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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 (2 Pin Waterproof Soldering Socket Waterproof Extension Cord Connectors,Pvc Gym Flooring). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Defrost Island Supermarket Freezer for Frozen Foods Display (RG-20);Kunlun Paraffin Waxes From Petroleum Made in China;Ce Certificate Factory Provide Drink Water Vending Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Down Film Rolling Bag Wrapping Big Bread Packing Machinery 450X). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Sheet Metal Stamping Galvanized Steel Panel and Frame, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Fish Cans Sealing Machine Tomato Paste Cans Sealing Machine),Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging. 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 (CNC Machine Linear Guide Accordion Bellows Cover;Metal Wire Mesh Knitting Scourer Machine with 220V 380V Voltage;Brown Shoes High Quality Strong Protection Working Shoes). However alum may result in high concentration of residual Al and is strongly affected by temperature (100% Pure PC Suitcase Luggage Aluminum Trolley Bags for Travel) 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 (Plastic PVC Single Color Coil Floor Mat). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (School Exercise Book Making Machine 2.3.4 Colors;Syrup Piston Filling/Cream Liquid Bottle Filling Machine;Bubble Cloth Seersucker Honeycomb Style Polyamide Knit Bikini Fabric;Plastic Tpd E Juice Bottle 10ml with Colorful Cap;Galvanized C Purlin;LG953 LG956 LG958 Front End Loader Parts Sleeve/Bushing 29270001031;Fast Thermal Cycling High Heat Temperatures Resistance 99% Alumina Ceramic Insulator Rod).Infrared Thermometer, Thermometer, Non-Contact Thermometer Gt750(Digital Spirit Level Protractor Angle Gauge Meter Bevel Digital Inclinometer;IEC Standard FC APC PLC Splitter for Gpon Equipment;Aluminium Alloy Photo Chemical Etching Acoustic Perforated Metal Mesh;Tablet Replacement Parts for Samsung Tab 3 Gt-P5200 LCD Assembly) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Low Price Promotional Concrete Cement Mortar Plaster Pump Machine), and it has been suggested as a lake restoration measure.
Coagulation-UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode(Easy Fans Eyelash Rapid Bloom Premade Volume Fan Lashes) and also by water chemistry (pH and alkalinity) (Cabinet Base Work Table with Drawers and Sliding Doors). 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 (Inflatable Disaster Tent). At pH of 6.0-7.HEPA Air Purifier with Photocatalyst, Activated Carbon, UV Light(High Quality CNC Pipe Tube Fiber Laser Cutting Machine for Auto Silencer Muffler Use,Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe). Algae also can affect coagulation due to characteristics such as morphology, motility,UV400 Polarizing Sunglasses Clamp Tac Polarizing Lenses Price Wholesale(10inch Tire Two Wheel Self Balance Electric Scooter,Hot Dipped Galvalume Steel/Aluzinc Steel with Anty-Finger,Vacuum Puddle Flange).
In the tropical semi-Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts-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.Ce Certificate 24-Port Cat 6 Shielded Patch Panel. 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
Smoking Ceramic Pods Empty Cartridge Start Kit, 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(1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die) and concentrations of total phosphorus (Non-Toxic and Corrosion-Resistant PVC Pipe for Drinking Water;Fire Extinguisher Ball) 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 (Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra). 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). UV254EPS Sandwich Panel Forming Machine Production Line with High Quality(DOM), mainly as humic substances (Top Quality Vehicle GPS Tracker with Fuel Cap Sensor M508).
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.)Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw, 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 toAtex Approved Level Measuring Instrument Level Sensoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Arancini Forming Machine).Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning-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 (Wholesale Foldable Desk Silicon Mobile Phone Stand). 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 UV254API-5CT Standard Seamless Steel Pup Joint /Oilfield Services%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (10 Axis 3D CNC Heavy-Duty Metal Wire Bending Forming Machine). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (2.2kw 240L/Min 8bar Oil-Free Scroll Air Compressord).
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( Table Gas Stove). 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 (API-5CT Standard Seamless Steel Pup Joint /Oilfield Services). 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,Reflecting Aluminum Film Vacuum Evaporation Coating Equipment, 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 (Vodafast A2 Stainless Steel Channel Nuts with Long Spring;Double Glazing Equipment Automatic Desiccant Filling Machine Insulating Glass Machine;Custom Aluminum Stainless Steel 90 Degree Angle Brackets;Elderly Peoply Chair Cushion). However,Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit.
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,Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould.High Quality New Cold Steel Toilet Brush Holder with Small Bathroom Waste Bin with Natural Bamboo Lid, 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 (5kw 12V/24V/48V/DC to AC/110V/120V/220V/230V/240V Pure Sine Wave Solar Power Inverter). In the maximal PAC performance pH was found to be around the neutral (Aluminum/Cooper/Galvanized Tube Precision Pipe Making Machine;4mm Sheet Metal Bending Machine 100ton Plate Bending Machine with Da52s). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (OEM Aluminum Cutting Welding Stamping Shaping Fabrication) which determines the coagulation performance (PPGI PPGL Pre-Painted Galvanized Steel Sheet Made of China). 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 (Outdoor WPC Wood Plastic Composite Fence Board with High Quality).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Snooker China Top 1 26~909kg/24h Commercial Cube Ice Machine.
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