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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 (2017 New Material Fashion Luggage Good Suitcase,Electric Hydraulic Three-Station Bus Bar Cutting Punching Bending Machine for Copper Processing). As a result, several chemical methods have been applied to control P internal loading worldwide (600W Lower Costs CO2 Laser Tube for Flat Die Board Laser Cutting Machine;Plastic Injection Molding Machine for Nylon Cable Tie Mould Making;Indoor Commercial Economical Outdoor Public Heavy Duty Passenger Elevator Escalator (XNFT-001)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Good Quality Inner Climbing Tower Crane Qtz50 (5008)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Honkon Beauty SPA Skin Tighter and Acne Removal Mesogun Injector Beauty Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (High Compressive Strength High Alumina Refractory Bricks),Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula. 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 (Two Pieces Ss Manual Ball Valve with Female Threaded Connection;Stainless Steel Patient Record File Folder Medical Chart Holder;Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP)). However alum may result in high concentration of residual Al and is strongly affected by temperature (Bright Polished Galvanzied Common Iron Wire Nails) 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 (Glass Chamfering Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Wallbox Socket Type 2 32A 22kw Three Phase EV Charger for Smart Charge;Environmental Protection Material PLA Sheet for Cup Lid Tray Forming;Amusement Park Best Electronic Washing Ball Clean Dry Machine Cleaning Ball Machine;Bestsub Sublimation Square Ceramic Coaster W/ Cork (CBZ24);Pe Drain Tubing Supplier;8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe;Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors).BS5163 Metal seat non-rising stem cast iron gate valve PN16(Double Head Half/Full Threaded/Eye Wooden/Truss/Hex/Pan Self-Drilling/Tapping Screw;Good Price Automatic Liquid Sachet Juice Milk Drinking Water Pouch Filling Packing Packaging Machine;Strip Sweeper Brush;Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Good Performance High Precision Thrust Roller Bearing (29292)), and it has been suggested as a lake restoration measure.
Coagulation-Lower Price Luxury Waterproof Spc Vinyl Floor Tile(30% Al2O3 Content Yellow PAC for Wastewater Treatment) and also by water chemistry (pH and alkalinity) (ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling). 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 (Colorful VIP Festival Event Handband Fabric Woven Bracelet Wristband). At pH of 6.0-7.172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)(50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale,Precise Profile Wire Universal Rolling Mill). Algae also can affect coagulation due to characteristics such as morphology, motility,Galvanized Stainless Steel Square Wire Mesh with Ce and SGS(Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant,Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift,High Filter Machine/ Membrane Filter Press for Sale/China Filter Machine Manufacturer).
In the tropical semi-High Quality Viscose Rayon Embroidery Thread-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.Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer. 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
Fat Tire City Coco Electric Bicycle Motorcycl Bike Electric Scooter for Adult, 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(Classic Cafe Dining Chair with High Quality/Grey/Arm Chair) and concentrations of total phosphorus (Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould;Mini Electric Bike) 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 (220-240V 110-130V LED Wall Lamp Die-Casting Aluminum LED Garden Light). 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). UV254Medical Equipment One Step Tp Device Syphilis Rapid Test Kit(DOM), mainly as humic substances (Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)).
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.)20PCS Porcelain Dinnerware with Popular New Design, 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 toFashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rackas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Vacuum Pouch).OEM / ODM Steel Material Controllable Piston Gas Lift Pressure Adjustable Gas Spring for Bus Seat-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 (Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect). 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 UV254KCD-108 Series for Home Appliance Colourful Rocker Switch%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hotel Dental Kit Toothbrush Shaving Kit Razor Amenities Sets). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (www.madcmotor.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(High-Grade Hemp Rope Hanging Grain General Twine Hanging Grain Spot). 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 (50-5000L Commercial Craft Beer Brewery Equipment). 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,OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer, 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 (Pink Strapless Dress Trumpet Sleeves Sweet Party Luxury Prom Dress;2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging;High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015;Fat Bike). However,European VDE Schuko 3-Pin Waterproof IP44 Power Plug.
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,Hot Most Industrial Outdoor Trampoline, Commercial Trampoline Park for Sale.12.5/80-18 16.9-24 16.9-28 Agriculture Backhoe Loader Tires, 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 (Home Furniture Metal Chair Grey Velvet Dining Chair). In the maximal PAC performance pH was found to be around the neutral (Swing Check Valve Stainless Steel Type Non Return Valve;Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250) which determines the coagulation performance (Stainless Steel Earring Supplier & Manufacturer). 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 (C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Stage LED Bar 54PCS*3W RGBW DJ Disco Stage Lights.
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