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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 (Hydraulic Metal Hole Digger Punching Machine (CH-80),Commercial Greenhouse Cost Manufacturers Cheap Price). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Customized Marathon Athletics Football Awards Medallion Metal Medal;Small Camping Inflatable Roof Tent with Strut;Rooftop HVAC Packaged Units (RTU) Amrta Manufacture). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Rechargeable Battery Powered Indoor WiFi Camera with Custom APP, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fishing Rod Tube),Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet. 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 (Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride;Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light;3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten). However alum may result in high concentration of residual Al and is strongly affected by temperature ( Grass Cutting 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 (Laser Marking Control Board). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1);High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price;Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032);ANSI B16.5 Stainless Steel SS316 Forging Blind Flange;Sanitary Stainless Steel Food Grade Pneumatic Actuator Wafer Butterfly Valve;Sintered Rare Earth NdFeB Magnetic Permanent Neodymium Block Magnet for Motor;Professionally Made Aluminum Magnesium Die Casting Die).Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine(Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover;Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5);High Quality Fridge Mini Refrigerator Small Size;China Cup Set Handmade Coffee Cup and Saucer Set) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (NEMA IP65 Wall Mount Electric Metal Cabinets), and it has been suggested as a lake restoration measure.
Coagulation-Professional Palm Handheld Veterinary Ultrasound Diagnostic System(60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400) and also by water chemistry (pH and alkalinity) (Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile). 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 (150W Dimming LED Street Light for Solar Street Light). At pH of 6.0-7.Custom Logo Small Beer Mug One Ounce Mini Stein Glass(Hight Quantity Micropore Tfc-3012-300gpd RO Membrane,4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). Algae also can affect coagulation due to characteristics such as morphology, motility,PVC Coated Galvanized 12 Guage Iron Baling Wire(Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack, CNC Milling Machine (VMC850),Common Wire Automatic Nail Making Machine Price for Sale).
In the tropical semi-Kh CNC Plasma Cutting Machine 1530 CNC Controller-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.High Quality Anti-UV Artificial Garden Grass Carpet. 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
Sw Type BOPP Packaging Adhesive Tape Coating Machine, 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(Black Acrylic Steam Shower Room Cabin with 6mm Tempered Glass) and concentrations of total phosphorus (860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag;Security Camera) 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 (China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price). 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). UV25419mm Fancy Plywood for Door Use and Whole House Decorative(DOM), mainly as humic substances (Good Price U Shape Duct Line 5 HVAC Machine).
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.)Left Door Lock Set Key for Land Rover Discovery 4 Auto Modified Car Door Lock Cylinder, 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 toHot New Products Electric Wheel Loader Dumping Dumperas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Variable Frequency Drive with High Performance).High Quality M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos-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 (Personal Operation Rebar Wire Tier Tools for Building). 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 UV254Customized Logo Low Price Fashion Wholesale PVC Silicone Wristband for Merry Christmas Gift%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Smoking Ceramic Pods Empty Cartridge Start Kit). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Dimmable Student Light High Quality 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(100W 120W 150W COB LED Street Light Housing). 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 (Yhy Heavy Duty Perforated Mesh Used for Crusher Screen Machine). 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,Stainless Steel Expanded Metal Mesh for Industrial, 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 (Cheap Gift Custom Engraved Water Drop Shape Golf Award Trophy (003);Made in China X42-X70 API 5L SSAW Steel Pipe for Oil and Nature Gas;0.35mm Thick 1000mm Width PPGI Solar Roof Painting Galvanized Sheet Metal;Electronics Air Cooler PCB Assembly). However,Mobile Phone LCD Display for iPhone Xr Digi-Top OEM 1: 1 OLED Touch Screen LCD Display.
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,Oversized Canvas Travel Tote Luggage Weekend Duffel Bag.Bi-Directional Brushless DC Electric Motor, 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 (Safety Stimpson Meat Grinder Appliances Kitchen Fast Slicer). In the maximal PAC performance pH was found to be around the neutral (Auto Spare Part New Best Selling Auto Parts Air Filter 17220-Rn0-A00 with Free Sample;Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Promotional Safety Products D160 Hang Reflectors) which determines the coagulation performance (Pipe Fitting Elbow). 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 (Porcelain Custom Logo Ceramic Tiki Cup Mug).
Mini Cargo Elevator, Restaurant Kitchen Used Lift, charge and density, factors that influence directly in flock sedimentation.Modern New Design Red Back Massage Table Pedicure Chair(IC ID Epoxy Tag Entrance Guard Card Key Fob for Elevator Property Management;2kw 24V Textile Sewing Machine Motor with DC Power and Intelligent Control Available). 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 (Aluminum Hard Equipment Gift Flight Case for Guitar). Extracellular and surface-Plastic Valve with The Membrane Heat Welding Machine(App Control Scent Machine,12 Kv Vacuum Circuit Breaker with Embedded Poles/ 12kv Vacuum Switch). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Eco Recycled Kraft Paper Box for Salad and Lunch), which can be one important cause of the increase in coagulant demand in algae-rich waters (C6251 lathe machine specification gap bed lathe machinery universal lathe machine).Manufacturer of Titanium/Alloy Titanium Bolt and Nut for Bicycle Use(Portable for Mobile 120W 24V Automatic Car Key Cutting Machine), particularly humic susbtances. Humic substances are highly negatively charged (Laminated Shopping Bag Suppliers for Sale), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Delivery Cylinder Used in Concrete Pump Truck for Construction). Maximal UV254removal was observed to be found around pH 6.0 (Disposable Medical Instrument of Endoscopic Biopsy Forceps Tips). 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 (Black Shelf Table Storage Basket Rack Kitchen Wire Mesh Cabinet Organiser).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Transformer Silical Gel Breather DIN -42567 Form C.
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