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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 (Ventilation Back Draught Damper Volume Control Damper One Way Shutter Actuators,Rubber Hose Gasket). As a result, several chemical methods have been applied to control P internal loading worldwide (Hand Tools Mini Wire Brush Set for Construction 3PCS OEM;Food Grade Titanium Dioxide F-200 Pigment;Silicone Rubber Pin Insulator/Polymer Composite Insulator (10kv-33kv)). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Customized Waterproof Backpack Canvas Laptop Bag). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Mosquito Screen Clothing),Custom Sport Event Antique Brass Plated Lanyard Available Medal. 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 (Medical Acupoint Patch with Sterile Wound Patch for All People;Carbide 4 Flutes HRC60 Blue Coated Milling Cutters;Lockey Loto Durable Standard Safety Gate Valve Lockout with Ce). However alum may result in high concentration of residual Al and is strongly affected by temperature (10~2500kVA (10KV) Cast Resin Dry Type Transformer with IP20 Enclosure) 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 (VDE Standard Colored Rubber Braided Thread 2X0.5 Electric Cable Wire). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (NIBP Cuff Blood Pressure Cuff Disposable of Patient Monitor;CNC Flame Plasma Cutting Machine Flame Cutting Nozzle;Air-Cooled Refrigeration Condenser Dual Flow Unit Cooler Air-Cooled Condensing Unit;14 X 14 Mesh Window Screen Aluminum Alloy Wire Netting;1100/1200/1060/1070 Polished Aluminium Strip for Indoor Decoration;Food Safety Testing Equipment for Heavy Metal in Food Analysis;Hc-30A Electrical Insulation Tape Winding Machine for Wire and Cable).Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker(factory outlet excellent herbicide DIURON 80% WDG on sale;Large Outdoor Water Park Slide/Water Turntable Amusement Equipment;BLDC 0625 Long Lifetime Mini Brushless Smallest DC Vibration Motor;Pond Electric Copper Wire Clean Water Pump with European Plug) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Customized Disposable BBQ Bamboo Round Stick and Skewers.), and it has been suggested as a lake restoration measure.
Coagulation-4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale(Wholesale Custom Microfibre Towel Rack Cooling Gym Yoga Bath Towel) and also by water chemistry (pH and alkalinity) (High Quality Honeycomb Ceramic Proppant / Filter Catalyst Supported for Mechanical Equipment). 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 (Battery Operated 8 Light Mode Christmas Gingerbread Man Pendant LED String Light). At pH of 6.0-7.Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra(Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line,CNC Fiber Laser Marking/Engraving Engraver for Metal and Nonmetal). Algae also can affect coagulation due to characteristics such as morphology, motility,Factory Manufacture Clear and Brown BOPP Packaging Tape(18 Inches Double Shafts Driving Xk-450 Rubber Rolling Mill,High Drying Efficiency Wood Sawdust Dryer for Sale,Solar connector).
In the tropical semi-2019 New Product 12mm Mini Short Metal Push Button Switch-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.Ae Bifacial Solar PV Panel 270W Poly German Quality. 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 Virgin PMMA 3mm Clear Cast Acrylic Sheet Price, 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(Ex-Proof Motorized Flange End Ball Valve (PQ9B41F-300Lb)) and concentrations of total phosphorus (Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date;Laboratory Rubber Compound Two Roll Mill Open Mixing Mill Machine) 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 (Permanent Magnetic Grid for Europe Market). 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). UV254LED Display Fixed Co Gas Monitor Toxic Gases Analyzing(DOM), mainly as humic substances (Vibratory Finishing Polishing Machine for Aluminum Brass Metal Steel Parts).
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.)New Product Ideas Wooden Musical Jewelry Storage Box, 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 to10m 3.5mm Male to Female Audio Cable for iPhone iPodas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(SAMSUNG).PPGI/PPGL Corrugated Steel Roofing Sheet for New Building Construction Material-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 (Reusable 90 Degree Elbow Spherical Seal Hydraulic Female Hose Fitting 20191). 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 UV254Surgical Instrument LED Shadowless Operation Lamp%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Multipurpose Rutile Titanium Dioxide TiO2 Pigment). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cheap Wholesale OEM High Precision Aluminum Die Casting Auto Partsd).
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(Fast Inflatable Air Bag Sofa Lounge Lazy Chair Bag Camping Bed Beach Hangout). 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 (Dr3008 Male&Female NPT Swivel Type Metal Brass Ferrule Valves). 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,Galvanized Razor Barbed Wire with Ce and SGS for Livestock Farm, 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 (Wholesale Fashion Designer Customs Sunglasses Square Men Sunglasses;Disposable Non-Vented Spin Connector IV Giving Infusion Set with Needle Luer Slip Lock Air Vent;Wire to Board Spring Type Connector Sy141-2.54mm Made in China;13L Popular Retro Metal Beer Ice Cooler for Camping Picnic Party). However,OEM Waterproof Travel Mummy Baby Changing Feeder Diaper Bag.
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,380V/220V VFD Variable Frequency Drive 50Hz/60Hz for Fun.Multi-Function Solar Power Generation System for Remote Areas, 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 (High Speed PVC Extrusion for Insulation Electrical Wire House Wire). In the maximal PAC performance pH was found to be around the neutral (Fancy Personalized Charm Simple Crown Trendy 925 Sterling Silver White Gold Bracelet;5X5m Aluminum High Peak Gazebo Pagoda Tent for Events). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (PVC Coated Galvanized 12 Guage Iron Baling Wire) which determines the coagulation performance (1616 Aluminum LED Strip Channel Surface Mount LED Extrusion). 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 (PVC Coated /Zinc Coated /Plastic Spray Chain Link Fence).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Lead Acid Battery Electric Sightseeing Car with 4 Seater (DN-4).
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