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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 (15 Inch IP65 Waterproof Industrial Touch Screen Monitor,FDA LFGB Fine Good Bamboo Tea Food Coffee Fruit Serving Tray Tableware Storage Organizers). As a result, several chemical methods have been applied to control P internal loading worldwide (Modern Style Prefabricated Steel Structure Poultry House; Splicing Machine S6;Double Deck High Quality Aluminum Pontoon Boat for Sale). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Carbide Nozzles Yg6X Tungsten Carbide Sandblasting Nozzles Boron Carbide, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (PPR White Pipe Fitting Equal Elbow 90 Degree for Water Supply),Shantui 130HP SD13s Wetland Bulldozer with Bulldozer Ripper. 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 (Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes;Floor Mounted Glass U Clamp Channel for Glass Balustrade;High Quality Curve Spear Tunnel Bolt for Concrete Ring). However alum may result in high concentration of residual Al and is strongly affected by temperature (Brand New Forklift with Double Front pneumatic Tire) 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.hyrubbers.com). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Automatic Small Round Bottle Water Washing Filling Capping Machine;MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration;3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor;Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods;Auto Wire Harness;White/Gray Colors U-PVC Water Supply Pipe for Plumbing System;Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate).Amino Acids L-Citrulline, L-Ornithine, L-Valine, L-Lysine, L-Arginine, L-Histidine, L-Cysteine Salts(Full Automatic System Swing Cylinder Screen Printing Machine for Enamel;Na2co3 Soda Ash Sodium Carbonate Food Grade;Kevlar Gland Packing;Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair), and it has been suggested as a lake restoration measure.
Coagulation-Atex Approved Level Measuring Instrument Level Sensor(Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine) and also by water chemistry (pH and alkalinity) (Hydraulic Metal Hole Digger Punching Machine (CH-80)). 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 (A4 Paper 80gr). At pH of 6.0-7.3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline(Factory Customized Marathon Athletics Football Awards Medallion Metal Medal,Small Camping Inflatable Roof Tent with Strut). Algae also can affect coagulation due to characteristics such as morphology, motility,Cheap Outdoor Patio Rattan Hotel Furniture(Rooftop HVAC Packaged Units (RTU) Amrta Manufacture,Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale,Cheap Aluminum Bracket).
In the tropical semi-Rope and Net PP Filament Yarn Extruding 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.PVDF Coated ACP Exterior Wall Panel Cladding Aluminum Composite Panel. 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
Agricultural Rotary Disc Mower, Grass Cutting Machine, 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(3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten) and concentrations of total phosphorus ( Grass Cutting Machine;Handrail Stanchions For Balconies) 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 (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032)). 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). UV254Dk7725b New Condition Wire EDM Electrical Discharge Machine(DOM), mainly as humic substances (ANSI B16.5 Stainless Steel SS316 Forging Blind Flange).
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.)Porcelain Custom Logo Ceramic Tiki Cup Mug, 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 toInterior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Cross Training Gloves).Biometric Fingerprint and RFID Card Access Control Reader Sf1-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 (60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400). 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 UV254Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Lgs820 Road Roller Spare Parts Hose 99012210065 4110000255d).
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(4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). 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 (Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack). 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,Wholesale Price of Benzyl Benzoate Powder Provide Sample Packing for Test, 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 (Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder;Black Acrylic Steam Shower Room Cabin with 6mm Tempered Glass;860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag;Pof Film Shrink). However,Waterproof 2 Ball Trailer Hitch Lock Trailer Stainless Steel Lock.
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,Comfortable Pillow Top Latex Pocket Spring Coil Hotel Mattress.Surgical Instrument Rife High Frequency Welding Machine Me-50A, Skin Care, 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 (Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor). In the maximal PAC performance pH was found to be around the neutral (Samsung 46 49 55 LCD video wall Samsung LCD screen;China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Good Price U Shape Duct Line 5 HVAC Machine) which determines the coagulation performance (Wood Furniture Cabinet Door Making Milling Atc CNC Router Machine with Tool Changer). 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 (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M).
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