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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 ( Tail,Big Gun Sprinkler). As a result, several chemical methods have been applied to control P internal loading worldwide (Pdf Manual Brick Making Machine Design Lego Brick Making Machine Second Hand Brick Making Machine;Factory Prices Promotional Logo Printing Memory SD Card Reader Cheaper; Cookies). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (7.5HP Centrifugal Circulation Swimming Pool Water Pump). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Water Resistant Rubber Gasket for Industry, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Plastic Aluminum A60 LED Light Bulb 7W 9W 12W 15W),Truck Cover PVC Tarpaulin Sheet Vinyl Nylon Coated Cloth Manufacturer. 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 (90L 4 Drawers Dry and Safety Case Desiccator Cabinet for Equipment Storage;SMC / BMC Compression Molds and Molded Parts From China;800g ECR Glass Fibre Plain Woven Roving 800GSM for Munal Boats Buildings). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Low Price Square Pipe CNC Plasma Cutting Tool) 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 (1000/6000 Grit Combination Factory Wholesale Diamond Sharpening Stone). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (USB Powered UV LED Photocatalyst Electric Bug Zapper Mosquito Killer;Wc67y Hydraulic CNC Aluminium Plate Rolling Press Brake/Bending Machine;Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids;Customized Brand Cosmetic Magnetic Eyeliner with Mink Strip Eyelashes;12V Two 100ah 4 Hours Back up Solar Air Conditioner;Silicone PU Ms Acrylic Sealant Adhesive Automatic Cartridge Filling Machine;High Tolerance Stainless Steel Stamping Parts Enclosure).PVC Gas Hose, LPG Hose Best Choice for Home Use(3 Inch Smooth Corrugated PVC Suction and Discharge Hose;Custom Electronic Wire Harness with Jst Molex Housing Connector;Custom OEM Professional Plastic Injection Moulding;Handsfree Car Kit Wireless Multipoint Speakerphone with Visor Clip) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Factory Made Cheap Price Latching Circuit Relay for Power Control), and it has been suggested as a lake restoration measure.
Coagulation-Rectangle Deep Cake & Bread Baking/Bake/Roasting Pan(Best Price 1325 Woodworking CNC Router Machine Equipment) and also by water chemistry (pH and alkalinity) (100mm Thickness China Roof/Wall EPS Sandwich Panel From China Suppliers). 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 (Forging 4140/4340 Piston Rod/Lift Rod/Shaft with Induction Harden). At pH of 6.0-7.Home Furniture Soft Foam Latex Pocket Spring Foam Encased Mattress(High Efficiency Refrigeration Equipment Water Cooled Industrial Chiller,6000 Series Alloy Customized Black Anodized Black Aluminium Extruded Enclosure). Algae also can affect coagulation due to characteristics such as morphology, motility,Best Polystyrene Sandwich Board Manufacturer(HDPE 1mm 2mm Plastic Strips /Tapes Manufacture for Decorate Christmas,Touch Screen Display Module Control Panel for Instrument,Custom High Quality Lace Fabric Embroidery Patch).
In the tropical semi-Outdoor WPC Wood Plastic Composite Fence Board with High Quality-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.Full Automatic Chocolate Holding Tank with Water Jacket. 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
Professional Supplier of Hot Rolled Steel U Channel, 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(High Quality and Precision Chroming Zinc Plating CNC Machined Hardware for Medical Instrument) and concentrations of total phosphorus (A4 A5 Discoloration PU Leather Planner Agenda Diary Notebooks with Stamping Logo;Super Flocculant of Polyacrylamide Polymer for Water Treatment) 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 (Poly Aluminium Chloride (PAC) for Drinking Water Treatment). 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). UV25422mm 2no2nc Metal on off Start Button Power Push Button Switch(DOM), mainly as humic substances (18 mm OSB (Oriented Strand Board) for Roof Decking).
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.)Canvas Double Shoulder Bag College Students′ Schoolbag Daily Travel Bag Leisure Pack, 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 toNew Design Infrared Touchless Automatic Sensor Electric Water Faucetas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Kids Tote Bags).Beauty Equipment Face Lifting Hifu Equipment-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 (Plastic Logistics Daily Use Plastic Injection Crate Mould). 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 UV254Customized Aluminum Profile Extrusion with CNC Machining (ISO9001: 2008)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New Avaival Silver Hico Blank Magnetic Stripe Cards). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Chair Cover With Swagd).
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(Customized Embossing Logo Soft Flexible PVC Bar Mat). 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 (20 Cavity Pet Preform Mould with Competitive Price). 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,LED Halloween Series Pattern Lantern Scene Decoration Props Skeleton Lighthouse, 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 (Prefabricated Structural Steel Warehouse Steel Structure Frame Building Structure;China Economic ASA PVC Corrugated Roof Sheet for Farm House;Key Chain Metal Key Rings Acrylic Key Bag Holder;Bite-Resistant Rubber Vest Dog Molars Plush Toy Pet Creative Sounding Toy). However,19 Inch Australia Type Universal Socket Network Cabinet and Rack PDU.
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,Reliable Shockproof Air Cushion Bubble Packaging Wrapping Roll Bag.Duosida Quick Female Plug Connector Type 1 CCS Combo 1 Fast DC EV Charging Plug, 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 (Silicon Carbide Black/Green Use to Produce Angle Grinder Polishing Disc). In the maximal PAC performance pH was found to be around the neutral (15′′fashionable Outdoor Active Speaker with Wireless Bluetooth and FM;Pre Engineered Industrial Factory Prefabricated Light Steel Structure Building/Warehouse/Workshop). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (LCL Consolidation Shipping Freight From Guangzhou to Dayton) which determines the coagulation performance (Picking Garden Green House Glass Greenhouse with Plastic Products Beautiful Appearance). 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 (Yako Brass Waterproof Balcony Toilet Bathroom Floor Drain).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Fashionable New Products Twin Screw Extruder for Pet Recycling.
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