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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 (Wholesale Custom Color Beauty DIY Face Mask Spatula Set Plastic Mini Facial Cosmetic Spatula,Tk-475 Copier Toner). As a result, several chemical methods have been applied to control P internal loading worldwide (Cartoon Design Decorative PVC Sheet for Wall Panel Moulding; Skin Care;3003 3004 3005 Aluminium Circles for Foil Pans with Lids). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (All Round Inflatable Stand up Paddle Boards for Surfing). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Pin-Barrel Rubber Sheet Lining Extruder System Machine Production Manufacturing Line, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Nail Ornaments Turntable Wholesale Bagged Pearl Ab Color 4mm 2mm Nail Turntable Jewelry),Sheet Metal Stamping Galvanized Steel Panel and Frame. 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 (Fiberglass FRP Sandwich Panel for Insulation Truck Body Construction;Bottles Juice Glass Bottles Liquid Filling Line Beverage Processing Machinery;Carbon Stick Welding Electrodes E6013&E7018 Stone Bridge Brand). However alum may result in high concentration of residual Al and is strongly affected by temperature (Compact Laminate Kids Urinal Screen with Good Price) 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 (Doser Unit). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Modern New Design Red Back Massage Table Pedicure Chair;Scarifier Loosener Ripper Horizontal Rotary Cultivator Tiller;Factory Customized Outdoor Gate Decoration Marble Antique Pillar Mcy-63;New Product PVC Insulation Tape;Moisturizer Powder Form Cosmetic Grade Hyaluronic Acid;GM320 Digital Infrared Thermometer Non Contact Infrared Thermometer IR Laser Point Gun -50~330 Degree;Food Grade Clamped Tubular Sight Glass in Stainless Steel).Patterned Shoulder Nozzle Aluminum Tube for Glue/Medical Ointment Packaging(Professional Stage Lighting 7PCS 4in1 LED Flat PAR Lights;57-5 Micron Micro Powder Mill Pulverizer Grinding Plant;Door Core Lvl;Yarmax Manufacturer! Hot Sale! Top Sale Open Frame Electric Start Diesel Generator 5.8kVA Ym9500e) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wholesale Fashion Custom Round Neck Mens Tshirts Plain Tshirts for Print), and it has been suggested as a lake restoration measure.
Coagulation-Infrared Thermometer, Thermometer, Non-Contact Thermometer Gt750(Best Selling Mirror Aluminum Sheet for LED Lights and Decorations etc.) and also by water chemistry (pH and alkalinity) (Cast Iron Housing 380V AC 3kw 3Wq Submersible Sewage Water Pump). 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 (Easy Installation Aluminum Alloy Solar PV Accessories for Tile Hook Kites). At pH of 6.0-7.UHP Dia. 350mm (14inch) 1800mm (72inch) 3tpi Graphite Electrode(Large Industrial Ceiling Fan with External Rotor Motor Drive,High Quality Non-Standard Metal Components Precision Machining Mold Parts). Algae also can affect coagulation due to characteristics such as morphology, motility,HEPA Air Purifier with Photocatalyst, Activated Carbon, UV Light(Manufacturing High Precision Ce Horizontal Cutting Band Metal Sawing Machine,800W/55ah Luxury Four Wheels Electric Mobility Scooter with LED Lights,Hydraulic Ripper For Excavator).
In the tropical semi-UV400 Polarizing Sunglasses Clamp Tac Polarizing Lenses Price Wholesale-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.Aluminium Foil Cup Lids Metal Stamping Parts/Deep Drawing Parts. 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
Ce Certificate 24-Port Cat 6 Shielded Patch Panel, 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(Mini Hug Converter Micro 2.0 Micro USB Adapter for Reader Connector) and concentrations of total phosphorus (PP Surface Self Adheisve Roof Underlayment;Alkali-Resistant Fiberglass Net 4X7mm) 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 (Aluminum Die Casting Mould Industrial Fittings Auto Parts Aluminum CNC Processing). 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). UV254Smoking Ceramic Pods Empty Cartridge Start Kit(DOM), mainly as humic substances (Jbz-22D Automatic High Speed Paper Cup Forming Machine).
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.)EPS Sandwich Panel Forming Machine Production Line with High Quality, 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 toWood Based Powdered Norit Activated Carbon Priceas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Battery Charger).Compressor Heat Exchanger Heat Exchanger for Water to Air with 2kw-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 ( 1 High Alumina Ceramic Ball with High Quality). 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 UV254Gy-50/1000 High Pressure Cleaning Equipment for Pipe Cleaning%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Left Hand Drive a-Pillar Rocker Switch Pod Panel Kit for Jeep Wrangler Jk 07-17). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (925 Sterling Silver Ringsd).
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(High Quality Wooden Cabinet Design Shoe Display Unit for Shop). 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 (Customized Easy Installation Modern Luxury Container House). 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,API-5CT Standard Seamless Steel Pup Joint /Oilfield Services, 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 (Organice Ball Fertilizer Granulation Machine;Hotel Waffle Slipper From China Supplier (DPF2437);USB a to Lightning Quick Charge Data Cable;Closed Body Turnbuckle Fittings). However,Reflecting Aluminum Film Vacuum Evaporation Coating Equipment.
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,Newborn Down Snowsuit Hooded Pajamas Cartoon Jumpsuit.Paint Bucket Plastic Injection Mold Design Manufacture Chemicals Container Mould, 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 (Outdoor Fitness Equipment Gym Chilren′s Teeterboard). In the maximal PAC performance pH was found to be around the neutral (Ruipai High Quality Plastic Recycling Extruder;Basket Filter Made of Standard Basket and Slanted Basket). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (40 Cbm Fly Ash/Cement/Lime/Grain/Farina/Metal/Mineral Powder Material Tanker Semi Trailer) which determines the coagulation performance (Portable Silicone Water Bottle Coffee Bottle Outdoor Travel Drinking Sport Drink Kettle). 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 (Warehouse Storage Industry Rack Mezzanine Floor Platform).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Eco-Friendly Material Restaurant Furniture Metal Stainless Steel Desk Leg Table Base Legs (TB-04).
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