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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 (1 Ton Biomass Pellet Paddy Rice Wood Chips Fired Laundry Steam Boiler,Paper Plate). As a result, several chemical methods have been applied to control P internal loading worldwide (Wns Gas Oil Fired Boiler Hot Water Heating System;Transparent High Quality Building Glass Curtain Wall From China Suppliers;Flat Compression Injection Mould Die Spring/Standard Coil Spring with Rectangular Section). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (3200kg 20m Cable Portable Manual Hoist Multi-Purpose Wire Rope Pulling Hoist). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hydraulic Control Valve-100A Angular Stable Water Level Valve, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Factory Outlet Giant Inflatable Tiger for Advertising Roof Decoration),Multifunction Universal Testing Equipment Diesel Injecor Pump Test Bench. 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 (Automatic Poultry Farm Equipment High Quality Drinker Cup for Chicken;ACP/ACP Sheet/Aluminum Composite Panel Manufacturer;Yellow Corrugated PE-Al-PE Gas Pipe with Size 16mm to 32mm). However alum may result in high concentration of residual Al and is strongly affected by temperature (New Business Projects Mobile 5D Cinema with High Quality) 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 (4140 Seamless Cylinder Stainless Steel Tube). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (5 Inch Diamond Protected Teeth Blades for Cutting Granite;Custom Your Design Logo Women T Shirt Fashion Cotton Casual Girl Tshirt Basic Ladies T-Shirt;Steel Structure Roofs System TPO Waterproof Membranes;Water Heater Single Head Shrinking Machine;Reverse Engineering Circuit Boards;Co-Extrusion Extruder Single Screw Auxiliary;2019 Unique Design UV Printing Phone Case for Apple iPhone 8).Auto Styling Car Interior Accessories Central Armrest Storage Glove Trau Box for Ranger(Immersion Gold 94V0 Circuit Board Assembly Saving Energy Electrical PCB;Kitchenware 800cc Glass Stainless Steel French Press Mug Portable French Press Coffee Maker;95% Sodium Carboxymethyl Cellulose /CMC for Feed Grade;OEM Customized Design Heat Transfer Print Sports Baseball Cap Manufacturer) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Sun Cover Heat Resistance Shade Privacy Screen), and it has been suggested as a lake restoration measure.
Coagulation-Pillow Type Candy Packing Machine Candy Packaging Machinery Manufacturer(Clear Plastic PVC Window Cmky Full Color Printing Box) and also by water chemistry (pH and alkalinity) (Good Quality Brow Pencil Pencil Private Label Wholesale). 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 (Anti Impact UHMWPE CNC Machined Customized Plastic Parts UHMWPE Parts). At pH of 6.0-7.Aluminium/Brass/Stainless Steel Cam Lock Quick Coupling(Ce RoHS Approval 12W LED Lamp Bulb with Aluminum PBT Plastic,Oeko Certified Down Insert Pillow for 5star Hotel Duck Pillow). Algae also can affect coagulation due to characteristics such as morphology, motility,Wireless Bluetooth Earphones Headsets Stereo Headphone for Sports and Travel(Jingsun off Grid 100kw Solar Power System for Project,RGB Indoor P4 Full Color Creative Flexible LED Display with Nationstar Lamp,Custom Chest Printing Baby Clothes Long Sleeve Organic Cotton T Shirt Girls Tops).
In the tropical semi-100% Cotton Heavy Duty Workwear Wholesale Work Clothes-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 ISO Approved Yiwu Medical Factory Price Plastic Disposable Blood Lancet. 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
5um Metallized Polypropylene Film Single Sided Capacitor Film, 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(Mimaki Jv5/Jv33/Jv300/Ss21/Sb53 Permanent Ink Cartridge Chips) and concentrations of total phosphorus (Solid Surface Stone Table Top Restaurant Black Round Dining Tables;Isolation Gown) 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 (Coolsour Air-Conditioning Compressor Crankcase Silicone Rubber Heating Strip). 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). UV2547 Inch Diamond Double Row Abrasive Grinding Wheels for Stone Polishing(DOM), mainly as humic substances (Chain Rigging Clip U Bolt Saddle Cable Clamp).
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.)M-F1a1 Outdoor Rescue Aluminium Alloy Military Folding Ambulance Stretcher, 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 toSurface Paiting Line UV PU Water Base Spraying Robot Armas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Accounting Sdo Teilar).10 Heads Weigher for Automatic Nuts Dry Dates Bag Packing-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 (Cheap China 2 Inch Wafer Stainless Steel Butterfly Valve). 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 UV254Intelligent Dry-Type Transformer Monitor with Plastic Cover%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (The Best Venlo Type and Multi-Span Glass Greenhouse for Agriculture). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Wholesale 5L Red Cheap Mini Bar Makeup Fridge Mini Coolerd).
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( Construction Pipes Price). 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 (Synthetic Filament Spunbonded and Needlepunched Nonwoven Geotextiles). 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,16 Strings Solar Power Equipment Combiner Box for 1000V DC System, 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 (3-Wheel Motorcycle with 1500W Motor and EEC Certificate;10/30/50ml Single Gourd Shape Amber Essential Oil Cosmetic Glass Dropper Bottle for Mushroom;Hot Sale Vibration Equipment Gear Mootor Vertical Vibrator Motor;Big Capacity Electronic Kettle with Ce and CB Certificate 3.0L). However,Manufacturer C / U-Channel Metal Solar Panel Mounting Brackets PV Mounting Frame Manufacturer.
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,Hot Sale Outdoor Car Carport Shelter with Low Price.Golf Ball Pick-up Ball Retriever Ball Scoop Telescopic up to 5.5m, 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 (Patient Modular Monitor with Wireless Network and Wire Network). In the maximal PAC performance pH was found to be around the neutral (25nm Ys-2.5b1 for Unreeling Hollow Shaft Magnetic Powder Brake;Medical Infusion Pump for Human and Veterinary with Fluid Warmer). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Ce Certificated Acm-60 PTFE Powder Grinding Mill) which determines the coagulation performance (1500W Electric Chopper Wholesale Home Frozen Fish Bone Meat Band Saw Pork Shredding Mincing Machine). 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 (Buildings Materials ASA PVC Roof Tile Roofing Sheet).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.High Quality Prefabricated High Rise Steel Structure Apartments Hotel Building.
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