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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 (Sc Single Mode Single Fiber 100m Mini Fiber Media Converter,cnmirant). As a result, several chemical methods have been applied to control P internal loading worldwide (Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area;Cylinder Actuated Cement Powder Butterfly Valve;Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Injection Product Mold Factory Plastic Injection Molding Factories). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Building Lifting Equipment Trolley Electric Cable Winch, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (www.miracle-leather-bag.com),Fashion Promotion Logo Design Portable Canvas Wallet with Hook. 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 (80% Cotton 20% Polyester Colorblock Men′s Fleece Pull Over Raglan Hooded Sweatshirt;Factory Directly Ss 304 Stainless Steel Toilet Cubicle Fitting Indicator Latches;New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9). However alum may result in high concentration of residual Al and is strongly affected by temperature (CPVC Pipe Extrusion Line/PVC Pipe Production Line) 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 (Bra Hook And Eye Replacement). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Nail Sterilizer Disinfection Box Salon Nail Tools Disinfector Sanitizer Box;Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap;Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box;4mm/0.3mm Honeycomb-Shaped Sound Absorbing Aluminum Composite Panel for Interior Decoration;China Factory Aluminium Can Canning Equipment for Beer;Wholesale Factory Price 100% Virgin Kinky Curly Vietnamese Human Hair;up-Down Table 1390 100W CO2 CNC Laser Cutter Machines).PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble(High Quality for Kawasaki K3sp36 Replacement Parts;High Quality Firefighting Rescue Equipment Safety Rescue Tripod;Fully Automatic Weighing and Packaging Machine for Packing Screw Fittings;Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Great Quality Waste Water Treatment Polyaluminium Chloride PAC), and it has been suggested as a lake restoration measure.
Coagulation-100% Polyester Fiber Recycled Polyester Wadding for Garments(I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds) and also by water chemistry (pH and alkalinity) (Large Diameter Plastic HDPE Pipe Extrusion Making Machine Production Line). 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 (Aluminum Laser Cutting Machine High Quality Supplier). At pH of 6.0-7.Shr/IPL Laser for Hair Removal Skin Rejuvenation(Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging Machine,Building Lifting Equipment Trolley Electric Cable Winch). Algae also can affect coagulation due to characteristics such as morphology, motility,Cotton Garden Work Glove with Single Side PVC Dots(Stainless Steel Hex Head Bolt DIN933 ANSI Full Thread M8X10...M8X220,OEM Customized Design Sublimated Print Cotton Twill Trucker Baseball Cap,Tower Crane Load Moment Limit Switch for Safety Operation).
In the tropical semi-Golf Practice Nets and Cage/Professional Training Golf Net-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.Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt. 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
Sublimation Coated Aluminum Sheets for Heat Transfer Printing, 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(Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting) and concentrations of total phosphorus (Galvanized Bird Cage Welded Wire Mesh Rolls for Construction;Rohan Anti Mosquito Clothing) 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 ( Road Cutter). 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). UV2543G/H Ozone Generator for Air Purification and Sterilization(DOM), mainly as humic substances (Take Away Custom Logo Printing Snack Paper Pizza Box Packing).
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.)Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory, 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 toEuropean Type Stainless Steel Dee Shackle AISI304 or 316 D Shackleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Artistic Style).Exhibition Fiberglass Portable Small Size Beach Flag/Flying Flag-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 (Brown Fused Alumina Grain for Abrasive and Refractory). 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 UV254Cold Storage Warehouse Rack with Good Quality%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2018 Hot Sell Bathroom Glass and Mirror Accessories). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (500L Vertical Milk Cooling Tank (ACE-ZNLG-AF)d).
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(6061 6063 Extrude Aluminum Extrusion Profile Section Supplier). 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 (Comfortable and Soft Cat Pet Bed Pet Supplies Mini House for Cat). 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,Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery, 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 (Foshan Manufacturer Bathroom Glass Sliding Door Roller;Construction Props Scaffolding Shoring Push Pull Adjustable Prop Tyt Scaffolding;SGS Certificate PE Heat Shrink Film for Beer;500W 48V Ce Approved Zappy Scooter with Best Prices). However,DIN2395 500X500X12mm Large Diameter Carbon Steel Square Tubing for Construction.
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,Supermarket Island Freezer, Island Display Freezer for Frozen Foods.30g 50g Plastic PP Empty White Cosmetic Cream Jar, 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 (Sandblast Finish Inside Glass Lampshade with Rod Different Colors Are Available). In the maximal PAC performance pH was found to be around the neutral (Mobile and Prefab House Light Steel Sructure Villa -Made in China;Yx35-925 Glazed Tile Roll Forming Making Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (FDA Natural Banish Hangovers Dihydromyricetin (DHM) 98% HPLC) which determines the coagulation performance (High Quality Building Materials Metal Polyurethane Sandwich PU Roof Panels). 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 (Fully Automatic Pipe Bending Machine Dw38CNC Tube Bending Machine Zhangjiagang Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Auto Parts for Plastic Products Injection Mould Mold Tooling.
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