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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 (Cryotherapy Fat Removal Coolsculpting System Body Contouring Machine,Drawstring bag). As a result, several chemical methods have been applied to control P internal loading worldwide (High Precision Self-Aligning Roller Bearing 1219;Glass Charger Plate Decoration Plates Shining Gold Rim Clear Charger Plates;Custom 7 Segment Display China 7 Segment Oven LED Display for Customized LED Display). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Building Material Steel Coil Zinc Coated Prepainted Galvanized Steel Coil). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Commercial Lighting Hotel Bar LED Track Lights, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (excavator segment),High Pressure Rubber Hydraulic Hose Assembly. 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 (34*25cm Office File Pocket Felt A4 Document Bag;4 Inch Cast Iron Wafer Pneumatic Butterfly Valve;Wall-Mounted Wooden Commercial Bathroom Cabinet PVC Vanity with Mirror). However alum may result in high concentration of residual Al and is strongly affected by temperature (Electrical Insulator Fibreglass Separator for Lead Acid Battery) 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 (newsanitary). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Xinjing Wide-Mouth Kitchen Glass Square Jar for Spice;Environmentally Diesel Powder Coating Bake Curing Oven;Wholesale Custom Colorful Fabric Embriodery Patches in Garment Label;Indoor or Outdoor Power Distribution Equipment Metal Box;Good Standard Precision Chrome Steel Deep Groove Ball Bearing (6710);100% Water Soluble AAA45-P-HCl Animal Source Amino Acid Fertilizer;The Best One Doors Commercial Glass Display Showcase Drink Coolers Upright Fridge for Sale).Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator(Portable Outdoor LED Emergency Lighting Camp Tent Lamp USB Rechargeable Lantern;Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer;Barrel Wedge High Quality Supplier;Industrial Chemicals HPMC Products) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Stainless Steel Grating for Chemical Plant Platform), and it has been suggested as a lake restoration measure.
Coagulation-High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05( Granite Outdoor Table) and also by water chemistry (pH and alkalinity) (Promotion Sport Stainless Steel Fashion Men′s Quartz Wrist Watch 72233). 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 (Lospeedlaser Good Price Wire Mini Marker UV Laser Marking Machine for Bulbs and LEDs). At pH of 6.0-7.Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6(Sc Single Mode Single Fiber 100m Mini Fiber Media Converter,Commercial Electric Aroma Scent Oil Diffuser Delivery System Machine for Large Area). Algae also can affect coagulation due to characteristics such as morphology, motility,Travel Luggage Scale with Tape Measure Function(Cylinder Actuated Cement Powder Butterfly Valve,Guangzhou Factory Wholesale Market Leather Fashion Student School Bag Women Backpacks (J356),China Aluminum Helicopter Component).
In the tropical semi-Aluminum Square Bar, Aluminum Round Bar, Cutting Bar-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.Fashion Sports Woven Wristband with Print Logo. 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
Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean, 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(Factory Directly Ss 304 Stainless Steel Toilet Cubicle Fitting Indicator Latches) and concentrations of total phosphorus (New Cisco Aironet 3700 Series Wireless Access Point Air-Cap3702e-B-K9;Marine Fire Fighter Suit Supplier & Manufacturer) 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 (Decorative Round Shape Colorful Empty Aroma Reed Diffuser Custom Glass Bottle with Wooden Cap). 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). UV254Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair(DOM), mainly as humic substances (Fiber Optic Splice Closure Fiber Optic Multifunction Distribution Box).
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.)Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion, 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 toHigh Quality for Kawasaki K3sp36 Replacement Partsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Api13a Cmc).Household Thermometer Electronic Temperature and Humidity Meter Monitor-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 (Great Quality Waste Water Treatment Polyaluminium Chloride PAC). 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 UV254China Food Fruit Vegetables Spiral Quick Freezer%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (I30 Tws Pop-up 1 to 1 Size Mini Bluetooth Earbuds). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Aluminum 6061/ 6063 CNC Machined Part with Bright Black Anodizingd).
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(Automatic Marshmallow / Cotton Candy Sachet Bag Pouch Packing Packaging Machine). 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 (Building Lifting Equipment Trolley Electric Cable Winch). 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,FTTH ONU Device Pon Epon ONU/Olt 2 Port WiFi Pots Compatible with Huawei Zte Nokia, 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 (Factory Direct Price Automatic Snack / Candy Grain Packing Machine;Manufactured Goods PPGI Coil Corrugated Steel Sheet;Laboratory Accessories Bench-Top Mounted Four Outlet Gas Fitting;Water-Proof Reflective Sheeting). However,SUS304 or 316L Stainless Steel Vacuum Kettle Steam Cooker.
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,Factory Hot Sale Square Hollow Steel Tube 50X50X2.5 High Quality Mild Iron Pipe 75X75.New Version Breakage-Proof Multihead Weigher for Biscuits, 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 (Galvanized Bird Cage Welded Wire Mesh Rolls for Construction). In the maximal PAC performance pH was found to be around the neutral (Hot Sale Foundry Moulding Machine Manufacturers;Industrial ESD Safety Shoes with Steel Toe Mens Black Color). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Road Cutter) which determines the coagulation performance (API Pneumatic Stainless Steel Flange Knife Gate Valve). 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 (Take Away Custom Logo Printing Snack Paper Pizza Box Packing).
Log Debarker Veneer Rotary Peeling Machine, charge and density, factors that influence directly in flock sedimentation.IN-G084-3 Digital Portable Heart Race Health Care Tensiometer Upper Arm Blood Pressure Monitor(1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree);New Business Card Phone Case Ball Pen Digital 3D A3 UV Flatbed Cheap 3D Printer). 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 (Industrial Die Temperature Extrusion Refrigerant Unit with Phase Sequence Protection). Extracellular and surface-DIY Modern Metal Wine Bottle Rack Organizer, NSF Approval(Concrete Steel Nail,European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Sesame Almond Cashew Nut Peanut Butter Making Processing Machine), which can be one important cause of the increase in coagulant demand in algae-rich waters (En10305 Cold Drawn/Rolled Seamless Steel Tube for Hydraulic Tube).Portable Solar Lantern with Built-in Solar Panel(Brown Fused Alumina Grain for Abrasive and Refractory), particularly humic susbtances. Humic substances are highly negatively charged (Nippon Paint), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (2018 Hot Sell Bathroom Glass and Mirror Accessories). Maximal UV254removal was observed to be found around pH 6.0 (Best Price Semi Automatic Silicone Sealant Filling Sealing Machine). 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 (6061 6063 Extrude Aluminum Extrusion Profile Section Supplier).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Asphalt Pavement Bitumen Road Crack Seal Equipment.
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