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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 (Wholesale Factory Price 100% Virgin Kinky Curly Vietnamese Human Hair,Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (up-Down Table 1390 100W CO2 CNC Laser Cutter Machines;High Quality for Kawasaki K3sp36 Replacement Parts;High Quality Firefighting Rescue Equipment Safety Rescue Tripod). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,3 Inch Smooth Corrugated PVC Suction and Discharge Hose, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Arc Segment Half Round Circle Trapezoid Neodymium Magnet),Women 100% Polyamide and 100% Polyester Melange Hoodie Hybrid Vest. 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 (Great Quality Waste Water Treatment Polyaluminium Chloride PAC;I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds;Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging 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 (Qt4-15 Cement Hollow/Paver/Solid Block Making Machine/Brick Making Machinery). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Building Lifting Equipment Trolley Electric Cable Winch;Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220;OEM Customized Design Sublimated Print Cotton Twill Trucker Baseball Cap;Factory Direct Price Automatic Snack / Candy Grain Packing Machine;Wedding Decoration LED Light Water Screen Curtain Fountain;Manufactured Goods PPGI Coil Corrugated Steel Sheet;Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting).Simple Design High Quality Cotton Velour Disposable SPA Hotel Travel Slippers with Logo(Galvanized Bird Cage Welded Wire Mesh Rolls for Construction;Hot Sale Foundry Moulding Machine Manufacturers;m.gmcmagnet.com;Industrial ESD Safety Shoes with Steel Toe Mens Black Color) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes ( Road Cutter), and it has been suggested as a lake restoration measure.
Coagulation-Commercial Overhead Automatic Aluminum Insulated Roller Shutter Door for Garage or Workshop(Take Away Custom Logo Printing Snack Paper Pizza Box Packing) and also by water chemistry (pH and alkalinity) (1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree)). 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 (Eyelash Vendor Customized Boxes). At pH of 6.0-7.Factory Supply Raw MDF / Melamine Faced MDF Plain MDF with Cheap Price(New Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer,Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection). Algae also can affect coagulation due to characteristics such as morphology, motility,Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine(European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle,Sesame Almond Cashew Nut Peanut Butter Making Processing Machine,Raw Material Food Grade Color Masterbatch for Shopping Bags).
In the tropical semi-Automatic Defrost Supermarket Arc Sliding Island Freezer Horizontal Island Freezer-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.Hot Sale Copolymer Coated Aluminum Foil Tape for Cable. 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
Customized Stainless Steel CNC Machining Parts Watch Case, 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(2018 Hot Sell Bathroom Glass and Mirror Accessories) and concentrations of total phosphorus (Best Price Semi Automatic Silicone Sealant Filling Sealing Machine;m.nbjiafei.com) 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 (Universal Cable Fault Testing Instrument Tester / Analyzer). 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). UV254Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker(DOM), mainly as humic substances (Adult Electronic Medical Weighing Scale Body Fat Rate Height Weight Digital Scales with Printer).
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.)Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration, 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 toSandblast Finish Inside Glass Lampshade with Rod Different Colors Are Availableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(luqi-tech).Excavator Bulldozer Ripper Forged Bucket Tooth for D85c D85tl 4t5502 9W4551 4t5502tl 195-78-21333-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 (FDA Natural Banish Hangovers Dihydromyricetin (DHM) 98% HPLC). 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 UV254Tungsten Carbide Milling Insert for Book Binding%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang 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 (Competitive Price Roofing Nails with Umbrella Head for Constructiond).
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(Stainless Steel Sheet 254smo). 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 (40X50cm Log 60kg 100kg 200kg Portable Courier Platform Scale). 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,Double Side Painted Aluminium Coil Plate with PE Film, 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 (Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail;Organic Fertilizer Production Line for Manure Treatment;Tz03D High Quality China 20-40HP Garden Tractor Front End Loader Hot Sale in New Zealand;High Quality Sheet Metal Stamping Custom Stainless Steel). However,Professional Double Cup Fully Automatic Coffee Machine.
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,Vsm Zirconia Mini Quick Change Flap Disc 2 3 for Carbon Steels.Customized Thread Cutter of M105*3.0 Large Cutting Tools for CNC Machine Tools, 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 (Android Data Cable Mobile Phone USB Cable Mobile Phone Cables). In the maximal PAC performance pH was found to be around the neutral (High Chrome Cast Iron Mud Sand Slurry Pump Parts; VDE). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Pet Strap Production Line with Good Quality) which determines the coagulation performance (Kn95 Respirator Face Mask). 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 (XCMG Official 150 Ton Rough Terrain Crane Rt150).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.34*25cm Office File Pocket Felt A4 Document Bag.
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