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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 (Portable Medical Ozone Therapy Unit Zamt-80 on Sale,Rain Gutters Roll Former Downspout Forming Machine Manufacturer). As a result, several chemical methods have been applied to control P internal loading worldwide (Wet Dry Diamond Polishing Pad Concrete Polishing Resin Pads; stainless steel 316/304;High Precision CNC Turning Milling with Good Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Polyester/PP Short Fiber Needle Punched Non Woven Geotextile Fabric). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Direct Steering Gear DC Motor with Low-Speed High Torque Spare Parts, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Glass Jam Jars),1630 Auto Feeding CO2 Laser Cutting Machine for Textile, Fabric, Cloth, Leather. 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 (OEM Basketball Sport Longer Elastic Leg Guard Shin Guard;High Purity Granulated Sodium Chloride for Deicing Road Salt;Galvanized Wire Rope Sling with Eyes at Both Ends). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ampoule Sealer Machine Hydrogen Oxygen Gas Generator) 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 (TP304L/Tp316L Seamless Stainless Steel Tube Supplier Galvanized Steel Pipe Manufacturer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (6.5HP Carrier 06dr241 Cold Room Compressor Refrigeration Unit for Fresh Storage;C37 7W E26 Indoor Lighting LED Lamp Energy Saving Bulb;Fashion Sports Woven Wristband with Print Logo;High Quality Water Supply Pn10 PVC UPVC Pressure Tube Pipes;32A 7kw EV Charger Unit Charging Station for Electric Cars;925 Fashion Silver Heart Earrings Stud Simple for Sale;Fiberglass Reinforced Plastic Composite FRP Grating Pultruded).Export Quality Straight Dried Instant Flavor Kelp Seaweed Noodle(Aluminium/Aluminum Customized High Quality CNC Machining Extruded Sheet with Anodization;ASTM E1474 Cone Calorimeter Heat Release Rate Flammability Testing Equipment;Coffee Pouch;Car Backup Lights 2835 SMD T20 7440 LED Turn Lights for Motorcycles) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Construction Structure Steel Shot Blasting Cleaning Machine), and it has been suggested as a lake restoration measure.
Coagulation-Custom Aluminum Die Casting Parts for Medical Equipment(Electronic Lab Aging Test Chamber UV Light Tester with 340 a B Lamp) and also by water chemistry (pH and alkalinity) (High Efficiency 5 in 1 Mug Heat Press Machine). 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 (Laser Cutting Device). At pH of 6.0-7.High Quality Asphalt Waterproof Emulsion Bitumen Emulsion Coating(3core 95mm 185mm XLPE Cable Armored Electric Cable, /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR). Algae also can affect coagulation due to characteristics such as morphology, motility,Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine(Exquisite Workmanship Rubber Shoe Vulcanizing Autoclave with Electric Heating,RF Wrinkle Removal IPL Hair Removal Skin Rejuvenation Beauty Salon Equipment with Filter,Outdoor Coat).
In the tropical semi-High Quality 200W IP66 China LED Flood Light-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.Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift. 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
20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC, 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(Stainless Steel Waterproof Anti-Explosion Ik10 IP65 LED Linear Tube Light) and concentrations of total phosphorus (Small SMT Reflow Soldering Ovens for LED PCBA (A6);China Air Freight Agent To Myanmar Burma) 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 (Custom Printing Polyester National Countryvinyl Nobori American Banner Flag). 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). UV254Single Double Multilayer PCB with High Precision Custom Printed Circuit Boards(DOM), mainly as humic substances (Hot Sale HD MD980asd Wireless Intraoral Camera with SD Card Storage).
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.)High Quality Polyurethane Adhesive for Scrap Sponge, 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 toHigh Quality 7.5W Fast Wireless Charging Pad for Smart Phonesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Flame Redartant/Steel Tape Armored/XLPE Insulated Electric Power Cable).Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine-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 (Large Capacity Sinotruk HOWO 6X4 371HP Tractor Truck). 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 UV254Multi Span Venlo Type Agriculture Production Glass Greenhouse%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (OEM 15t Conveyor Cast Iron Simplex Duplex Triplex Chain Sprocket Gear). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Custom Gift Box Factory OEM/ODM Productsd).
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(Protective Covers /Surplus Groundwater Storage Lagoons and Barren and Processing Pond Liner). 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 (Small Mini Homemade Grain Corn Maize Powder Feed Grinding Mill). 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,Video Tripods Monopod Self Aluminum Camera Tripod, 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 (8 Seaters Solid Surface Quartz Dining Table and Chair;Plastic Traveling Pet Crate Dog and Cat with Wheels and Handle Travel Cage;Construction Product Metal Steel Galvanized Flooring Deck for Wholesaler;Colorful Sequin Tassel Lace Polyester Fabric 134). However,Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5).
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,0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag.Modern Ladies Clothes Shop Design for Clothing Store Display, 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 (AC 110V- AC 230V 50Hz Power Supply Sound Box with 15inch). In the maximal PAC performance pH was found to be around the neutral (Jumbo Roll Two/Double Sided Coated Solvent Base Tissue Tape (DTS10G-11);Perfect Protection for Guideways of Stainless Steel Telescopic Way). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Green&Health High Quality Modular Cold Room Storage for Fruits and Vegetable) which determines the coagulation performance ((SZ-WSL326) High Quality 6 Seats Partition Vice Cabinet Office Staff Workstation). 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 (The Full Thread Bolt with Square Shape Head From Guangzhou).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy.
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