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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 (Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid,Laser Cutting Machine Made In Germany). As a result, several chemical methods have been applied to control P internal loading worldwide (Custom Dye Sublimation Printed Phone Lanyard ID Badge Holder with Logo Custom;Cotton/Polyester/Spandex Interlock for Clothing;Industrial Gear Driven Concrete Marble Terrazzo Floor Grinding Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hip-Hop Streetwear Custom Brand Fashion Man Hoodie, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Slippers Plush),Boiler Seamless Steel Tube En10216-216mo3, Steel Pressure Tube Pipe 25crmo4. 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 (Cheap CNC Leather Oscillating Knife Cutting Machine Milling Head Knife Head Cutter;Bh36/Dh36/Ah36 Hot Rolled Marine Steel Shipbuilding Plate;Z21 Type High Precision Flexible Locking Coupling Assembly Device). However alum may result in high concentration of residual Al and is strongly affected by temperature (Certified 100% Natural & Pure Organic Basil Herbs Oil) 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 (Straw Crushing). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Class125 Double Disc Wafer Swing Check Valve;Wholesale Ground Vulcan Earth Screw Anchor for Rail and Highways;Juki Pick and Place 40071585 Head Vacuum Unit Asm for Ke3020 SMT Machine Original New in Stock;Polyethylene Strap Polypropylene Band Pet Packing Tape Pet Strapping Band Making Machine;Velvet Armchair;Europe Good Quality and Cheap Price High Efficiency Swimming Pool Water Heater Heat Pump;Crystal or Plastic Pendant Lamp).Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine(Long Using Time Rechargeable Cordless Hair Clipper;Metallized Film for Laminating Color Printing Packaging Materials;Fiber Laser Cutting Machine for Metal Tube and Sheet Cut;Garde 4.8/8.8 DIN 603 Carriage Bolt/Mushroom Round Head Bolt) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (2017 Hot Selling Wooden Blinds with Cover Valance), and it has been suggested as a lake restoration measure.
Coagulation-Rgt-16-Ye Ruler Baby Scale 16kg, Mechanical Infant Scale(Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom) and also by water chemistry (pH and alkalinity) (White Coated C2s Art Paper for Printing Magazine (610MM ROLL WIDTH)). 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 (Custom Shaft Machining). At pH of 6.0-7.Cheap 85 Inch Touch Screen Infrared Interactive Whiteboard Smart TV for Classroom(Galvanized Steel Plate Assembled for Corn Storage Silo,4 Stage Ture HEPA Filter Ionic Air Purifier with 4 Fan Speed). Algae also can affect coagulation due to characteristics such as morphology, motility,Wholesale Men′s Leather Waterproof Outdoor Trekking Boots(Molten Steel Ladle for Casting,CCTV 8.0MP 4K Video Security Surveillance IR Dome Ahd Camera,Punching (HS-SM-07)).
In the tropical semi-10kw 20kw 30kw 50kw Small Gas Generator for Home Use-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.Eco-Friendly FDA OEM Biodegradable Natural Bamboo Tongue Scraper Toothbrush. 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
P3 Six Faces Indoor Full Color Irregular Shape Magic Cube LED Display Screen, 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(RO Water Plant System Water Sediment Filter Machine) and concentrations of total phosphorus (15m 17m 3 Arms R Shape Trailer Mobile Spider Concrete Placing Boom on Sale;Digital Printed Tea Towel) 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 (China Suppliers Factory Paper Machine Industrial Ss Cylinder Mould). 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). UV254Eye Bolt Screw Stainless Steel Fastener for Aluminium Profiles(DOM), mainly as humic substances (High Precision Mini Micro Button Load Cell).
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.)Used Komatsu PC60-7 Crawler Excavator Komatsu 6ton Mini Digger for Sale, 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 tofor Communication Telecom Rg Series 50 Ohm Coaxial Cable Rg58 Cableas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Aluminum Roof Skylight Bright Awning Window).Handles Operated Cast Iron EPDM Seat Wafer Butterfly Valve-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 (Stranded Loose Tube Armoured Direct Buried Underground Optical Fiber Cable). 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 UV254DC Colorful Battery Operated Small Hand Fan for Outdoor Use%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Prepainted Galvanized PPGI Corrugated Steel Roof Plate Roofing Sheet Best Price). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Performance Cooling Stainless Steel Tube Copper Fin Evaporatord).
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(12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires). 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 ( Digital Thermometer E278). 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,Heavy Duty Cast Ductile Iron Manhole Cover with Concrete Infill, Solid Top, for Sewer, Stormwater, 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 (Good Price Optical Cylindrical Lens for Laser Light;Different Kinds Butterfly Hot Melt Adhesive Applique Embroidery Patches;Single Quartz Tube Medium Infrared Carbon Fiber Heater;Marble Sculpture Statue Carved Stone Carving for Garden Decoration (SY-X1569)). However,Plastic Round Home Storage Box Vacuum Insulated Lunch Box.
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,Jarliet 140cm Big Breast Mini Sex Love Doll for Men Sex Masturbation.HDPE Vented Nestable and Stackable Plastic Fruit Vegetable Crate for Storage, 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 (UV LED Varnish Digital Flatbed Printing Printer Machine for Wood Glass Metal A1). In the maximal PAC performance pH was found to be around the neutral (Customized Promotional 100% Cotton 6 Panels Baseball Cap with Printing Logo;Vertical Waste Plastics/Cloth/Cardboard Hydraulic Press Waste Paper Baler Baling Machine). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Factory Price Capstan Hydraulic Winch 5 Ton) which determines the coagulation performance (Copper Nickel Resistance Wire). 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 (Washroom Water Tap of Hot and Cold Water Mixer).
Five Brushes Car Wash Rollover Car Washing Wholesale, charge and density, factors that influence directly in flock sedimentation.Customized High Performance Industrial Oil Hydraulic Cylinder for Metallurgical Industry(Low Insertion Loss St Upc Singlemode Simplex Fiber Optic Adapter;China Most Professional Factory 316L Stainless Steel Round Seamless Decorative Pipe Tube). 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 (Living Room Furniture TV Stand Electric Fireplace with No Heating). Extracellular and surface-Large 25X100m Exhibition 2500 Seat Tent for Trade Show(Powder Coating Machine,High Quality 11oz Bone China Color Change Mugs Sublimation Coating Mugs (Matte)). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Smart Electronic RoHS Weighing Scale PCB Manufacturer with Fast Delivery), which can be one important cause of the increase in coagulant demand in algae-rich waters (Zinc-Plated Carbon Steel Tiger Clamp Spiral Double Bolts Clamp).Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110)(Best Electric Roll on Paraffin Wax Heater for Sale), particularly humic susbtances. Humic substances are highly negatively charged (Dome Tent Geodesic), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Industrial Series Mbar Low Pressure Gauge with Phenolic Case). Maximal UV254removal was observed to be found around pH 6.0 ( Pipe Flanges Schedule 40). 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 (Speed Sensor 8-97328058-1 Odometer Sensor for Isuzu).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Spiral Flat Metal Pot Scourer for Kitchen Cleaning Ball.
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