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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 (Tungsten Carbide Stamping Dies /Punching Dies/Metal Stamping Dies,Stainless Steel Decorative Perforated Metal Sheet). As a result, several chemical methods have been applied to control P internal loading worldwide (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)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (New Items Personalized Teething Toy Baby Pacifier with Panda Shape). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Mould Tool Design),Custom Design Stainless Steel Sheet Metal Fabrication Box Cover. 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 (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). However alum may result in high concentration of residual Al and is strongly affected by temperature (Receipt Book/Invoice Book/Business Form Book) 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 (380V 3 Phase Vertical Vibrator Motor for Sieve Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (10.1 LCD Module 1024*600 Optional Touch Panel for Medical Equipment;Precision Machining Components for Hydraulic Cylinder Producing;Professional Salon Use Plastic Hair Coloring Comb;OEM Precision Steel Milling Machining Auto Parts;Thin Film.;Luxury Wedding Collapsible/Folding Paper Packing Gift Box for Gift Packaging;Hot Sale Brass Chrome Metal Dish Toilet Bathroom Fitting).Digital Printing Pillow for Sofa with Metallic Printing(Airtight Preserving Nut Glass Storage Jar Christmas Candy Glass Jar;Cheap Price SGS 304 201 Mirror Etched Stainless Steel for Wall Panel Decoration;2018 Top Tws Earphone True Wireless Stereo Bluetooth 4.2 Noise Cancelling;Kw-700 Industrial Commerical Driving Type Floor Scrubber Price) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Lifting and Hoisting Industrial Manual Chain Lever Block Vt), and it has been suggested as a lake restoration measure.
Coagulation-Micron Circular Stainless Steel Filter Disc(Nylon Kitchen Tools Set Cutlery Set with Stainless Steel Kitchen Set) and also by water chemistry (pH and alkalinity) (Quality FTTX Maintenance Tools Effective Fusion Splicers). 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 (Construction Light Gauge Steel Framing Warehouse Stadium Steel Structure). At pH of 6.0-7.Wholesale Portable Travel Bamboo Tooth Brush Holder(Stainless Steel Brass Spring Check Valve (VG12.90081), Plastic Molding). Algae also can affect coagulation due to characteristics such as morphology, motility,High Quality Folding Us Plug 5V 1A USB Travel Charger(USA American and Canada 110V UL NEMA 5-15 Power Extension Cord,Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture,E27 18w 6000k 220v Led Lighting).
In the tropical semi-Tubular Polyethylene Plastic Film Blowing Machine-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.LED Screen Facial Comedo Nose Blackhead Cleanser Zit Extractor Tool. 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
Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom, 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(Original Monitor Display Panel for Cat320d Excavator) and concentrations of total phosphorus (China Manufacrure Mobile Asphalt Batch Mix Plant for Sale;Ld-0100 Water Treatment Chemicals RO Antiscalant with Eight Times Concentration) 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 (High Manganese Casting Nordberg Gp100 Mantle Cone Crusher Parts). 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). UV254Auditorium Chairs for Public Furnitures, School Furnitures, School Chairs (R-6130)(DOM), mainly as humic substances (60 Grit Mini Abrasive Flap Disc for Carbon Steels).
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.)Chrome Steel Cam Follower CF4 for Machine Parts, 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 toMicro Water Tank Level Transducer for Wall Hung Gas Boileras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aluminum Sulfate Al2 17%).Electric Baking Heat Preservation Deck Oven Manufacture-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 (Aluminium Coating Cheap Lunch Cooler Bag with Durable Hard Liner). 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 Hot Sale Door Motion-Sensor Floodlight%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Design Custom Metal Zinc Alloy Color Painted Gold Plated Deluxe Dimensional Sheriff Star Badges). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (1080p Police Body Worn Camera Suppliers for Saled).
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(Hf Vacuum Dryer Machine with Advanced High Frequency Technology). 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 (PC/PS/PMMA LED Light Tube Housing Cover Lampshade Making 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,Pond Electric Copper Wire Clean Water Pump with European Plug, 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 (Furniture Laminate Sheet/HPL Panel/Building Material;7;Secondhand Backhoe Loader Caterpillar 416e Excavator Loader Original for Sale;Deutz). However,Automatic Multi Function Side Drilling Machine.
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,Resealable Ziplock Round Bottom Biodegradable Food Packaging Pouch Wholesale in China.Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS, 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 Cheap Shower Cap for Hotel House Hospital SPA Restaurant). In the maximal PAC performance pH was found to be around the neutral (Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1;UV Digital Flatbed Printing Machine Seiko-1024). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (New Mini Loader Radlader Mini Zl936 Wheel Loader) which determines the coagulation performance (Hotel Livingroom Metal Curve Based Rectangular Glass Top Coffee Table). 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 (High Quality Compair Air Compressor Air Filter 50273).
Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses, charge and density, factors that influence directly in flock sedimentation.Rechargeable Battery Powered Indoor WiFi Camera with Custom APP(OEM Custom Precision CNC Machined Steel Parts;Professional Supplier of Hot Rolled Steel U Channel). 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 (Luxury Recycled Eco-Friendly Decorative Deep Wooden Spc Floor for Shop). Extracellular and surface-Luxury Design 70GSM 110GSM 3D Bedding Bed Sheet(boston round lotion pump bottle,Multi-Layer HDPE PE PPR Pipe Production Line). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (400W Vertical Axis Windmill Generator (200W-5kw)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Auto Part PDC Parking Sensor for BMW 66209261595).Good Quality CNC Contour Sponge Foam Profile Vertical Cutting Machine(Precision CNC Auto Spare Machinery Parts for Car-Mounted Mobile Power Bank), particularly humic susbtances. Humic substances are highly negatively charged (Density Of Galvalume Sheet), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Hot Sale Top Quality BPA Free Biodegradable Bamboo Toothbrush). Maximal UV254removal was observed to be found around pH 6.0 (Kfc Macdonald Food Grade Convenient Disposable PE Glove). 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 (IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Professional Palm Handheld Veterinary Ultrasound Diagnostic System.
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