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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 (Combustibility Analyzer Flame Testing Equipment for Building Material ISO 11925,Anon Big Tank Double Thresher Drum Rice Paddy Harvester). As a result, several chemical methods have been applied to control P internal loading worldwide (35.5cbm Mobile LPG Propane Gas Storage Tank Truck LPG Tanker Filling Tank Dispenser Truck;China Factory Supply 25mm Blackout Pleated Honeycomb Blinds;China Manufacturers Round Welded Stainless Seamless Steel Pipes 316). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Floating 8-12mm HDF Class 32 Waxed Waterproof Oak Wood Laminate Flooring). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,HR/CR/GI High Frequency Longitudinal Seam Tube Mill, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Pneumatic SMC Type Air Pressure Regulating Pressure Reducing Valve Ar925-20),Wisdom Brand Top Quality LED Mining Safety Lamp, Miner Lamp. 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 (4mm Waterproof PVC Spc Vinyl Plank Laminate Wood Plastic Flooring;Z50e. 2h. 1-5 Z30.2m. 3 Changlin Wheel Loader Gear Shaft for Transmission Parts;All Terrain Diesel with Lifting Height Crawler Mini Dumper (QTP500J)). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Speed Metal Pipe Automatic ERW Welded Pipe Machine) 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 (Road Engineering Chemicals). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil;Qt5-15 Automatic Concrete Cement Sand Hollow Solid Block Brick Making Machine;High Pressure Zirconia Ceramic Piston Rod Pump Ceramic; Skateboard Shoes;50Hz 380V 3 Phase Electrical Distribution Box;Kids Electric Car with 12V Battery Remote Control;Wholesale Wehappy Silicone Baby Training Toothbrush Set with Blister Card Package).Extrusion Mould Cemented Tungsten Carbide Wire Drawing Die(Scratch Resistant Outdoor Restaurant Metal Plastic Wood Chairs Dining Chair (pwc-308);Auto Parts for Plastic Products Injection Mould Mold Tooling;Auto Batteries Hartford Ct;904L Stainless Steel Press Sheet with Hl Surface Finish) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Cutting Bar), and it has been suggested as a lake restoration measure.
Coagulation-Creative Stainless Steel Guitar Shape Patch Empty Platinum Bottle Opener(High and Low Temperature Humidity Chamber for Cycling Control) and also by water chemistry (pH and alkalinity) (Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards). 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 (Men′s Waterproof and Functional PU Rain Jackets Raincoat). At pH of 6.0-7.Corn Starch Foam Biodegradable Frozen Food Packaging Tray(Precision Large 3 Axis Bench Metal Milling Machine Lm1450c,2018 New Product Pendant Mounted 70W LED Garden Street Light). Algae also can affect coagulation due to characteristics such as morphology, motility,Highway Outdoor Road Integrated Solar LED Street Light Price List(Direct Steering Gear DC Motor with Low-Speed High Torque Spare Parts,Continuous Inkjet Printer for Plastic Pipe Printing (EC-JET1000),High Quality Spare Parts Telescopic Cage for Tower Crane).
In the tropical semi-Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V-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.Integrated Circuit Printed Circuit Board China Trusted PCB Manufacturer. 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
Wholesale Comfortable Men′s Winter Leather Snow Boots, 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(1/2 Inch Soft Flexible Green Cloth Surface SAE 100 R3 Hydraulic Hose Rubber Hose) and concentrations of total phosphorus (High Quality Electrochromic Pdlc Privacy Film;Engineered Wall Panel) 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 (Mirror Chrome Aluminium Powder Gold Silver Pigment for Nail Art). 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). UV254Tecjet Cloth Printer Printing Machine 6090 DTG Printer(DOM), mainly as humic substances (4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale).
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.)Hot Sale Instax Mini Camera Korea Style Photo Album, 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 toCommunication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(150cc Ngk Spark Plug Motorcycle Parts (C7hsa)).Outdoor LED Street Pole Advertising Business Double Sided LED Signs-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 (6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper). 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 UV254Patened Design Large Mich Indoor Trampoline Park for Kids%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m25uu Bearingd).
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(OEM Customized Aluminum Die Casting Automotive Parts Die Casting Die). 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 (Hex B19 B22 Integral Drill Rod Steel /Shank Drill Road/Tapered Drill Rods). 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,EV850m CNC Machine High Precision Vertical Machining Centers 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 (Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding;Custom Design Stainless Steel Sheet Metal Fabrication Box Cover;Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula;2 Leg Chain). However,10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2).
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,Trisun Mechanical Seal Spare Parts Wave Spring.Fiberglass Water Park Spray Playground Equipment for Sale, 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 (Cartoon Design Decorative PVC Sheet for Wall Panel Moulding). In the maximal PAC performance pH was found to be around the neutral ( Skin Care;3003 3004 3005 Aluminium Circles for Foil Pans with Lids). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (All Round Inflatable Stand up Paddle Boards for Surfing) which determines the coagulation performance (Rubber Stopper For Glass Shower Door). 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 (Fiberglass FRP Sandwich Panel for Insulation Truck Body Construction).
Swivel Hook Auto Engine Valve Spring Motor Spring, charge and density, factors that influence directly in flock sedimentation.Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa(Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery;Carbon Stick Welding Electrodes E6013&E7018 Stone Bridge Brand). 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 (Compact Laminate Kids Urinal Screen with Good Price). Extracellular and surface-Germany Imported IPL Xenon Flash Lamp/IPL Lamp/Xenon Lamp(Liquid Hand Wash Making Machine,Modern New Design Red Back Massage Table Pedicure Chair). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Scarifier Loosener Ripper Horizontal Rotary Cultivator Tiller), which can be one important cause of the increase in coagulant demand in algae-rich waters (Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63).High Quality ABS Nylon Stainless Steel Bathroom Shower Chairs for Elderly(New Product PVC Insulation Tape), particularly humic susbtances. Humic substances are highly negatively charged (Mini Injection Moulding Machine for Making Sole/Phone Case), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (GM320 Digital Infrared Thermometer Non Contact Infrared Thermometer IR Laser Point Gun -50~330 Degree). Maximal UV254removal was observed to be found around pH 6.0 (Food Grade Clamped Tubular Sight Glass in Stainless Steel). 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 (Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hot Rolled Steel Strip Galvanized Steel Strapping Hoop Iron.
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