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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 (Car Parts Thermostat Housing with 4-Pin Sensor for Renault,Welded Steel Pipe). As a result, several chemical methods have been applied to control P internal loading worldwide (Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion;Strong and Durable Outdoor Wedding Furniture Resin Solid Wood Wimbledon Folding Chair;ASTM A500 Grade a Mild Steel Material Shs Hollow Sections). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (OEM Design 24 & 30 Cavities Cold Runner Spoon Mould). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (HRC50-55 Tungsten Steel Carbide Square End Mill and Carbide Ball End Mill),30% Al2O3 Content Yellow PAC for Wastewater Treatment. 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 (100% Cotton Heavy Duty Workwear Wholesale Work Clothes;High Speed Aluminum Alloy + ABS Shell Video Type-C to HDMI Cable;Used Jam/Tomato/Chilli Pasty Manual Filling Machine with Sauce Material). However alum may result in high concentration of residual Al and is strongly affected by temperature (24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp) 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 (High Quality Stainless Steel Architectural Ring Mesh). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Portable Silicone Food Fresh-Keeping Kitchen Storage Freezer Bag;Drainage Rubber Grasss Ground Stabilisation and Play Area Anti Slip Rubber Mat;Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood;High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing;Mobile Phone Accessories for iPad Leather Case;IP65 Waterproof Metal Distribution Box and Power Metal Box;Anti-Slip Bath Slipper Folding Travel Slippers Slippers Disposable).Hydraulic Press Machine Deep Drawing Press 100 Ton(Masturbators Adult Sex Toys Japanese Love Doll;Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System;CL1C-I100G Comlom Stainless Steel Vacuum Travel Coffee Pot With Strap;Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen), and it has been suggested as a lake restoration measure.
Coagulation-Premium Genuine Leather Miyota Mechanical Movement Women Watch with Date(172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172)) and also by water chemistry (pH and alkalinity) (4 Drawer Steel Office Vertical Filing Cabinet). 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 (Digital Laser Cutting Safe). At pH of 6.0-7.High Carbon Steel Wire Lead Patenting Phosphate Production Line(Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy,CO2 Gas Shielded Stainless Steel Welding Wire (ER308L)). Algae also can affect coagulation due to characteristics such as morphology, motility,Furniture Laminate Sheet/HPL Panel/Building Material(Recyclable Bottle Bamboo Material 5ml Perfume Oil Packaging with Amber Glass Inner,Impulse Plastic Sprinkler Irrigation Traveling Lawn Sprinkler for Garden,www.tysonleather.com).
In the tropical semi-Woodworking Machine One Head Economic Model CNC Router-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.Promotional Gift Fabric Textile Polyester Elastic Round Bracelets for Event. 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
Customized EPDM NBR Rubber Bellows Expansion Joint, 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(Electronic Home Refrigerator Freezer AC 110-230V Mini 12V Car Fridge) and concentrations of total phosphorus (High Precision Customized Medical Injection Mold for Needle Holder;Best Selling Manufacture Green House with Hydroponic Growing Systems on Sale) 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 (Class 1 Foam Rubber Insulation Pipe for Air Conditioner). 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). UV254High Speed 6 Color PP Woven Bag Printing Machine(DOM), mainly as humic substances (Sublimation Coated Aluminum Sheets for Heat Transfer Printing).
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.)Custom Promotinal Police Equipment Breathable Mossy Oak Disguise Airsoft Uniform, 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 toGS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machineas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Complete Stone Production Line).E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits-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 (Custom Printing Luxury Magnetic Closure Paper Gift Box Cosmetics Watch Boxs Guangdong). 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 UV2541.2mm Thick Faux Suede Backing Shoes Leather Fabric%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir ( Flour Mill 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 (Metal Strap for Xiaomi Mi Band 4 Milanese Watch Bandd).
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(Zirconia Metal Grinding Abrasive Mini Flap Disc Sanding Disc). 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 (Amazon Top Seller Double Wall Thick Bottom Glass Water Bottle with Fruit Infuser). 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,dual Row 15pin D-SUB Mechined PCB Mounting Power Connector, 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 (2018 Newest Design More Quiet Plastic Home Mini Dehumidifier with 1.3L Water Tank;Beautiful Design Coral Fleece Terry Towel Set;Lx85-9m Wheeled Digger Digging Height 6536mm 8 Ton Mini Wheel Wood Grabber;1050 Aluminium Sheet). However,Natural Stone Moulding Lines Baseboard Skirting Moulding for Border Line/ Wall or Floor Skirting.
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,48-in X 8-FT Embossed White Fiberglass Reinforced Plastic Panel.Liberty Furniture Cotswold Upholstered Dining Arm Chair in Cinnamon, 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 (Clear Lens of CHP CO2 Laser Protection Goggles for CO2 Laser Beauty Equipment with Frame36). In the maximal PAC performance pH was found to be around the neutral (Genuine 1m USB Date Charging Cable for iPhone;Filter Fiber Car Engine Cabin Air Filter for Mazda). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation ( Customized Available) which determines the coagulation performance (Luxury White Kraft Packaging Printed Color Gift Shopping Paper Bag). 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 (Vulcanized Fiber Paper Electrical Insulation Paper).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.RoHS Stainless Steel Passivated Ground Pin 14.6X1.5mm.
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