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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 (2.0mm Pitch Pin Header SMT Type R Sereis Single Row Dual Housing,Aminoguanidine Nitrate). As a result, several chemical methods have been applied to control P internal loading worldwide (Steel Structure Welding Steel Structure Metal Building;High Temperature Fireproof PU Coated Silica Fabric;Polypropylene Strapping Band Production Line/PP Strap Making Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3 Way Manual Staple Gun with Staples for Hand Tools). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Grade 10A Free Sample Mink Raw Virgin Brazilian Chinese Girls Human Hair in Mozambique, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Laser Cutting Equipment),Stable Quality Vacuum Heat Treatment Atmosphere Sintering Furnace. 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 (Golf Practice Nets and Cage/Professional Training Golf Net;Automatic Plastic and Glass Bottle Inductor Sealing Machine;Surgical Instrument LED Shadowless Operation Lamp). However alum may result in high concentration of residual Al and is strongly affected by temperature (Stray Inductance 210~2100uh Frame Core Current-Compensated Common Mode Choke Coils) 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 (Customized Precision CNC Milling Parts with Metal). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Cbhs-F32 Hydraulic Oil Transfer Gear Pump for Fuel Forklift;Precision Oscillating Multitool Sharp Cutting Blade for Wood;Aluminum Alloy Die Casting for Mechanical Part (STK-14-AL0047);1300*700*700mm Vertical CNC Milling Machine CNC Lathe CNC Machine Center CNC Machine Tool;Different Color 3D Brick Effect PE Foam Wallpaper for Decoration;20L Semi Automatic China Bottle Pet Blower;professional Manufacturer One Arm Motorized Multifunction for Medical Products).Linear Block Bearing Abba Brh25b Brh20b Brh15b Brh30b Brh35b Brh45b CNC Linear Carriage(Banana Slicer Cutter Perfect for Fruit Salad Yellow Banana Cutting;Electric Baking Heat Preservation Deck Oven Manufacture;Sentek Rolling Ball Magnetic Contacts Door Sensor;Electric Vibrating Massage Cream Jar for Cosmetic Packaging) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Gym Fitness Equipment EPDM Surface Gym Rubber Flooring Mat/Rubber Flooring with 500*5000/1000*1000mm), and it has been suggested as a lake restoration measure.
Coagulation-Construction Equipment Full Automatic Concrete Block Making Machine(High Precision Injection Molding Plastic Parts in China (STK-PL-1055)) and also by water chemistry (pH and alkalinity) (Venlo Polycarbonate Covering Material Greenhouse on Sale). 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 (Luxury Bamboo Fiber Cotton Pillowcase with Polyester Filling Pillows (YFP050)). At pH of 6.0-7.Customized Sheet Metal Products, Stamping Parts, Welding Parts(Rubber Recycling Machine Powder Tire Derived Fuel Machine Small Tyre Recycling Plants,Metallic Paint Solid Aluminum Cladding Panels for Roof Covering/ Ceiling). Algae also can affect coagulation due to characteristics such as morphology, motility,Cartoon Design Decorative PVC Sheet for Wall Panel Moulding(VGA multi screen video wall LCD video wall panel with wall screen matrix,Customized Dust Filter Cartridge Price for Industrial Welding Fume,Good Price Raycus/Ipg 1325 Size Fiber Laser Cutter Machine).
In the tropical semi-4 Fibers Wall-Mounted FTTH Distribution Box-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.4-20mA Signal Steam Directional Flow Pneumatic Control Valve. 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
Non Woven Wheel for Stainless Steel Polishing and Grinding, 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 Sheet Metal Laser Cut/Aluminum Sheet Metal Laser Cutting) and concentrations of total phosphorus (Light Blue Color Glass Drink Bottle for Beer;Custom Printed Laminated Material Plastic Side Gusset 1 Kg Coffee Bean Packaging Bag with Air Valve) 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 (3.5mm). 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). UV25430cm Round Clear Plastic Pot Plant Trolley(DOM), mainly as humic substances (Eye Cream Tube Function Eye Cream Container Ceramics Eye Cream).
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.)Decorative Waterproof Fireproof Heat Resistant HPL High Pressure Compact Phenolic Laminate Board, 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 to500ml Amber Pharmaceutical Glass Bottle Medicine Bottle Chemical Bottle Pesticide Bottleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Super Type Lm6uu Linear Bushing Ball Bearing for SMT IC PCB Machine Linear Bearing).Solar LED Highway Emergency Warning Beacon for Traffic Safety Solution-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 (Lower Price Luxury Waterproof Spc Vinyl Floor Tile). 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 UV254AL926C Tractor Wheel Loader with Extreme Long Arm 4500mm Dumping Height for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Chrome Steel Cam Follower CF4 for Machine Parts). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Petg Plastic Sheetsd).
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(Galvanized Material Metal Workshop and Warehouse Peb Light Steel Structure). 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 (Sle4442 hotel key card PVC blank contact RFID card). 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,Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale, 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 (Solar Panel Mounting Solutions Mounting Bracket Mounting Kit Mounting System;800kgs Steel Wire Rope Hand Winch for Lifting;10m3 Mobile LPG Filling Skid Station for Gas Cylinders;2019 High Quality Precision Customization Stainless Steel Brass Gear Parts of Enpu). However,PCB Mounting Shielded Modular Jack Ethernet RJ45 Connector.
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,ODM Customized Black Anodized AISI304 Stainless Steel CNC Machined 12mm Axle Washer (S-120).Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making, 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 (Woodworking Machine One Head Economic Model CNC Router). In the maximal PAC performance pH was found to be around the neutral (Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt;100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Hanna Good Quality Door Spray Paint Machine) which determines the coagulation performance (Car Roof Tent With Awning). 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 (Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Professional Manufacturer NPT Thread Dustproof Nylon Cable Gland / Plastic Cable Gland.
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