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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 (Color Shifting Chameleon Pigment for Car Paint Factory,Cheap White Pastry Packaging Box with Window). As a result, several chemical methods have been applied to control P internal loading worldwide (Basic Series Solar Powered Fixed Shade Auto Darkening Welding Helmet;Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe;18.5 Pct Capacitive Touch Screen Monitor Open Frame Design Interactive Display). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (18mm Red/Black/Dynea Film Faced Marine Plywood Construction Building Material). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Ceramic Tile Plasma Ion Deposition Planting Functional PVD Vacuum Coating Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Fiebr Laser Cutting Machine Without Cover),Multi Span Venlo Type Agriculture Production Glass Greenhouse. 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 (LSR Injection Mold Tooling for Medical Nipple;High Quality Cheap Hygienic Grade Sap Sodium Polyacrylate for Cooling Packing;Nonwoven Polyester Fiber Pillow Making Plant (ZXJ-787)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw) 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 (Smart Charger For Mobile Phone). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Super Cool Hotel 100GSM Drawstring Black Non-Woven Laundry Bag;Private Label Washing Laundry Powder Detergent;New Product 2019 Milky White Electrochromic Smart Film; Transparent Acrylic Double-Sided Tape;Chinese Antique Panel Business Hotel Wardrobe Furniture Hospitality Industry;Fashion Design Steel-Wood Large Conference Table;Balaclava Hood Ski Bike Cycling Face Mask Cap Fleeces Helmet).Video Tripods Monopod Self Aluminum Camera Tripod(Easy to Use Mobile Filter Unit for Light to Medium Welding;8FT Face Veneer Rotary Peeling Lathe for Wood Log Cutting Line;School Notebook Printing Exercise Book for Students Customised Stationery;Dry Ice Production Block Cube Maker Producer Refrigeration Industry Use Machine) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Best Seller Canvas Striped Cotton Rope Fabric Hanging Hammock), and it has been suggested as a lake restoration measure.
Coagulation-Belt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)(Topkit Tower Crane Rct6011-6 for Construction Building) and also by water chemistry (pH and alkalinity) (Motion Sensor Light Stick Closet Light Wall LED Night Light). 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 (Jacketed Electric Heating Reactor). At pH of 6.0-7.0.5-1.5mm Broken Silica Gel with 35% Moisture Absorption in 25kg Bulk Bag(China Stainless Steel Clamp Sanitary Ball Check Butterfly Valve,2-7dBi GPS/GSM SMA RF Coaxial High Gain WiFi Antenna). Algae also can affect coagulation due to characteristics such as morphology, motility,Modern Ladies Clothes Shop Design for Clothing Store Display(P810 Indoor & Outdoor Single Color Vehicle LED Display Module,Wholesale Winter Snow Boots Dog Shoes Pet Slip-Resistant Shoes for Dog,Gabion Mesh Machine).
In the tropical semi-Flexible Cloth Backdrop P18 3X6m LED Video Curtain-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.BAA9A79 Single Wall Borosilicate Square Drinking Glass Cup with Handle. 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
Fsi 5kw 24VDC Pure Sine Wave Hybrid PV Solar Inverter with High Efficiency MPPT Controller, 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(Plastic PVC/WPC Granulator Die Face Cutter Extruder Machine) and concentrations of total phosphorus (Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose;Flame/Tear/Heat/Wear/Cold Resistance Wire Mesh Steel Cord Conveyor Belt) 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 (Nki Radial Needle Roller Bearing Nki 35/30 Needle Bearing with Inner Ring). 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). UV254Telescopic Chenille Microfiber Double Sides Flat Mop for Easy Cleaning (1014)(DOM), mainly as humic substances (CNC Machining Milling Aluminum Bike Components).
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.)Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy, 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 toEV850m CNC Machine High Precision Vertical Machining Centers Priceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Iqf Tunnel Freezer For Fish).Clear Flat Cellophane Bakery, Cookies, Candies, Dessert Treat Roll Bags-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 (Popular Classic Design Old Style Vintage Leather Chesterfield Sectional Sofa). 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 UV25410W-1000W Servo Motor, Energy Saving Industrial Sewing Machine Servo Motor%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Yg15/Yg8 Mirror Polished Hip Sintered Tungsten Carbide Wire Guide Rollers). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (m.displayshowcase.comd).
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(Excellent Quality Wooden Cosmetic Display Counter for Retail Store). 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 (Cheap Customized PVC Rubber Book Mark Clips with Any Logo Design for Promotion/Advertising (XF-BM10-)). 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,New Design Neoprene Beer Can Cooler, Hero Drink Stubby Cooler, 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 (Industrial and Commercial Screw Compressor Water Chiller;Qbeka Anti-Aging Serum Qbeka Copper Peptide Tendering Serum Anti Wrinkle Serum Face Serum;Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097);New Condition Hot Sale Type Air Cooled Ice Cube Maker). However,99% Nano Grade Electronic Use Titanium Dioxide.
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,630kgs Galvanized Suspended Platform, Electrical Suspend Working Platform, Swing Stage.A76 Nordic Living Room Dining Room Furniture, 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 (1325 High Quality Steel Aluminum Metal Plasma Cutting Machine). In the maximal PAC performance pH was found to be around the neutral (Latest Design House Sandal Disposable Hotel Slipper;Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Thin Wall 7049 7050 Aluminum Tube with PVC Package) which determines the coagulation performance (Century Mosaic Tile Factory OEM/ODM Products). 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 (1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Tensile Strength Stainless Steel Wire From Factory.
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