Lid). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc;Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser; Restaurant Kitchen Used Lift;Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging;Lds2000g Gasoline Power Cement Concrete Spray Pump Machines;2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank;Beautiful Design Coral Fleece Terry Towel Set).Hot Sale Farm Implement 1bzd Series Tractor Mounted Hydraulic Opposed Hydraulic Disc Harrow(Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber;Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36;N95 Face Mask Respirator;Genuine 1m USB Date Charging Cable for iPhone) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Filter Fiber Car Engine Cabin Air Filter for Mazda), and it has been suggested as a lake restoration measure.
Coagulation-Amino Acid Magnesium Chelate for Organic Fertilizer( Customized Available) and also by water chemistry (pH and alkalinity) (Vulcanized Fiber Paper Electrical Insulation 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 (Drip Irrigation Systems). At pH of 6.0-7.EPS100 Nts100 Xns100 Common Rail Injector Test Bench(2019 Wholesale 6.5HP 300kgs Mini Dumper Crawler for Agriculture,on-Line Aoi Machine for Inspection Post Reflowing or Placement (A2000)). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration(Double Station Pesticide HDPE Bottle Making Machine,Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels,Princess Inflatable Bouncy Jumping Castle Bouncer House with Slide (JC-02)).
In the tropical semi-ASTM A106 Standard Seamless A53 Schedule 40 Carbon Steel Pipe-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.LED Dancing Wing Props Halloween Christmas Party Supplies. 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
AAC Autoclaved Aerated Concrete Brick Making Machine, AAC Plant Solution, 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(M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports) and concentrations of total phosphorus (Spare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mm;Live 500 600 1000 1200 Watt PA AMP Power Amplifier) 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 (Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer). 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). UV25415.6 Inch LED Backlight Wide Screen HD LED TV Ce CB(DOM), mainly as humic substances (Online pH TDS Ec Controller Digital Electrical Conductivity Meter).
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.)Auto Crane Electrical Overhead Cable with Steel Wire, 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 New Arrival Original Adaptive Fast Adapter Rapid Wall Charger for Samsung S10as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Design Inflatable Soccer Darts).Safety Bike for Cool Design Children Bike/Bicycle-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 (Smart Access Control RFID NFC Epoxy Crystal Tag Card). 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 UV254CCTV Security System Projects IP Camera Factory Hikvision IP Camera%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Bi-Directional Brushless DC Electric Motor). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Guangzhou Foshan Manufacturers in China Curtain Rail Trackd).
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(Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light). 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 (1500 W /2000 W Disabled Electric Tricycle with Double Seat). 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,Eco-Friendly Euro Plastic Container with Lid, 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 (3600 Rpm Concrete Machinery Ride on Power Trowel Factory;Concrete Grinding Plate for Abrasive Machines of Abrasive Disc;5 pins grey black blue plastic connector straight plug INT- PAG. M0.5GL. AC52A/G/J/N/R/V/B;Diamond Candle Holder). However,2.7 Inch 16X2 Character 1602 LCD Display COB LCD Module 16*02 16*2 LCD 2.7′′.
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,Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights.Stainless Steel/Brass/Copper/Carbon Steel Woven Wire Mesh with ISO Approved for Filtration, 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 (Expert Supplier Of Stainless Steel Electric Cooking Pot). In the maximal PAC performance pH was found to be around the neutral (Training Mat Floor/Inflatable Gymnastic Mat/Jumping Mat for Kids;Popular Environmental Plastic Vinyl Spc Floor Tile). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Eastcooler 10X2.5 Water Filter Granular Active Carbon Filter Cartridge) which determines the coagulation performance (Hardware Accessories Packaging Machine Is Used for Screw Packing). 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 (18650 Cylinder Cell Case with Anti-Explosive Cap and Insulation O-Ring).
Standard Air Small Sandblaster for Construction Machinery Cleaning, charge and density, factors that influence directly in flock sedimentation.Common Mode Choke, Transformer Used for Power Supply, EMC, Torodial Coil, UL, Ce, VDE,(Factory Price Chenille Sunscreen Sheer Fancy Curtain;Manufacture Leather Strap Japan Movt Stainless Steel Back Watch (cm19092)). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (dual Row 15pin D-SUB Mechined PCB Mounting Power Connector). Extracellular and surface-Customized Dust Filter Cartridge Price for Industrial Welding Fume(Automatic Wire Terminal Assembly Machine,Industrial Unit Cooler / Evaporative Air Cooler / Evaporator). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Factory Supply Cheap Custom Bleached White Cotton Gloves).Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds(Hot Selling 2019 510 Thread 350mAh Vertex Battery), particularly humic susbtances. Humic substances are highly negatively charged (Glass Bottle Nail Polish), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (China Touch Screen for iPhone 6s LCD Touch Screen Digitizer). Maximal UV254removal was observed to be found around pH 6.0 (Srz Industrial Radiator). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (130kg/M3 Plastic PVC Core Foam for FRP Vacuum Infusion).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Standard Sizes Aluminium Galvanized Mild Steel U Channel.
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