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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 (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer,Automatic Nail Making Machine). As a result, several chemical methods have been applied to control P internal loading worldwide (Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer;Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump;American Double Hung Thermal Break Aluminum Window in China). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Industrial Coal Fired Steam Boiler Manufacturer in China). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Corn Starch Foam Biodegradable Frozen Food Packaging Tray, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Reinforced Decorative Pattern. Aluminum Foil Adhesive Tape),Highway Outdoor Road Integrated Solar LED Street Light Price List. 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 (7 Colorful 240 Degree Wide Lens Mini Speaker Smart WiFi Camera of Night Light Wc001y13;18X18 Asian Black Iron Square Tube/Black Square Steel Pipe Seamless;Luxury Modern Bathroom Furniture Sanitary Ware Solid Surface Basin). However alum may result in high concentration of residual Al and is strongly affected by temperature (Monofilament Fishing Tackle Green Nylon Fish Net) 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 (Usb C Otg Cable). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Used Fashion Summer Children′s Dress Unsorted;Longboard or Skateboard Ball Bearings 608zz 608-2RS;High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line;1000kg/Day Ice Making Machines Custom Ice Cube Machine;12m Bus Front Axle No-Independent Air Suspension System;CNC OEM ODM Customized Car Housing Parts Machining Parts;Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen).Commercial Mix Flavor Ice Cream Machine Yogurt Soft / Hard R410A 3 Flavor 110V(Sports Bra Shock-Proof Gathering Stereotypes Bra;2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price;30g Oval Shape Acrylic Cosmetic Cream Jar Plastic Packaging Jar;Stainless Steel Mesh Screen Automatic Self-Cleaning Filter) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Sale 250ml Green Dorica Glass Olive Oil Bottle), and it has been suggested as a lake restoration measure.
Coagulation-Integrated Circuit Printed Circuit Board China Trusted PCB Manufacturer(7) and also by water chemistry (pH and alkalinity) (Factory Stocked 500ml Double Wall Plastic Glitter Water Bottle Diamond Lid Insert Layer). 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 (Siemens Solenoid Valve). At pH of 6.0-7.Wholesale Comfortable Men′s Winter Leather Snow Boots(High Quality Cheap Custom Small Kids Exercise Outdoor Playground with Slide,Round Vibrating Separator Machine - Round Vibratory Sieve). Algae also can affect coagulation due to characteristics such as morphology, motility,Tecjet Cloth Printer Printing Machine 6090 DTG Printer(600ml Travel Sports Bicycle Water Bottle (HBT-037),Shielded Mini Ball Bearings with Anti-Rusty Stainless Steel Smr106zz,Best Selling Chocolate Preserved Flower Gift Round Box).
In the tropical semi-Hot Sale Instax Mini Camera Korea Style Photo Album-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.Outdoor LED Street Pole Advertising Business Double Sided LED Signs. 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
Patened Design Large Mich Indoor Trampoline Park for Kids, 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(Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems) and concentrations of total phosphorus (Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid;One Side Combination Sharpening Stone / Whetstone) 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 (Long Range UHF RFID Animal Ear Tag for Animal Management). 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). UV254EV850m CNC Machine High Precision Vertical Machining Centers Price(DOM), mainly as humic substances (Outdoor Self Adhesive Reflective Vinyl Plastic Sheet Traffic Tape).
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.)10kv Xple Heat Ahrinkable 1-Core Outdoor Termination Kit (Section 500~630 mm^2), 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 toMeat Processing Cooling Flake Ice Making Machine (Shanghai Factory)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(fast charging for iPhone 8/8 PLUS/X/XS/XS Max).Trisun Mechanical Seal Spare Parts Wave Spring-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 (Customized Precision CNC Milling Aluminium Parts for Press Die Mould). 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 UV254Fiberglass Water Park Spray Playground Equipment for Sale%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (China Best Price Plain MDF Board/White Melamine MDF 6mm 12mm 18mm). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (1300 Duplex Automatic Slitting and Rewinding Machine for BOPP Filmd).
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(Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies). 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 (Divan Modern Sofa Set U Shape Leather Sofa with Acoustics). 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,Swivel Hook Auto Engine Valve Spring Motor Spring, 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 (Semi-Automatic LCD IC PCB Cof Soldering Machine; Bottle Caps;Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c;UL Dlc 10000lm 100W E40 LED Retrofit Kit with 5 Years Warranty Meanwell Driver). However,Modern Living Room Wood Frame Genuine Bonded Leather Chesterfield Sofa.
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,Germany Imported IPL Xenon Flash Lamp/IPL Lamp/Xenon Lamp.High Quality ABS Nylon Stainless Steel Bathroom Shower Chairs for Elderly, 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 (Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine). In the maximal PAC performance pH was found to be around the neutral (Remote Lighting Controls Outside Lights Controller LC-6p13;Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Customized Sand Casting Brake Wheel Hub for Trailer and Truck) which determines the coagulation performance (Men Toiletry Bag Manufacturers). 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 (Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing Machine).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Lightweight New Design Girl Fashion Bags Children School Backpack.
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