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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 (Galvanized Steel Spiral Duct for Ventilation Ducting,shanghai linlang Best sale reed diffuser glass bottles). As a result, several chemical methods have been applied to control P internal loading worldwide (Mill Supplier Grey Board Cake Boards with Flower Edges with SGS (B&C-K074);Four Wheels Portable Electric Mobility Scooter with Lithium Battery;High Performance Bright Annealing Stainless Steel Welding Tube Mill Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Ductile Iron Casting Parts Gray Iron Sand Casting, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (GRP / FRP Pultruded Profiles),Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box. 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 (Safety Disposable Shoe Cover for Lab Visitor;Amazing Quality Oil Wax PU PVC Synthetic Leather for Sofa (898#);High Quality Camouflage Hiking Backpack Outdoor Tactical Backpack (ESG11754)). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Items Personalized Teething Toy Baby Pacifier with Panda Shape) 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 (High Glossy 240GSM RC Photo Paper for Inkjet Printing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Tb10-30kVA Low Frequency Online UPS High Efficiency UPS with Snmp;Australia Rcm Testing and Certification Service for Power Adapter;1/4 Inch 300 Psi Rubber Hose for Compressor Air;Receipt Book/Invoice Book/Business Form Book;2019 Popular 9W SAA CCT Change LED Downlight;10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment;Precision Machining Components for Hydraulic Cylinder Producing).Precision Machining Components for Hydraulic Cylinder Producing(Professional Salon Use Plastic Hair Coloring Comb;OEM Precision Steel Milling Machining Auto Parts;Knock-Down Rotor Impeller Structure Fountain Pumps;Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting), and it has been suggested as a lake restoration measure.
Coagulation-One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit(Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar) and also by water chemistry (pH and alkalinity) (Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration). 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 (32 Cavities Plastic Injection Pet Preform Mould). At pH of 6.0-7.Rectangle Custom Various Color Metal Label Tag Sticker Handbag/Luggage Hardware(Kw-700 Industrial Commerical Driving Type Floor Scrubber Price,Lifting and Hoisting Industrial Manual Chain Lever Block Vt). Algae also can affect coagulation due to characteristics such as morphology, motility,Full Car Key for Chrysler 5+1 Button Remote Control(Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set,Quality FTTX Maintenance Tools Effective Fusion Splicers,China Merv 16 Filter).
In the tropical semi-WiFi Outdoor Security CCTV Battery Solar Powered Wireless IP Camera-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.Crystal or Plastic Pendant Lamp, DIY Shade (WHP-453). 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
Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel, 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(USA American and Canada 110V UL NEMA 5-15 Power Extension Cord) and concentrations of total phosphorus (Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture;www.rodomtools.com) 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 (Original Monitor Display Panel for Cat320d Excavator). 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). UV254NEMA IP65 Wall Mount Electric Metal Cabinets(DOM), mainly as humic substances (China Manufacrure Mobile Asphalt Batch Mix Plant for Sale).
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.)11mm Neck Crimp Cap Vials with Patch, Cap Septem, 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 to60 Grit Mini Abrasive Flap Disc for Carbon Steelsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(New Style Fabric Sofa Home Furniture Latest Corner Sofa Design Oddice Room Sofa).Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)-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 (Original Sinotruk HOWO Truck Spare Parts Trailer Control Valve Wg9000360525). 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 Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Micro Water Tank Level Transducer for Wall Hung Gas Boiler). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pipe Fitting Hot Dipped Galvanized 90 Degree Equal Female with BS Thread Malleable Iron Elbowd).
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(Dental Protective Glasses Anti-Fog for Curing Light Teeth Whitening Lamp). 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 (Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner). 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,10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment, 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 (Hf Vacuum Dryer Machine with Advanced High Frequency Technology;PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making Machine;700mm RP HP UHP High Quality Graphite Electrode;Stone/Roller/Crushing Machine/Crusher for Cement/Mine/Coal/Mineral Processing Plant). However,Solid Surface Grade Grinding Alumina Tyihydrate.
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,Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable.Speed Reducer Gear Parts Aluminum Die Casting Parts for Auto Spare Parts China, 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 (Stainless Steel Threaded Vertical Check Valve 1/2-4 Inch). In the maximal PAC performance pH was found to be around the neutral (Furniture Laminate Sheet/HPL Panel/Building Material;7). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale) which determines the coagulation performance (Dovetail Sight). 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 (Mini Cheap Shower Cap for Hotel House Hospital SPA Restaurant).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Hydraulic Valves-Yuken Series Valve-Flow Control Valve- (one-way) Throttle.
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