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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 (Plastic Round Home Storage Box Vacuum Insulated Lunch Box,E-Liquid Fat Juice Vape Juice Cigarette Juice Filling Stoppering Capping Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Metal Solar Powered Crab Shape Outdoor Garden Ornaments LED Solar Lighting;Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge;High Precision Customized Medical Injection Mold for Needle Holder). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Mining Equipment with Drawing Design). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,304, 316 Slot Stainless Steel Tube with Glass, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Valve Mini),Giant Christmas Socks Carnival Amusement Park Inflatable Slide. 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 ( Motor Cable Wire Electrical Power Cable;Class 1 Foam Rubber Insulation Pipe for Air Conditioner;Sublimation Coated Aluminum Sheets for Heat Transfer Printing). However alum may result in high concentration of residual Al and is strongly affected by temperature (Solid Wood Countertop Wood Table Top Wood Island Top Wood Bar Top Wood Table Top) 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 (www.realtopmachinery.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (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;Luxury Comfortable Mini Bread Spring Mattress in Bedroom Furniture;Copper Casting Company;Floor Stainless Steel Fix Movement Joints Decorative Stainless Steel Tile Trim;Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong).Multifunction Massage Rainfall Shower Column with Five Functions( Flour Mill Machine;Cross-Border Jewelry Hot Silver Set Diamond Full Diamond Crown;Magnesia Fused Spinel For Sale;Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser), and it has been suggested as a lake restoration measure.
Coagulation-Belt Conveyor Vertical Guide Roller/Side Idler Rollers/Conveyor Roller( Restaurant Kitchen Used Lift) and also by water chemistry (pH and alkalinity) (Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging). 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 (GJFJV 2 12 24 Core Singlemode Multimode Indoor Fiber Optic Cable). At pH of 6.0-7.Geometric Tall/Large Plants Glass Terrarium Planter Pot Box for Christmas Decorative(2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank,Beautiful Design Coral Fleece Terry Towel Set). Algae also can affect coagulation due to characteristics such as morphology, motility,Easywell & Minston Electric Platform Scale with Height Meter BS-200lp(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 Frame36,1022a Drywall Screw).
In the tropical semi-Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder-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.Special Customized Anodized Aluminium 6061 CNC Machined Steering Wheel Quick Release Part (S-085). 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
50-5000L Commercial Craft Beer Brewery Equipment, 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 Available) and concentrations of total phosphorus (Vulcanized Fiber Paper Electrical Insulation Paper;OEM Customized Aluminum Alloy Helical Gear Reducer Planetary Transmission Gearbox) 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 (Double Station Pesticide HDPE Bottle Making Machine). 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 Cup Set Handmade Coffee Cup and Saucer Set(DOM), mainly as humic substances (Multifunction Trolley Luggage Bag Travel Luggage Men′s Trolly Luggage with 4 Wheels).
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.)Quality Manufacturer Plastic PS Extruder Foam Sheet Extrusion 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 toSpare Customizable Pultrusion FRP Angle Bar for 50*50*2.8mmas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Prime Electrolytic Tin Plate for Metal Tin Can).Coconut Shell Activated Carbon for Drinking Water Treatment-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 (Kitchen Equipment Counter Top Stainless Steel Electric 4 Pans Bain Marie Buffet Food Warmer). 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 CNC Turning Center Parts Machinery Auto Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Online pH TDS Ec Controller Digital Electrical Conductivity Meter). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (jamd).
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(Yhzs50 Mobile Concrete Mixing/Batching Plant with Low Price). 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 ( Wood Peeling Lathe). 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,Customized Acrylic Plastic Sign Board Design Customized Size, 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 (7inch TFT LCD Display Module for Car Compass with resolution 1024(RGB)*600;Smart Access Control RFID NFC Epoxy Crystal Tag Card;Bi-Directional Brushless DC Electric Motor;Exercise Bike For Arms). However,1W Colorful Garden Park Plaza Lawn Underground Lamp.
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,Automatic Large Plastic Road Barrier Making Blow Molding Machine Machinery.Wholesale African Women Fashion Dress One Piece Long Dresses Style Clothing, 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 (Modern Style Home Furniture Set Metal Stainless Steel Outdoor Kitchen Furniture). In the maximal PAC performance pH was found to be around the neutral (Emergency Vehicle Tow Truck Windshield Lights LED Warning Visor Light;1500 W /2000 W Disabled Electric Tricycle with Double Seat). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (China Homemade Bearing Ball Screw for CNC (DFU series 16-100mm)) which determines the coagulation performance (Micro DC 24V Worm Gear Brushless Motor for Medical Equipment). 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 (Pneumatic Ef Series Air Preparation Units Filter).
SKF Bearing, Miniature Ball Bearing for Window Sliding Rollers (626ZZ), charge and density, factors that influence directly in flock sedimentation.Custom Dust Removal Carpet/Clothes Cleaning Lint Rollers(3600 Rpm Concrete Machinery Ride on Power Trowel Factory;Concrete Grinding Plate for Abrasive Machines of Abrasive Disc). 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 (5 pins grey black blue plastic connector straight plug INT- PAG. M0.5GL. AC52A/G/J/N/R/V/B). Extracellular and surface-Eco-Friendly Unbreakable Drinking Cup Shatterproof Silicone Wine Cups for Party(m.damai-grinder.com,Expert Supplier Of Stainless Steel Electric Cooking Pot). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Training Mat Floor/Inflatable Gymnastic Mat/Jumping Mat for Kids), which can be one important cause of the increase in coagulant demand in algae-rich waters (Popular Environmental Plastic Vinyl Spc Floor Tile).China Most Professional Factory 316L Stainless Steel Round Seamless Decorative Pipe Tube(Eastcooler 10X2.5 Water Filter Granular Active Carbon Filter Cartridge), particularly humic susbtances. Humic substances are highly negatively charged (Scissors), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (18650 Cylinder Cell Case with Anti-Explosive Cap and Insulation O-Ring). Maximal UV254removal was observed to be found around pH 6.0 (Factory Price Chenille Sunscreen Sheer Fancy Curtain). 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 (Manufacture Leather Strap Japan Movt Stainless Steel Back Watch (cm19092)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Manufacturers 1000W AC/DC Converter Car Power Inverters.
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