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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 (Hot Selling Commercial Moon Cake Machine / Automatic Encrusting Machine,Rattan Weaving Garden Sofa with Cushion Waterproof Tape Sofa Outdoor Furniture Indoor). As a result, several chemical methods have been applied to control P internal loading worldwide (Jonsen Flat Surface Grinder Precision Belt Sanding Polishing Machine;Industrial Fiber Laser Marking Machine for LED Lamp/Bearings/Rings;Cbb65 Air Conditioner Capacitor Polypropylene Film Capacitor). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Galvanized Stainless Steel Square Wire Mesh with Ce and SGS). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PP Grid Composite Safety Protection Netting for Construction Building, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Full Hd Wide Screen Fresh Design Led Tv),2018 Newest 12inch Music Sound Box for Computer. 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 (Professional Fishing Equipment Carbon Pole Rod for Sale;Ce Approved Panel 40W 48W LED Border Line Light with Mean Well Driver;Bonding Strength Testing Machine Servo Control Universal Tensile Strength Tester). However alum may result in high concentration of residual Al and is strongly affected by temperature (Boy Children EVA Beach Sandals Sport Sandals Flat Sandals (21jk1628)) 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 (6 Oz Paper Cups With Lids). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (2000W 60V Two Batteries City Coco Scooter Bike;ISO3821 Certified Grade R 1/4′′ 50FT Rubber Twin Welding Hose;Rebar Splicing of Reinforcement Bars Complying with Aci-318;Multi Span Venlo Type Agriculture Production Glass Greenhouse;Round Rectangular Rain Downspout Pipe High Speed Roll Forming Machine;SAA Approved 3 Phase Industrial Female Plug 66csc/66asc Industrial Switchgear IP66;Custom Logo Printing Silicone Waterproof Swim Swimming Cap for Promotion).800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights(Outdoor Full Color P6mm Front Maintenance LED Display;Water Treatment Chemicals RO Antiscalant Acidity for Groundwater;Raycus 50W Fiber Laser Marking Machine with Automatic Focusing System;Proessional PCB Assembly Fast PCB Manufacturer SMD PCBA Fr4 PCB Board Production) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Letter Size A4 Adhesive Sticker Shipping Self Adhesive Paper Labels), and it has been suggested as a lake restoration measure.
Coagulation-Kyn28-24 24kv Medium Voltage Metal-Clad Blokset Switchgear(China Factory Gk35 Sewing Machine for Bag with Conveyor) and also by water chemistry (pH and alkalinity) (Refrigerant R134A with Refillable Tped Approved Cylinder). 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 (Indoor Amusement Empty Arcade Cabinet Machine). At pH of 6.0-7.Miniature Bearing 1*3*1mm 681 Zz NSK NTN SKF Bearings (W681/1R)(Shr/IPL Laser for Hair Removal Skin Rejuvenation,Good Quality Custom Logo Wholesale Eco Friendly Natural Bamboo Toothbrush). Algae also can affect coagulation due to characteristics such as morphology, motility,Modern Design Stainless Steel Handrail Post Glass Balustrade Handrail(Full-Automatic Incense Sticks Counting and Packing Machine,Colorful Fashion Women Sneaker Walking Weave Shoes,9KW Face Mask Maker Machine).
In the tropical semi-Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell-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.Kid′s PVC Rainproof Rain Jacket with Full Print. 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
Outdoor High Pressure Isolating Vacuum Load Switch, 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 Temperature Resistance Tinned Copper Flexible Teflon Silicone Rubber Wire) and concentrations of total phosphorus (Colored Asbestos Free Fiber Cement Board Exterior Wall Sheet;Travel Jewelry Storage Bag) 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 (Electronic 4-20mA 0-5V 0-10V Pressure Sensor Switch with on/off PNP/NPN Switching). 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). UV254Precision Assembly Jigs Fixtures for Car Outlet(DOM), mainly as humic substances (China Tamping Rammer with Hondagx160 Supplier).
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.)China Cheaper Plasma 1325 1530 Metal Plasma Metal Cutting Machine, 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 toCheap Outdoor Patio Rattan Hotel Furnitureas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Customized Cotton Pullover Hoodies with Embroidery Logo Company Workwear Hoodie).Fish Scale Shaped Waterproof Roof Tile for Roof Tile-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 (Reflective Police Protective Uniform for Working Vest). 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 UV254Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Junction Plate Connect Board Bracket Stamping Made). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Wheel Nut Cross Wrenchd).
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(China PS Printing Plates Positive PS Plate Maker). 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 (Extra White Masterbatch 60% Anatase TiO2 for PE Films). 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,30% Al2O3 Content Yellow PAC for Wastewater Treatment, 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 (Armor Thermocouples / Thermal Resistance Temperature Sensor;Classical Gym and Commercial Fitness Equipmen Decline Bench T40;Junjian Precooling Air Pump Cheap Chinese Commercial Ice Cream Machine Bql-368;www.wwtpcn.com). However,Hydraulic Press Machine Deep Drawing Press 100 Ton.
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,Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date.High Carbon Steel Wire Lead Patenting Phosphate Production Line, 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 (China Aluminum Rigid Inflatable Boat 5.2m Aluminum Rib Boat with PVC or Hypalon Tube). In the maximal PAC performance pH was found to be around the neutral (Ductile Iron Sand Cast Iron Pipe Fittings Threaded Blank Flange;Travel Cutlery Set Fork Spoon Chopsticks Straws Brush Packed in Wheat Box and Pouch). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Steel Frame Fabricated Bird Poultry Broiler Farm Shed Building) which determines the coagulation performance (Factory Wholesale Customize Porcelain Coffee Mug with Decoration Firing Logo). 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 (One Time PS Foam Plate Food Container Making Machine (MT105/120)).
Furniture Laminate Sheet/HPL Panel/Building Material, charge and density, factors that influence directly in flock sedimentation.Woodworking Machine One Head Economic Model CNC Router(4we5 Electrically Operated Directional Control Valves;200/375/500ml Empty Crystal Vodka Glass Wine Bottles Straight Decanter). 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 (Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric). Extracellular and surface-Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event(Motorcycle Spare Part Motorcycle Engine Kit Gaskets for YAMAHA Fz16-Oumurs,Customized Precision Aluminum Die Casting Machining). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Interlocking Foam XPE Gym Mats in Martial Arts), which can be one important cause of the increase in coagulant demand in algae-rich waters (2019 Novelty Eco Friendly 16oz Plastic Cup Unbreakable Wine Glass).Customized EPDM NBR Rubber Bellows Expansion Joint(275ml Ice Beer Cocktail Carbonated Drink Glass Bottle), particularly humic susbtances. Humic substances are highly negatively charged (Restaurant Furniture Industrial Vintage Toledo Wooden Bar Stools Dining Chairs), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles ( Peanut Dxd-550s). Maximal UV254removal was observed to be found around pH 6.0 (100%Cotton Woven Jacquard Brand Design Beach Towel). 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 (Steel Warehouse Metallic Curved Roof Design Structure).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Speed 6 Color PP Woven Bag Printing Machine.
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