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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 (Aluminum Mold Making Die Casting Motorcycle Spare Parts,Hdpe Sheet Extruding Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Plastic PVC/WPC Granulator Die Face Cutter Extruder Machine;Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose;Stage LED Bar 54PCS*3W RGBW DJ Disco Stage Lights). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Air Rubber Hose Factory OEM/ODM Product),Low Price Promotional Concrete Cement Mortar Plaster Pump Machine. 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 (Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring;CNC Machining Milling Aluminum Bike Components;Dny Automatic Stainless Steel 304 Belt Filter Press). However alum may result in high concentration of residual Al and is strongly affected by temperature (Hot Sale Bamboo Toothbrush in Flate Simple Design) 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 (Copper Press Fitting). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Honed St52 Piston Tube for Hydrau; IC Cylinder;EV850m CNC Machine High Precision Vertical Machining Centers Price;Stainless Steel Welded Wire Mesh BBQ Grill Grate/Mesh for Cooking;NEMA 14 High Frequency Low Noise Stepper Motor (35SHD0001-15);Cnc Control;Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa;Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers).18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display( Cosmetic Fluorescent Pigment Powder Manufacturer;Excellent Quality Wooden Cosmetic Display Counter for Retail Store;Chemical Etching Stainless Steel Flat Heating Element Film for Electronic Cigarette Heating Wire;Cheap Customized PVC Rubber Book Mark Clips with Any Logo Design for Promotion/Advertising (XF-BM10-)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality Blue/Yellow/Green/Brown/Grey Agate Luxury Stone Slabs for Interior Decoration), and it has been suggested as a lake restoration measure.
Coagulation-34*25cm Office File Pocket Felt A4 Document Bag(DIN976 Grade 4.8 8.8 10.9 12.9 Carbon Steel Zinc Plated HDG Threaded Rods Bar) and also by water chemistry (pH and alkalinity) (Industrial and Commercial Screw Compressor Water Chiller). 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 (Customized Printed PP Plastic File Folder with Zipper). At pH of 6.0-7.Hex Washer Heaf Self-Drilling Screw with Steel and Rubber Washer(Qbeka Anti-Aging Serum Qbeka Copper Peptide Tendering Serum Anti Wrinkle Serum Face Serum,Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097)). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Quality Square Mini Takoyaki Grill Pan with Helper Handle(1325 High Quality Steel Aluminum Metal Plasma Cutting Machine,Latest Design House Sandal Disposable Hotel Slipper,Meat Pot Camping Casserole).
In the tropical semi-Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern-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.High Drying Efficiency Wood Sawdust Dryer for Sale. 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
Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy, 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(1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler) and concentrations of total phosphorus (Wns Gas Oil Fired Boiler Hot Water Heating System;Double Glass Washer Machine) 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 (3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist). 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). UV254Wood Grain Vinyl Films/Self Adhesive Decorative Paper for Furniture(DOM), mainly as humic substances (Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken).
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.)Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant, 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 to5 Inch Diamond Protected Teeth Blades for Cutting Graniteas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(5.5 Cbm Yield Self Loading Concrete Truck for Sale).Jelly 3 Industrial Camera for High Speed Vehicle Plate Image Capture Mu3s640m/C (SGYYO)-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 (Water Heater Single Head Shrinking Machine). 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 UV254Best Price Aluminium Sulphate for Water Treatment%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Co-Extrusion Extruder Single Screw Auxiliary). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Gray Felt Fabricd).
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(Immersion Gold 94V0 Circuit Board Assembly Saving Energy Electrical PCB). 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 (Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker). 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,Large Format Automatic Cloth / Textile / Leather / Tailoring Laser Cutting Machine 1630, 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 (Clear Plastic PVC Window Cmky Full Color Printing Box;Good Quality Brow Pencil Pencil Private Label Wholesale;Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic;163 Oled High Quality Supplier). However,Sinbeda LCD Display for Sony Xperia Z1 Touch Screen.
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,ASTM AISI 4140 42CrMo4 1045 S20 Cold Drawn Steel Round Bar.Packaging Tea Tin Box Blank Round Tin Cans Small Empty Coffee Food Grade Mini Sealed Gift Boxes, 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 (Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow). In the maximal PAC performance pH was found to be around the neutral (Jingsun off Grid 100kw Solar Power System for Project;RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Very Cute Baby Gift Packing Shopping Carrier Paper Bag) which determines the coagulation performance (www.jprmodel.com). 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 ( Cookware Set with Hammer Pattern).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Disposable Double Ended Cleaning Brushes for Endoscope Port Hole.
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