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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 (1/2 Inch Soft Flexible Green Cloth Surface SAE 100 R3 Hydraulic Hose Rubber Hose,High School Royal Blue/Gold Graduation Honor Cords). As a result, several chemical methods have been applied to control P internal loading worldwide (High Quality Electrochromic Pdlc Privacy Film;Transparent Single Crystal Alumina Sapphire Jewel Bearing and Components;Water Resistant Rubber Gasket for Industry). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Mirror Chrome Aluminium Powder Gold Silver Pigment for Nail Art). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ceramic Foam Filter for Water Purification, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Articulating Arms),Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628). 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 (4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale;OEM/ODM Custom Precision Copper/Aluminum /Bronze /Carbon Steel/Stainless CNC Machining Parts;Showbull Professional 5800 Gasoline Wood Cutter Chainsaw Made in China). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Design Contact Infrared Baby Ear Thermometer Jl0158) 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 (Copper Alloy C93200 C95800 C93800 Leaded Tin Bronze). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System;High Speed Automatic Cleaning Scourer Making Machine Manufacturer;Agricultural Sprinkler Irrigation System Oscillating Impact Sprinkler for Garden;6 Ton 7 Ton 8ton 10 Ton Rubber Track Crawler Dumper Morooka Track Dumper;3A Quality Jacquard Knitted Hat with POM-POM/Warm Hat ((DH-K098);Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine;20K Ohhm 1% Electrical Ntc Thermistor Resistance).Aol CNC 1625 Cutting Plotter for Corrugated Cardboard(OEM Customized Aluminum Die Casting Automotive Parts Die Casting Die;Hex B19 B22 Integral Drill Rod Steel /Shank Drill Road/Tapered Drill Rods;www.bnpo3.com; Truck Parts) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (16oz Pet Plastic Food Jar with Embossed Metal Lid (PPC-PJ-1701)), and it has been suggested as a lake restoration measure.
Coagulation-Wholesale Room Ozone Generator for Fruits and Vegetables(Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding) and also by water chemistry (pH and alkalinity) (Custom Design Stainless Steel Sheet Metal Fabrication Box Cover). 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 (4 Holetransition Center Strip for Aluminum Profile). At pH of 6.0-7.Two Upright Frame Steel Plate Warehouse Storage Light Duty Rack(Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula,Cartoon Design Decorative PVC Sheet for Wall Panel Moulding). Algae also can affect coagulation due to characteristics such as morphology, motility,Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens( Skin Care,3003 3004 3005 Aluminium Circles for Foil Pans with Lids,Camouflage Military Poly/Cotton Printed Fabric).
In the tropical semi-Automatic Multi-Heads Cream Honey Paste Oil Filling Spout Pouch Packing Machine-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.OEM Stainless Steel Pump Body Precision Investment Casting Parts with RoHS Certificated. 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
LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031, 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(Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery) and concentrations of total phosphorus (Carbon Stick Welding Electrodes E6013&E7018 Stone Bridge Brand;Car Cleaning Tool Kits) 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 (Scarifier Loosener Ripper Horizontal Rotary Cultivator Tiller). 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). UV254CNC High Speed Gear Hobbing Machine Ys3118CNC5(DOM), mainly as humic substances (Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63).
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.)Commercial Fitness Gym Hammer Strength Machine Mts Biceps Curl Equipment with 80kg*2group, 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 toProfessional Stage Lighting 7PCS 4in1 LED Flat PAR Lightsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Full-Automatic Incense Sticks Counting and Packing Machine).CNC Router Machine Heavy Duty Steel Frame 2030 CNC Router-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 (Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print). 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 UV254Custom CNC Precision Machining Auto Parts Car Accessory Machine Parts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Crimping Machined).
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(Large Industrial Ceiling Fan with External Rotor Motor Drive). 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 Quality Non-Standard Metal Components Precision Machining Mold Parts). 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,Auto Starter 0001230002 12V 3.0kw 11t for John Deere, 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 (Stainless Steel Bimetal BBQ Gas Bimetal Oven Thermometer;Building Hot Rolled C Purlin C Channel Steel Price;Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector;Ac. Automatic Voltage Regulator). However,High Speed Double Jersey Computerized Transfer Rib Circular Knitting Machine 2/3 Ways Djjtr.
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,Yellow Nitrile Fully Dipped Gloves Labor Protective Safety Work Glove.Plastic Traveling Pet Crate Dog and Cat with Wheels and Handle Travel Cage, 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 (PP Surface Self Adheisve Roof Underlayment). In the maximal PAC performance pH was found to be around the neutral (High Quality Cold White Light Triac Dimmer (like an incandescent lamp) LED Panel;Cheap 20W/30W High Quality Fiber Color Wire Laser Marking for Metal Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing) which determines the coagulation performance (Horizontal Fire Pump). 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 (Jbz-22D Automatic High Speed Paper Cup Forming Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Aluminum DJ Truss for Exhibition Lighting Truss.
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