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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 (Fashion Leather Wristband USB Disk 4GB to 32GB,Steel Specification Cold Rolled Strip Coil Made in China). As a result, several chemical methods have been applied to control P internal loading worldwide (Multiple Selection Foldable Fashion Waterproof Travel Toiletry Cosmetic Makeup Bag;Top Quality Model Tqlq Series Combined Paddy Cleaner for Rice Processing Plant;Eco Brava Small Mud Interlock Brick Press Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (7 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Professional Palm Handheld Veterinary Ultrasound Diagnostic System, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (European Classic Sofa),Custom Logo Small Beer Mug One Ounce Mini Stein Glass. 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 (Textile Machine Parts Multiple Pattern Box;Elevator Door Phone Industrial Telephone Knzd-15 for Clean Room with Double Loudspeaker;Accept Customization Perfume Direct with Good Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (AAC Autoclaved Aerated Concrete Brick Making 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 (Straw Planter Basket). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cooking Oil Filters South Africa Cooking Oil Cleaner and Filter;Geekvape Aegis Squonk Tc Kit 100W Wholesale Price E Cigarette;FM Mini Portable Voice Music Amplifier Wired Microphone for Teachers with HiFi Sound;Kindergarten Themes Children Furniture Sets Classroom Adjustable Baby Chair;Interior Design White Custom Kitchen Cabinets Oak Wood;2400 Dpi Resolution Offline CTP Offset Printer;Trailer Part Coupling).PVC Coated Galvanized 12 Guage Iron Baling Wire(Small MOQ Food Grade Glass Bottle Wine Cork Stopper;High Quality Precision Plastic Mold/Mould Insert;China Low Cost CNC 1530 Metal Plasma Cutting Machine for Stainless Steel Iron;Alternator for Toyota 91) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Guard Rail Roll Forming Machine 2.0-4.0mm Thickness), and it has been suggested as a lake restoration measure.
Coagulation-Kh CNC Plasma Cutting Machine 1530 CNC Controller(China Genuine Leather White Color Safety Shoes) and also by water chemistry (pH and alkalinity) (HS20-600 Shipping Lifting Device Customized Hydraulic Station). 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 (LCD Display Handhold Under Vehicle Security Car Search Inspection DVR Camera SPV-918). At pH of 6.0-7.High Quality Anti-UV Artificial Garden Grass Carpet(China Supplier Customized Polish Storage Wall Mounted Wine Rack,Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use). Algae also can affect coagulation due to characteristics such as morphology, motility,Sw Type BOPP Packaging Adhesive Tape Coating Machine(Zp9 Punches and Dies Rotary Tablet Press for USA Market,Professional Manufacture C Frame Power Oprated 10 Ton Yq41 Hydraulic Punch Press,Chinese World Combine Harvester).
In the tropical semi-19mm Fancy Plywood for Door Use and Whole House Decorative-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.Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder. 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
High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos, 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(Gi Galvanized Iron Sheet Hot Dipped Galvanized Steel Sheet Galvanized Sheet Metal Plates) and concentrations of total phosphorus (Commercial Promotion White Inflatable Party Tent for Exhibition;Malleable Iron Threaded Pipe Fittings Banded Galvanized Street 45 Elbow) 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 (Ykk Series of Air-Cooled 6kv Medium-Sized High-Voltage Three-Phase Asynchronous Motor). 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). UV254Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift(DOM), mainly as humic substances (Frontlit PVC Flex Banner for Outdoor Advertising).
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.)Stainless Steel Expanded Metal Mesh for Industrial, 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 toKinkai Meat Heat Pump Dryer Machine/ Drying Ovenas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Quick Turn Multilayer Rigid PCB Printed Circuit Board).Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display-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 (Patened Design Large Mich Indoor Trampoline Park for Kids). 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 UV254Oversized Canvas Travel Tote Luggage Weekend Duffel Bag%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Supply High Quality MIFARE® DESFire® EV1 2K/4K/8K RFID White PVC Card). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Customized Food Grade Rectangular Metal Can Christmas Gift Tin Box with Ribbon for Chocolate Candyd).
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(Hot Sale Glass Manual Salt Grinder Pepper Mills/Spice Jars). 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 ( Portable Home Dehumidifier for Whole House). 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,Bi-Directional Brushless DC Electric Motor, 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 (Fiber Laser Marking Machine with Jpt Mopa 120W Laser Source for Cutting Thin Metal;Disposable Rotatable Endoscopic Grasping Net Loop;Composite Suspension Transmission Insulator String with Electrical Power Fitting;Factory Wholesale Barber Shop Shampoo Chair Hair Wash Chair). However,Mini Cargo Elevator, Restaurant Kitchen Used Lift.
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,Modern New Design Red Back Massage Table Pedicure Chair.Plastic Valve with The Membrane Heat Welding Machine, 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 (SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker). In the maximal PAC performance pH was found to be around the neutral (Aluminum DJ Truss for Exhibition Lighting Truss;Biodegradable PLA Film for Food /Fruit Packaging). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Automatic Paver Block Making Machine for Sale) which determines the coagulation performance (Containing Fabric Brighteners China Washing Powder Klin Detergent Powder). 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 (12 Hooks Wood Coffee Mug Holder Rack for Kitchen Storage).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Latest Popular off Road Electric Citycoco 1500W 2018 Scooter.
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