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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 (Steel Warehouse Metallic Curved Roof Design Structure,Electronic Circuit). As a result, several chemical methods have been applied to control P internal loading worldwide ( Drum Sand Rotary Dryer;for Lose Weight Tesamorelin Pharmaceutical Intermediate;China Factory Entry Security Type Steel Door with Low Price). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hot Sale Hotel Use Imitated Marble Toothbrush Holder (BP2612-YS)). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,HS Code: 2836200000 Sodium Bicarbonate Factory Price, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cotton Gloves For Dry Hands),High Tensile Strength Stainless Steel Wire From Factory. 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 (Hot Selling Round Cookware Pan with Induction Bottom Frying Pan;Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls;Latest Popular off Road Electric Citycoco 1500W 2018 Scooter). However alum may result in high concentration of residual Al and is strongly affected by temperature (China Factory Wholesales Common Wire Nails Common Nails High Quality Low Price Polished Iron Nail) 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 (Best Wireless Charger Manufacturers Cheap Price). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Blince Omsy Series Danfoss Oms Orbital Hyydraulic Motor for Drilling Rig Machine;Self-Propelled Ride on Concrete Floor Grinder Grinding Machine Gyg-780;Household Digital Kinetic Luggage Weighing Scale with Belt-Uniquely Designed (SLU046);Medical High Precision Aluminum Alloy Parts Machining for Medical Service;www.abotled.com;Single-Acting Hydraulic Cylinder for Dump Truck;Best Price Slewing Ring Bearings for Crane Wind Turbine System).ISO14001 & Ce Commercial Gym Adjustable Decline Bench 5037(150ml Plastic Cosmetic Cream Jar with Label Made in Yuyao;Customized Different Red Copper/Brass Hex/Coupling/Teeth/Slotted/Square Nuts;Ip55 Asynchronous Induction Electric Motor;Food Grade Stainless Steel Custom Brewing Equipment Tank Brewery) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Alcohol Swabs Wipes Pads Tissue Packaging Machine Price), and it has been suggested as a lake restoration measure.
Coagulation-Decorative Metal Aluminum Steel Room Divider Modular Partition for Hotel Restaurant(Modular LED Lamps LED Flood Light 50W-500W Replace Indicator Lamps Hidden 2000W) and also by water chemistry (pH and alkalinity) (Good Cleaner Cotton Rope Mop Wood Mop Stick). 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 (Superfine Yttrium Stabilized Zirconia). At pH of 6.0-7.England Conference Room Design Toronto Canada Conference Table with Metal Base in Specification(Customized Cast Iron Ak41 Type V-Belt Pulley for 4L,Red Enamel Cast Iron Fondue Pot with Forks). Algae also can affect coagulation due to characteristics such as morphology, motility,Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice(Automatic White Cardboard Paper Roll to Sheet Cutting Machine,Rust Resistance Anti Climb Protective Aluminum Durable Outdoor Metal Fence for Garden/Factory,Black Nut).
In the tropical semi-Different Gauge Hot Dippep Galvanized Purlin Metal Steel Sheet Coil for Roofing Sheet Price-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.60W BLDC Ceiling Fan Light Driver, DC Brushless Fan Light PCBA. 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
Three Layers ABC Co-Extrusion PP Film Blowing Machine, 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(Industry Basket Washing Machine Crate Washer) and concentrations of total phosphorus (Colorful Mobile Phone Accessory Dull Polish Back Cover PC Phone Case for Meizu Note 6;35kVA 100kVA Silent Canopy Cummins Diesel Generator) 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 (PP Yarn Water Filter Cartridge for Large Flow Rate). 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). UV254Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc(DOM), mainly as humic substances (2019 New Products Wall-Mounted Household Natural Gas Alarm Low Power).
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.)4*0.22mm2 Core Unshielded Fire Alarm Cable 18awg, 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 to 42′ LG LED TV Backlight Lens Strips/Bars/Spearsas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(18 Gauge Aluminum Sheet Metal).Jelly Patent Mirror Face Napa Artificial PU/PVC Leather for Shoes Materials-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 (Solar PV Detached 30W 12inch Roof Mount Solar Ventilation Attic Vent (SN2014003)). 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 UV254Solar Power Refrigerator 12V DC Mini Fridge%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Chinese 1kw Vertical Axis Wind Turbine for Home Use). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PA PP PE Flexible Plastic Corrugated Wire Loom Tubingd).
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( Temperature Controller Thermostat 110V for Cabinet Use). 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 (11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer). 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,1 2 3 4 5 6 8 10 12 14 16 18 20 24 26 Inch Pneumatic Flanged Valve with Actuator, 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 (200m Deep Top Driving Tractor Mounted Water Well Drill Equipment;20FT T11 T14 Transport Tank Container Motor Oil ISO Tank Container;Customized EPS/EPP Mold From Factory with ISO;Eco-Friendly Heating Wok). However,Fastener Carbon Steel Galvanized Zinc Plated Hex Bolt DIN931 933 ANSI B18.2.1.
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,Electro Galvanized Iron Wire, /SGS Galvanized Iron Wire/Bwg 22 8kg Electro Galvanized IR.Ad-P720 Hot-Selling Perfume Glass Bottle 100ml, 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 ( Label). In the maximal PAC performance pH was found to be around the neutral (304/304L 316/316L Seamless Stainless Steel Pipe for Heat Exchanger;Wooden Grain Siding Plank for Villa Integrated House). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Touch Screen Handheld PDA Barcode Scanner with 4G Bluetooth WiFi Camera GPS) which determines the coagulation performance (Metal Scrap Smelting Furnace Filtration System Gas Dust Air Filter Bags). 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 (Light Guide Plate Suppliers LED Acrylic Panel).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Pure Hyaluronic Acid Powder with Reasonable Price.
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