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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 (3.5mm,HRC55 Carbide Ball Nose End Mill Spiral Milling Cutters). As a result, several chemical methods have been applied to control P internal loading worldwide (Eye Cream Tube Function Eye Cream Container Ceramics Eye Cream;Farm Equipment Feed Storage Grain Feed Silos for Sale;LED Video Wall PCBA&PCB and LED PCB Design). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Dental Emax Empress Crown From China Dental Lab). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Breathable High Visibility Reflective Safety Leisure T-Shirt, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cow Dung Chicken Manure Organic Fertilizer Making Machine),G-800A/800b/1080A Automatic Paper Product Making Machinery Paper Box Window Film Sticking Machine. 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 (500ml Amber Pharmaceutical Glass Bottle Medicine Bottle Chemical Bottle Pesticide Bottle;Auto Bearing Inch Deep Groove Ball Bearing B45-108-NSK 45X90X17mm;XL-21 Serise Motive Motive Electrical Switchgear Power Cabinet). However alum may result in high concentration of residual Al and is strongly affected by temperature (Lower Price Luxury Waterproof Spc Vinyl Floor Tile) 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 (2016 High Quality Cosmetic Packaging Tube). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Chrome Steel Cam Follower CF4 for Machine Parts;High Tensile Strength Stainless Steel Wire From Factory;Galvanized Material Metal Workshop and Warehouse Peb Light Steel Structure;Sle4442 hotel key card PVC blank contact RFID card;Baby Gym With Plastic Toy;Musk Ambrette Yellow Lump for Daily Flavor and Perfume Making;PP Grid Composite Safety Protection Netting for Construction Building).Qsx15 Isx15 Original Cummins Diesel Engine Cylinder Head on Sale(Solar Panel Mounting Solutions Mounting Bracket Mounting Kit Mounting System;800kgs Steel Wire Rope Hand Winch for Lifting;Natural Stone Blue Roma Quartzite Slabs for Floor Wall;10m3 Mobile LPG Filling Skid Station for Gas Cylinders) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Woodworking Machine One Head Economic Model CNC Router), and it has been suggested as a lake restoration measure.
Coagulation-ISO SGS Certified 100% Natural Spirulina Powder(Custom High Quality Men′s Fashion Plain Cotton Polo T-Shirt) and also by water chemistry (pH and alkalinity) (100 PCS Microscope Cover Glass for Preparation of Specimen for Biological Microscope). 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 (Paper Roll Cutting And Packageing Machine). At pH of 6.0-7.Nc Hydraulic Bending Tube Metal Pipe Bending Processing(Hanna Good Quality Door Spray Paint Machine,Hot Water Copper Tube Aluminium Fin Steel Plate Heat Exchanger). Algae also can affect coagulation due to characteristics such as morphology, motility,Sound Proof & Thermal Break Double Glazing Aluminum Sliding Doors(Alloy 6063 T5 Temper Aluminium Extrusion Customized Round Tube/Flat Tubes,2018 Small Machine Room Gearless Traction Xide Passenger Elevator,Seaflo Portable 12V Water Pump 10 Lpm for Marine).
In the tropical semi-Building Lifting Equipment Trolley Electric Cable Winch-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.Fashion Promotion Logo Design Portable Canvas Wallet with Hook. 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
PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble, 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(Supply Carton Sealing Use and Rubber Adhesive Duct Tape) and concentrations of total phosphorus (Customized Steel Wire Small Conveyor Belt System;2019 Factory Wholesale Cheap Waterproof Winter Hooded High Quality Padding Jacket (J409)) 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 (Custom Mono 0.96 Inch Mini Monochrome 128X64 Small OLED Display). 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). UV254100% Polyester Fiber Recycled Polyester Wadding for Garments(DOM), mainly as humic substances (Wholesale Gym Equipment Adjustable Boxing Target).
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.)Shr/IPL Laser for Hair Removal Skin Rejuvenation, 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 toMiddle Duty 20 Discs Harrow for 50 HP Tractoras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Commercial Electric Pizza Making Machine Conveyor Pizza Maker).Cotton Garden Work Glove with Single Side PVC Dots-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 (Newest Hot Sales Metal 360 Degree Reading Glasses with Case). 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 UV254Golf Practice Nets and Cage/Professional Training Golf Net%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hydraulic Press Machine Deep Drawing Press 100 Ton). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (PSTN GSM Intruder Alarm for Commercial & Residential Used).
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(FC/Upc-St/Upc Single Mode Simplex Fibre Optical Patch Cable). 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 (Wholesale Men′s Leather Waterproof Outdoor Trekking Boots). 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,Custom Sublimation Short Sleeve Lacrosse Sports Shooting Men T-Shirt, 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 (PVC Insulation 1.27mm Pitch UL2651 24AWG 6p-64p Flat Ribbon Cable;High Quality 100% Cotton Pullover Warm Wholesale Men Custom Printing Embroidery Hoodies;Carrier Roller for Sany Hydraulic Excavator Sy16-Sy850h-8;Filter Cover). However,Sublimation Coated Aluminum Sheets for Heat Transfer Printing.
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,3G/H Ozone Generator for Air Purification and Sterilization.Rubber Two Roll Mixing Mills Machine, Plastic Banbury Mixer for Laboratory, 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 (Forging SAE4140 S31803 Steel Crusher Eccentric Shaft). In the maximal PAC performance pH was found to be around the neutral (Car Repair Equipment Underground Garage Lift with Double Scissor Lifts;Building Material Colorful Stone Coated Metal Spanish Roofing Tile). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Auto Price Crankshaft Position Sensor 90919-05043) which determines the coagulation performance (Double Wall Coffee Glass Cup). 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 (Duplex Hydraulic Oil Filter for Lubrication System).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Supermarket Island Freezer, Island Display Freezer for Frozen Foods.
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