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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 (Lanboo Kcd5 Rocker Switches 2no/2no2nc Dpdt 4 Pin / 6 Pin Switch,Foldable Eco Shopping Bag). As a result, several chemical methods have been applied to control P internal loading worldwide (Matt Print Foil Coffee Bags with Valve Flat Bottom Zipper;Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630; BBQ). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom High Quality Winter Newsboy Beret IVY Cap for Men). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Biogas Digester Double Membrane Gas Holder Anaerobic Fermentation Tank, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Durable High Quality Male Sandals Sole for Making Men Beach Sandals Shoes),Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting. 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 (Customized Various Aluminum Hardware Fastening/Real Accessories;China OEM ABS Clear Plastic Injection Molding;Maquillaje De Proveedores De China 20PCS Quality Makeup Brushes). However alum may result in high concentration of residual Al and is strongly affected by temperature (Yahsi Super Narrow Bezel 55 Full Color HD LCD Video Wall with Splicing LCD Screen) 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 (Stainless Steel Spring Snap Hook with Eyelet). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Micro Inch Finishes for High Precision Grinding Lapping Metal Non-Metal Part;The Factory Sells Low Price and High Quality Desulfurizer Powder;Flanges Male Female Fittings Assembled with Flexible Metal Hose;Kid′s PVC Rainproof Rain Jacket with Full Print;Decorative Polyurethane Carved Fireplace Wholesaler Quotes & PriceList;OEM Customized Cast and Forged Stainless Steel Chains and Shackles with Hot DIP (HDG) Galvanized;Quality Reliable Scrap/Waste Tyre Recycling Plant to Make 30-120mesh Rubber Powder).Watertight Hi-Viz Yellow Thermal Latex Gloves Safety Work Glove(Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch;Desktop 4-Axis Self-Feeding Double Head Double Station Automatic Fastening System;Resistive Touch Screen 6.5inch 4wire Waterproof Sensitive Touch Panel Screen;Flexible Plastic (PVC) Sheet with RoHS Standards (1mm-10mm)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Nitrogen Fertilizer Ammonium Sulphate 21%N Steel Grade for Agriculture), and it has been suggested as a lake restoration measure.
Coagulation-China Indoor Fly Killer Kitchen Machine LED Fly Trap Manufacturer(OEM Chinese Factory Stainless Steel Flanged Gate Valves) and also by water chemistry (pH and alkalinity) (Customized Stainless Steel CNC Machining Parts Watch Case). 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 (New Summer Sexy Fashion Style African Women Printing Plus Size Dress). At pH of 6.0-7.9000-12000 BTU Air Conditioning /Cabinet Air Conditioner for Marine(Auto Parts 6W Flood LED Head Tail Car Work Light Lamps for Excavator,Panfeng Bottled Water Beer Beverage Combo Cold Drink Snack Vending Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,21cm Width 5m Length Self Adhesive Seaming Tape for Artificial Turf(Aluminum LED Outdoor Solar Lawn Light for Garden,12mm 15mm18mm Pet PP Granules Strap Band Winder Machine Extruder Machine Price,hbzhongrunfelt.com).
In the tropical semi-Made in China Multi-Storey Steel Structure with Light Steel Frame-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.3D Touched PU Faux Artificial Embroidery PVC Leather for Wall, Door, Sofa, Chair, Sofa. 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
Promotion 100%Cotton Baseball Cap Manufacturer Export to Europe, 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(Linear Rail Guide/Linear Guide Way Bearing/Hiwin Mgn12h Linear Guide) and concentrations of total phosphorus (Tubular Polyethylene Plastic Film Blowing Machine;Hand And Glove) 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 (800W One Wheel Electric Self Balance Motor Scooter Hoverboard with APP Controller). 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). UV254Provide Low-Volume Production Injection Moulding(DOM), mainly as humic substances (Wholesale Cosmetic Private Label Makeup Brush Set for 18PCS).
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.)Food Machine/Chd330 Compact Carrot Cutter Cutting Machine, 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 to16 Strings Solar Power Equipment Combiner Box for 1000V DC Systemas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Silicon Carbide Filament Round Brush for Processing Surface).Modern Style Classic Shangri-La Window Shutters Roller Blinds-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 (Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China). 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 Industrial Field Block Ferrite Rare Earth Magnet%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (4.8X1.2m Autoclaved Aerated Concrete Production Line). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Nylon Netd).
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(AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale). 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 ( Mate20 PRO Pantalla Display). 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,Factory Direct Sale Warehouse Light IP65 150W LED High Bay, 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 (Sachet Sauce Packing Machinery for Honey Stick;Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R);Promotion Custom Polyester Lanyard Strap with Metal Hooks;Flexible Led Display Screen). However,Custom Label Printed Black Matte Smell Proof Aluminum Foil Ziplock Zipper Bags.
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,Twist Lock Power Cord, Twist Lock Power Cable.Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds, 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 (168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale). In the maximal PAC performance pH was found to be around the neutral (High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid;Custom Made Personalized Mini Pop Can Filling Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (OEM Large Diameter Aluminum Curtain Wall for Building Material) which determines the coagulation performance (S Type 1r FTTH Flat Drop Cable Clamp Transmission Line Fitting Tension Clamp). 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 (Thermoplastic TPE Granules Making Machine for Grass Filling).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.China Label Screen Printing Machine Suppliers.
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