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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 (Brand New Forklift with Double Front pneumatic Tire,Water Floating Mat/Soft Foam Swimming Pool Floating Mats). As a result, several chemical methods have been applied to control P internal loading worldwide (Automatic Small Round Bottle Water Washing Filling Capping Machine;MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration;3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Tempered/Toughened Glass/Window/Shower Door Float Glass (T-TP), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (5 Gallon Pc Bottle Blowing Machine Wholesaler Quotes & PriceList),3-Axle 30mt LPG Haulage Truck Trailer Depot Gas Transportation Tanker. 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 (White/Gray Colors U-PVC Water Supply Pipe for Plumbing System;Hot Sales Good Softness Red PE Protective Film Surface Protection for Color Steel Plate;Full Automatic System Swing Cylinder Screen Printing Machine for Enamel). However alum may result in high concentration of residual Al and is strongly affected by temperature (Na2co3 Soda Ash Sodium Carbonate Food Grade) 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 (Blue Hollow Composite Decking Board). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag;High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair;Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine;Hydraulic Metal Hole Digger Punching Machine (CH-80);Black Office Tote Handbag for Young Ladies Women Elegant Bag;Factory Customized Marathon Athletics Football Awards Medallion Metal Medal;Small Camping Inflatable Roof Tent with Strut).Best Factory Price Metallic Honor Medal with Neck Ribbon(Rooftop HVAC Packaged Units (RTU) Amrta Manufacture;Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale;Personal Cnc Milling Machine;Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Esavior 30W All in One Solar LED Light Street Light Motion Sensor Energy Saving Outdoor Light), and it has been suggested as a lake restoration measure.
Coagulation-Filter Press Machine for Sand Washer Sludge Dewatering Working Site in China(3-Ply Copper/Stainless Steel Cookware Set with Hammer Patten) and also by water chemistry (pH and alkalinity) ( Grass Cutting Machine). 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 (New Design Fake Leather Gift Jewelry Packaging Case Box for Bracelet). At pH of 6.0-7.Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype(Honglang New Wood Burning Stove Fan of 4 Blades (HL-800C1),High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price). Algae also can affect coagulation due to characteristics such as morphology, motility,Poultry Farming Automatic Chicken Feeding Pan System(Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032),ANSI B16.5 Stainless Steel SS316 Forging Blind Flange,high quality equal angle and unequal angle supplier).
In the tropical semi-Water Resistant Rubber Gasket for Industry-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.Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer. 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
PVC Gas Hose, LPG Hose Best Choice for Home Use, 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(Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover) and concentrations of total phosphorus (Interior Decorative Soundproof Acoustic Foam Sponge Panel (AFSYF50-5);Auto Water Bottle Shrink Film Wrapping Packaging Packing Machinery Machine) 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 (60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400). 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). UV254Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan(DOM), mainly as humic substances (Ceramic Floor Tile Wear Resistant Tile Non-Slip Floor Tile).
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.)Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress, 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 to CNC Milling Machine (VMC850)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(24v 10ah Battery Charger).Best Polystyrene Sandwich Board Manufacturer-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 (Black Acrylic Steam Shower Room Cabin with 6mm Tempered Glass). 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 UV254Outdoor WPC Wood Plastic Composite Fence Board with High Quality%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (860-960MHz Rfif UHF Price Label for Jewelry Programmable RFID Tag). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (30t Overhead Crane /New Mobile Tower Container Crane for Hot Sale Chinad).
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(Samsung 46 49 55 LCD video wall Samsung LCD screen). 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 (China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price). 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,Full Automatic Chocolate Holding Tank with Water Jacket, 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 (Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes;Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance;Hot New Products Electric Wheel Loader Dumping Dumper;High Performance Single Acting Pneumatic Actuator Ce). However,Professional Supplier of Hot Rolled Steel U Channel.
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,22mm 2no2nc Metal on off Start Button Power Push Button Switch.Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack, 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 (Mini Unisex Multifunction Key Wallet Coin Purse with Magnetic Buckle). In the maximal PAC performance pH was found to be around the neutral ( Commercial Trampoline Park for Sale;Personal Operation Rebar Wire Tier Tools for Building). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Smoking Ceramic Pods Empty Cartridge Start Kit) which determines the coagulation performance (Customized Stone Mantel Surround White Marble Fireplace (GSMF-173)). 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 (Most Popular Android Satellite Receiver Android DVB S2 Cccam).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag.
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