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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 (High Quality Medical Disposable Pen Type Blood Collection Needle,Automatic Return Ball System Snooker Table B4t5). As a result, several chemical methods have been applied to control P internal loading worldwide (Multifunctional RF/40K Body Vacuum Roller Weight Loss Beauty Salon Cavitation Beauty Equipment;Full Automatically Wp Line Powder Jet Mill Micronizer in Agriculture Field;Professional Super-Automatic Tyre Changer Without Lever). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Plastic PE HDPE LLDPE LDPE Irrigation Water High Speed Pipe Extruder Making Machines). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Aluminum Canopy Roof Spigot Steel Lighting Stage Truss),Farrowing Crate Galvanized Swine Farrowing Crates. 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 (Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer;Exdiibt4 Explosion Proof Type 10kw Power Inverter Built in Low Frequency Transformer;Stainless Steel Sanitary Pipeline Three-Stage Emulsion Mixing Pump). However alum may result in high concentration of residual Al and is strongly affected by temperature (American Double Hung Thermal Break Aluminum Window in China) 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 (Piano Wire Spring with Customzied Specifications with Factory Price). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Best Industrial Coal Fired Steam Boiler Manufacturer in China;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;m.petnbf.com;Monofilament Fishing Tackle Green Nylon Fish Net;Used Fashion Summer Children′s Dress Unsorted).Double Sided Tape 1/2 Inch 10 Feet, Transparent Acrylic Double-Sided Tape(Longboard or Skateboard Ball Bearings 608zz 608-2RS;High Speed Automatic Facial Tissue Paper Middle Bag Packing Production Line;Household Energy Storage;1000kg/Day Ice Making Machines Custom Ice Cube Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (CNC OEM ODM Customized Car Housing Parts Machining Parts), and it has been suggested as a lake restoration measure.
Coagulation-Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog(Custom Full Color Printing PP Table Mat Plastic Mat for Kitchen) and also by water chemistry (pH and alkalinity) (Sports Bra Shock-Proof Gathering Stereotypes Bra). 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 (Cheap Baseball Caps). At pH of 6.0-7.High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire(2000W 10mm Stainless Steel Mild Steel Fiber Laser Cutting Machine Price,Stainless Steel Mesh Screen Automatic Self-Cleaning Filter). Algae also can affect coagulation due to characteristics such as morphology, motility,Health Food Krill Oil Softgel for Antioxidation(Hot Sale 250ml Green Dorica Glass Olive Oil Bottle,7,Pvc Gypsum Ceiling Machine).
In the tropical semi-Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe-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.Custom Sport Event Antique Brass Plated Lanyard Available Medal. 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
Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker, 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(Round Vibrating Separator Machine - Round Vibratory Sieve) and concentrations of total phosphorus (600ml Travel Sports Bicycle Water Bottle (HBT-037);Injection Plastic Mould for PVC ABS Plastic Industrial Tool Parts) 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 (Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014)). 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). UV2544 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale(DOM), mainly as humic substances (Stainess Steel Handheld Type Pedb-400A Fiber Laser Marking Coding Machine Systems).
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.)Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra, 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 toLong Range UHF RFID Animal Ear Tag for Animal Managementas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Injection Mould Design and Prototype From China).Factory Manufacture Clear and Brown BOPP Packaging Tape-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 ( Delphi). 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 UV2542019 New Product 12mm Mini Short Metal Push Button Switch%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Combination Lock Protect Weed Smoking Accessories in Black or Customization Hot Sale Bag Backpack). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Unscented Tealight Candled).
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(Plywood for Packing Furniture 10-25mm Plywood Price). 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 (106cm TV Background Decorative Wallpaper China Design). 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,Ae Bifacial Solar PV Panel 270W Poly German Quality, 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 (Prefabricated Metal Frame Roof Construction Light Steel Structures;Black High Quality Man Hoody Fitness Hoodie Supplier Pullover Hoodies;Divan Modern Sofa Set U Shape Leather Sofa with Acoustics;Electrical Insulation Base Film). However,High Quality Virgin PMMA 3mm Clear Cast Acrylic Sheet Price.
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,LED Display Fixed Co Gas Monitor Toxic Gases Analyzing.New Product Ideas Wooden Musical Jewelry Storage Box, 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 (Original OTG Mobile Phone Micro-USB to USB-C Gender Adapter for Samsung S10). In the maximal PAC performance pH was found to be around the neutral (Bathroom Glass Door 90 Degree Wall to Glass Zinc Alloy/Stainless Steel Shower Hinge;Semi-Automatic LCD IC PCB Cof Soldering Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Bottle Caps) which determines the coagulation performance (1325 CO2 Paper Acrylic 180W Laser Engraving Cutting Machine). 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 (Multi Function Coffee Capsule Filling Sealing Machine for Espresso/K Cup/Dolce Gusto Vfs-12c).
PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material, charge and density, factors that influence directly in flock sedimentation.Surgical Instrument LED Shadowless Operation Lamp(Automatic Tomato Paste Chilli Sauce Milk Liquid Filling Sealing Food Packing Machine;Remote Lighting Controls Outside Lights Controller LC-6p13). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition). Extracellular and surface-Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm(Drill Collar,Customized Sand Casting Brake Wheel Hub for Trailer and Truck). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Manufacturer Automatic Pet Bottle Water Filling Machine Tomato Ketchup Packing Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (Kitchenware BBQ Grill Mat Toaster Oven Liner for Bakeware).OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag(Ceramic Coil 0.5ml Cartridges Disposable Cbd Vape Pen), particularly humic susbtances. Humic substances are highly negatively charged (NiMH Haaa 800mAh 12V Ni-MH Battery Pack with CB), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Aminoplus 100% Water Soluble Fertilizer AAA45-P-Ncl Animal Source Amino Acid). Maximal UV254removal was observed to be found around pH 6.0 (Digital Printing Pillow for Sofa with Metallic Printing). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Androst 3 5 Dien 7 17 Dione Raw Steroid Powders Fat Burning Prohormones CAS 1420-49-1).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun.
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