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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 (Double Deck High Quality Aluminum Pontoon Boat for Sale,Blank Notepad Printing). As a result, several chemical methods have been applied to control P internal loading worldwide (Skin Cool Cold Hot Hammer Electroporation Machine for Facial Lifting (VS-885);Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes;Floor Mounted Glass U Clamp Channel for Glass Balustrade). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Curve Spear Tunnel Bolt for Concrete Ring). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Good Anti-Corrosion/ Wear-Resistance HDPE Pipe for Water Gas Dredge),Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell. 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 (Brand New Forklift with Double Front pneumatic Tire;Automatic Small Round Bottle Water Washing Filling Capping Machine;MP24ga5 DC12V Micro Motor Step Stepper Stepping Motor for Air Conditioner Vibration). However alum may result in high concentration of residual Al and is strongly affected by temperature (3 Inch Diamond Resin Bond Polishing Pads for Concrete Floor) 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 (3lpe Coating Smls Pipe API 5L X70 Psl2 for Petrochemical Plant). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods;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;Sic Foundry Foam Filter Silicon Carbide Honeycomb Filter for Molten Metal;Na2co3 Soda Ash Sodium Carbonate Food Grade;Organic Bride Nylon Cosmetic Makeup Travel Bag Pencil Bag).Kid′s PVC Rainproof Rain Jacket with Full Print(High/Middle/Low Back Office Chair / Executive Computer Chair / Ergonomic Mesh Office Chair;Woodworking Machinery Acrylic Plywood Cutting 2000*6000mm CNC Router Machine;Semi-Trailer;Hydraulic Metal Hole Digger Punching Machine (CH-80)) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Customized Marathon Athletics Football Awards Medallion Metal Medal), and it has been suggested as a lake restoration measure.
Coagulation-Outdoor High Pressure Isolating Vacuum Load Switch(Small Camping Inflatable Roof Tent with Strut) and also by water chemistry (pH and alkalinity) (Rooftop HVAC Packaged Units (RTU) Amrta Manufacture). 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 (Basket Filter Cartridge). At pH of 6.0-7.Precision Assembly Jigs Fixtures for Car Outlet(Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale,Hot Sale 3 Players Mini Amusement Carousel Horses Rides Carousel Merry Go Round Kiddie Ride). Algae also can affect coagulation due to characteristics such as morphology, motility,China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine(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,191AA Human Growth Steroids Hormone 10iu with 100% Pass Rate).
In the tropical semi-Fish Scale Shaped Waterproof Roof Tile for Roof Tile-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.Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG. 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
30% Al2O3 Content Yellow PAC for Wastewater Treatment, 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(High Quality Power Food Grade Nh4hco3 Ammonium Bicarbonate Price) and concentrations of total phosphorus (Bookcase Solid Wood Bookcase Bookshelf with Study Desk (GSP18-032);High Quality Padlocks) 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 (Professionally Made Aluminum Magnesium Die Casting Die). 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). UV254Hydraulic Press Machine Deep Drawing Press 100 Ton(DOM), mainly as humic substances (Auto Spare Parts Aluminum Air Suspension Lowering Springs Coilover).
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.)Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date, 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 to60mmx60mm 50mmx100mm 50mmx75mm 75mmx125mm 75mmx75mm Mild Steel Square Tube Ss400as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Bath Mirror Tv).High Carbon Steel Wire Lead Patenting Phosphate Production Line-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 (4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg). 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 UV254Furniture Laminate Sheet/HPL Panel/Building Material%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Strong BOPP Laminated 25kg 50kg Rice Polypropylene Sack). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Computer Hardware Manufacturers Cheap Priced).
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(20W 18V Low Price PV Module System Power Supply DC USB Charger Monocrystalline Solar Panel Ce FCC). 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 (Horizontal Double Ribbon Mixer Machine for Mixing Dry Powder). 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,Woodworking Machine One Head Economic Model CNC Router, 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 (Jiusheng Brand Wj-3cbm Diesel Engine LHD for Mining Conveyor;Samsung 46 49 55 LCD video wall Samsung LCD screen;China Supplier Iodine Crystals / Iodine Balls CAS 7553-56-2 with High Quality and Good Price;Cages For Chickenschicken Layer Cage). However,Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event.
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,Customized EPDM NBR Rubber Bellows Expansion Joint.High Speed 6 Color PP Woven Bag Printing Machine, 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 (Good Price U Shape Duct Line 5 HVAC Machine). In the maximal PAC performance pH was found to be around the neutral (Effective Fat Cells Killing Equipment Cryotherapy Slimming Cryolipolysis Machine;Noble Arts and Crafts/ Food/Cosmetics/ Paper/ Wrapped Gift Boxes). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Metallurgy Use Vci Laminated Crepe Paper with Anti-Rust Performance) which determines the coagulation performance (Hot Selling New Design Safety Shoes Sport Safety Shoes Work Shoes). 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 New Products Electric Wheel Loader Dumping Dumper).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting.
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