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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 (Two Pieces Ss Manual Ball Valve with Female Threaded Connection,m.displayshowcase.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Stainless Steel Patient Record File Folder Medical Chart Holder;Digital Electronic Body Fat Personal Bluetooth Health Weighing Scale (SBF097BT-WTP);Bright Polished Galvanzied Common Iron Wire Nails). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wallbox Socket Type 2 32A 22kw Three Phase EV Charger for Smart Charge). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fashion Double Striped Non-Slip Entrance Mat, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (China Pvc Slat Panel For Ceiling),145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe. 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 (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)). However alum may result in high concentration of residual Al and is strongly affected by temperature (8 Inch Carbon Mechanical Properties of St35 Schedule 40 Steel Pipe) 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 (New Condition Hot Sale Type Air Cooled Ice Cube Maker). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Portable Aluminum Airbag Used Air Compressor Tank for 12V Air Compressors;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;Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector;Century Mosaic Tile Factory OEM/ODM Products;Good Performance High Precision Thrust Roller Bearing (29292);30% Al2O3 Content Yellow PAC for Wastewater Treatment).Stainless Steel Perforated Metal Grain Sieve(ASTM Good Price Carbon Steel Carbon Stainless Steel Pipe in Hot Selling;50*50*25mm Strong Neodymium Block N35 Permanent NdFeB Magnet for Sale;Tropical Fruit Seeds;Precise Profile Wire Universal Rolling Mill) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Popular Blue Colour Changing Raw Material 1-3/2-4/3-5mm Silica Gel Desiccant), and it has been suggested as a lake restoration measure.
Coagulation-Stainless Steel Grating for Chemical Plant Platform(Semi Electric Pallet Stacker Price 2 Ton Pallet Forklift) and also by water chemistry (pH and alkalinity) (Sinicline Custom Printing Display Packaging Self-Sealing Plastic Bag). 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 (Diamond Multi-Wire for Granite Slab Cutting/Diamond Wire for Granite Squaring). At pH of 6.0-7.Pet Strap Production Line with Good Quality(Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer,Classic Cafe Dining Chair with High Quality/Grey/Arm Chair). Algae also can affect coagulation due to characteristics such as morphology, motility,Commercial Lighting Hotel Bar LED Track Lights(Factory Directly Custom Promotional Cheap Bulk Buy Silicone Wristband Mould,Cosmetic OEM Gold Pet Foam Bottle for Cosmetic Packaging and Face Cleam,Cordyceps Sinensis Extract Powder).
In the tropical semi-High Pressure Rubber Hydraulic Hose Assembly-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.Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator. 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
High Quality Adjustable Ball Valve Lockout for 13-70mm Pipe Bd-F05, 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(Pet Factory Wholesale Black Climbing Wooden Cat Tree (YS98797)) and concentrations of total phosphorus (High Quality Standard Cum B3.3 Water Temperature Sensor for Excavator;University BS 476-6 Flame Tester Flammability Analyzer for Building Materials) 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 (Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack). 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). UV254Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6(DOM), mainly as humic substances (Lightweight Camouflage Outdoor Combat Military Tactical Molle Vest).
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.)Travel Luggage Scale with Tape Measure Function, 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 toPermanent N50 Tiny Mini Neodymium Magnet for Saleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Plastic Small Garden Fence Plastic Safety Fence Net).Aluminum Square Bar, Aluminum Round Bar, Cutting Bar-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 (Men′s Polyester Moto-Boy Hunting Jacket Clothing). 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 UV254Fashion Sports Woven Wristband with Print Logo%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (2018 Chinese Single Person Best Plastic Fishing Kayak Sit on Top). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Construction Hoist Back Roller Exporter Hot Sale Productd).
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(2017 Luxury Acrylic Double Jar White Jar for Cosmetic Packaging). 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 (High Speed Promotional Plastic Custom USB Flash Drive U016/Sy015). 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,Facial Cleaning Cellulose Sponge for Cosmetics Makeup Brush Clean, 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 (Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve;Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250;C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm;Beauty Cavitation RF Body Slimming Machine V8). However,Aluminium Fabric Garden Coffee Shop Outdoor Dinning Chair.
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,Comfort Rubber Cow Stable Stall Rubber Matting/Mattress/Mat with Fabric Insertion.Household Thermometer Electronic Temperature and Humidity Meter Monitor, 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 (KCD-108 Series for Home Appliance Colourful Rocker Switch). In the maximal PAC performance pH was found to be around the neutral (High Quality Watermark Brass Square Bottle Trap in Gold;Stainless Steel Checkered Plate 304 316L 410 Floor Material). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Snowkey Meat Processing Cooling Flake Ice Making Machine) which determines the coagulation performance (LED Fog Car Headlight 30W LED Fog Light for Jeeps). 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 (Custom Aluminum Die Casting Parts for Medical Equipment).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Version Breakage-Proof Multihead Weigher for Biscuits.
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