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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 (Fasion Style Custom Indian Embroidery Patch,Simple Design Indoor Trampoline Bed Trampoline Park Price for Sale). As a result, several chemical methods have been applied to control P internal loading worldwide (Cummins auto diesel engine motor 6ISBE parts 4892338 starter motor;Karl Mayer Machine Warp Knitting Spare Parts Karl Mayer Machine Pulley Belt;Denim Molile Phone Accessories USB Data Charging Lightning Cable for Type-C). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Plastic Reflective Raised Pavement Marker Road Stud). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,M2m Outdoor Wi-Fi Outdoor CPE DTU with Dual LAN Ports, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Nasal Forceps),HRC60 4 Flutes Corner Radius Solid Carbide Cutting Tools End Mill. 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 (Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style;PU Foam Plastic Squishy Slow Rising Toy for Unicorn;Top Quality Polar Wohlenberg Paper Cutting Blade). However alum may result in high concentration of residual Al and is strongly affected by temperature (Large Format Auto Open Heat Press with Slide-out Press Bed) 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 (Neoprene Bottle Can Cooler Bag Beverage Storage Carrier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Winter Warmer Windproof Ski Full Face Mask Cover Hat Cap Outdoor Sports Balaclava;Public Address System High Power Range Outdoor Column Speaker;Automatic Multi Station Nut Forging Machine/Nut Cold Forging Machine;Water-Proof Silicone Coated Fiberglass Cloth;Ceramic Heat Emitter Lamp;Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace;98% Polypeptide Hormones CAS 113-79-1 Argpressin Acetate as Neurotransmitter).M5 SMD with Internal Blind-Hole Thread with Pin (groove)(Custom Polyester Woven Patch Logo Snapback Hats;28mm Container Floorboard Plywood Hot Sale Container Parts Good Quality;Air Suspension Component;Car Roof Rack Cross Bar for Nissan X-Trail 2008 (8162Y08)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Self Tapping Screw Roofing Screw Bimetal Screw), and it has been suggested as a lake restoration measure.
Coagulation-2 Storey Worker Living Block Container House Supplier(Double Side Painted Aluminium Coil Plate with PE Film) and also by water chemistry (pH and alkalinity) (Cation Printing Effect Micro Fleece). 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 (Cjc1295 with Dac Legit Peptide Hormones for Human Growth). At pH of 6.0-7.Ethylene-Propylene-Diene Monomer Rubber Waterproof Materials(2 Head Embroidery Machine Cap Flat T Shirt Embroidery,Tri-Axle 50tons 60tons 18m Low Loader Lowbed Trailer Axles). Algae also can affect coagulation due to characteristics such as morphology, motility,New Arrival Household Self-Washed Flat Mops Cleaning(Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover,Silicon Baby Bib Super Waterproof with Food Slot,Elastic Ligature Ties Forcep).
In the tropical semi-New Type Portable 380V Electric Winch in Stock-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.10ml Portable Spray Perfume Glass Empty Bottle Atomizer. 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
Ce Approved Acrylic Mini LED Letters Sign for Outdoor, 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(Industrial Dust Filter Aramid Nomex Fiberglass PTFE Fabric Filtration Fabric) and concentrations of total phosphorus (High Quality Nylon Monofilament Suture Medical Nl Suture Thread with or Without Needle;Satin Labels Automatic Screen Printing Machine with Infrared Dryer) 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 (10 Years Factory Free Samples Competitive Price Black Duct Tape with Custom Logo). 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). UV254Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner(DOM), mainly as humic substances (Optical Fiber Cable MTP/MPO Cassette for Data Center).
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.)Best Quality Hydroponic Film Greenhouse Steel Structure Construction, 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 toHigh quality 110V DC Power Supply for American Marketas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hemispherical Dish Head).Epoxy Coated Cast Iron Dismantling Joint for Water Supply Pipe Line-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 (Customized Microfiber Sport Towel for Swimming Towel). 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-Top Men′s Casual Sports Shoes Athletic Shoes Sneaker Shoes (FFXXY1228-1)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Customized Small Module Sintered Metal Product Spur Gear Pinion). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Hydraulic Brick 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(Fashion Environmental Protection Non-Woven Bag Cotton Shopping Bag). 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 (Waterproof Magnesium Oxide False PVC Ceiling Panel). 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,Small Playground Plastic Slide Preschool Equipment Toys for Kids, 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 (Drive Shaft for Ford Mondeo III Tdci Left Part No. 218027 Outside 27t/Inside 26t OE. 1326261;Best Key Machine Sec-E9 High Security Key Cutting Machine Built-in Data;High Quality Generator or Car Battery Power Switch for Battery Isolator Cut off;30ml Matte Surface Skincare Body Oil Glass Bottle). However,Wholesale Events 6FT Wood Dining Round Table.
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,Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel.Taizhou Huangyan Laboratory Room 60 mm Plastic Injection Petri Dish Mould, 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 (Aluminum Height Adjustable Walking Cane (SC-CR58-67)). In the maximal PAC performance pH was found to be around the neutral (Original Mobile Phone Touch Screen LCD for Samsung S10 S10plus + S10e;Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2)). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (300*7*5950mm Good Quality Light Weight PVC Ceiling Panel Wooden Color Design DC-131) which determines the coagulation performance (Frosted Glass Bottles). 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 (Home Security Video Door Phone Camera Doorbell Intercom System for Villa).
Ce Certificated Acm-60 PTFE Powder Grinding Mill, charge and density, factors that influence directly in flock sedimentation.Automatic Magnetic Induction Heater for Band Saw Quenching Production System(White Frame 43 Full HD LCD Ad Player Advertising Digital Signage Interactive Totem;Natural Wave Brazilian Virgin Human Hair Extension). 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 (2018 New Design Luxury Pet Bed Gray Long Fur Dog Cat Beds). Extracellular and surface-Original Germany Bitzer Brand Compressor 4hc-1.2y(Cold Pressure U-Type Terminal,5110c Diesel Generator Control Module Dse5110 Parameter Display by LCD). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (AAC Block Making Machine Line Supplier/AAC Block Machinery), which can be one important cause of the increase in coagulant demand in algae-rich waters (Custom Promotional Soft Cover Children Music Book Printing).Prefab Prefabricated Lightweight Steel Structure Construction Processing Plant Metal Workshop(Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale), particularly humic susbtances. Humic substances are highly negatively charged (Gym Water Jugs), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Cardboard CO2 100W Tube Tube Laser Cutting Machine). Maximal UV254removal was observed to be found around pH 6.0 (a-008 Female Adult Toy Massager Masturbation Vibrator 10 Frequency-Style a). 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 (Replacement EPE Eppensteiner Filter Element (8260P10S000P)).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized CNC Machining Checking Fixture for Automotive Bracket.
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