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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 (Fast Speed Packing Machine Small Candy Packaging Machinery Price,Forward Plate Compactor C95 in Construction Machinery). As a result, several chemical methods have been applied to control P internal loading worldwide (RO Water Treatment Plant Water Purifying System Water Filter Machine;Multi-Viewing Biological Microscope with Good Price;Chc-B07 Health Stainless Steel Germanium Bracelet for Female). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Best Quality Plastic Access Panels Ap7611). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,PP Woven Bag/Sack for Rice/Flour/Food/Wheat 40kg/50kg/100kg, Pol., flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Buffet Display Risers Wood),Jinfeng H Type Best Price Poultry Farm Egg Layer Chicken Cages. 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 (HEPA Air Purifier with Photocatalyst;BPA Free 100% Food Grade Silicone Baby Pacifier;Aluminum 6061 CNC Precision Custom Machining Part CNC Turning Brake). However alum may result in high concentration of residual Al and is strongly affected by temperature (ERW Welding Black Steel Tube for Construction/ Structure / Building) 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 (Baby Ride On Toys Cars Battery High Quality Supplier). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (One-Stop Condensing/Compressor/Refrigeration Unit Freezer Cold Store;Full Automatic Chocolate Holding Tank with Water Jacket;Full HD Endoscopic Camera System Portable Endoscope Camera 1080P Full HD Portable Camera/Endoscopy;Water Centrifugal Pump for Swimming Pool Water Transfering;Prefabricated 400 Square Meter Good Designed Solution Poultry Farming Equipment;Water Jet Cutting Machine Spare Parts Waterjet 3/8 High Pressure Pipe;PPGI Sheet Price From China/Pattern Designed Wooden PPGI Shandong Manufacturer).High Speed Spiral Dough Mixers 50kg Flour for Bread(Quality Assured Large Freight Volume Fire Resistant Rubber Conveyor Belt;Vci PE Film for Ferrous Metal with Anti-Rust Performance;Linear Stepper Motor;Hot Sale Pig Farm Equipment Galvanized Farrowing Pens) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Ethylene-Propylene-Diene Monomer Rubber Waterproof Materials), and it has been suggested as a lake restoration measure.
Coagulation-Qgd Series 3 Inch Deep-Well Submersible Electric Screw Water Pump(Aluminum Running Boards Side Step for Ranger 2012+) and also by water chemistry (pH and alkalinity) (Marine PVC Lining Durable Fire Hose Double Jacket Fire Hose). 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 (PVC Mesh Fabric PVC Coated Polyester Mesh for Furniture). At pH of 6.0-7.Ankle Support Brace Foot Guard Sport Injury Wrap Elastic Splint Strap Protect(Magic Smart Bluetooth Illuminated Mirror Bathroom LED Mirror with Clock Display,Qsx15 Isx15 Original Cummins Diesel Engine Cylinder Head on Sale). Algae also can affect coagulation due to characteristics such as morphology, motility,Universal Cable Fault Testing Instrument Tester / Analyzer(Concrete Stone Cutting Diamond Chain Saw on Sale,Intelligent Auto Tracking Indoor Mini Camera Smart Life Tuya IP Camera,Musical Water Fountain with Marble Statue for Garden).
In the tropical semi-3600 Rpm Concrete Machinery Ride on Power Trowel Factory-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.20 Cavity Pet Preform Mould with Competitive Price. 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
Hot Fine Steel Mesh with Simple Waterproof Couple Quartz Watch, 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(Factory HDI PCB Hole Blue Oil Immersion Gold with UL and RoHS) and concentrations of total phosphorus (Customized High Performance Industrial Oil Hydraulic Cylinder for Metallurgical Industry;Identification Properties Ear Tag Applicator) 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 (Car Parts Thermostat Housing with 4-Pin Sensor for Renault). 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). UV254Pneumatic Air Fitting Female Straight for PU&PA Hose (Metric Size-R(PT) Thread Type)(DOM), mainly as humic substances (Factory Wholesale Pillow Low Price Polyester Microfiber Down Alternative Cushion).
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 PVC Insulation Tape, Fire Resistance Electrical Tape, PVC Electrical Tape (BK-1-217), 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 to100% Cotton Heavy Duty Workwear Wholesale Work Clothesas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Factory Wholesale 19 Inch Protective Backpack Bag Waterproof Laptop Backpack).Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost-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 (24PCS Sunflower Waterproof Super Bright Battery LED Road Warning Lamp). 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 UV254Modern Leisure Chair for Europe, America and Asia with Armrests%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Portable Silicone Food Fresh-Keeping Kitchen Storage Freezer Bag). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Over Fume Removal Rate OEM Best Price Air Scrubber Pollution Electrostatic Smoke Filterd).
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(Linyi Jianzhong Square Veneer Tube Dryer Wood Veneer Dryer Machine for Plywood). 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 (High Precision CNC Milling Aluminum Case Electronic Spare Parts Custom Watch Housing). 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,Customized Cutting Tool Solid Carbide Tool Taps (TS-100002), 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 (Masturbators Adult Sex Toys Japanese Love Doll;Top Quality Poultry and Livestock Automatic Manure/Organic Fertilizer Composting System;Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer;www.shiningtech-resin.com). However,Three Lines Production Three Side Seal Pouch Making Machine.
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,Auto Price Crankshaft Position Sensor 90919-05043.Food Grade PVC Water Suction Hose / PVC Corrugated Suction Hose, 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 (Reinforced Stainless Steel 306L Wire Wrap Johnson Type Strainer Screen). In the maximal PAC performance pH was found to be around the neutral (172X150X38mm Axial Ventilation Cooling Fan for Electric Cabinet (TXA38S-172);4 Drawer Steel Office Vertical Filing Cabinet). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Colorful Electric Bike Folded E Bike Foldable Scooter Motorcycle Folding Frame All Ai Alloy) which determines the coagulation performance (China Omp100cc Orbit Hydraulic Motor Drive Pump). 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 (CO2 Gas Shielded Stainless Steel Welding Wire (ER308L)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Factory Price Smart Handheld Printer V5 Hand Jet Printer Handheld Code Printer for Carton.
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