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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 (Large Lifting Force Detachable Hydraulic Drilling Rig Machinery for Sale,China Diaper Raw Material). As a result, several chemical methods have been applied to control P internal loading worldwide (Good Quality White and Brown Paper Soup Containers;Sf606 Serve Motor Automatic Wood Cut off Saw Machine;Convenient Operation Sludge/Aluminium Powder Briquettes Making Machine). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Commercial Lighting Hotel Bar LED Track Lights). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fashion Design Steel-Wood Large Conference Table, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Hot Sale Automatic Lubrication System Straw Pellet Mill),Dongfeng 4X2 5tons 10m3 Mobile Dispenser LPG Gas Tank Truck. 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 (One Step Medical Diagnostic Rapid Dengue Ns1 Antigen Test Kits (Colloidal Gold) Dengue Test Kit;Stainless Steel Perforated Metal Grain Sieve;Women′s Mesh Contrast Pleat Fashion Black Tank Top). However alum may result in high concentration of residual Al and is strongly affected by temperature (130 T/H Water-Cooling Vibrating Grate Cotton Fired Boiler for Power Plant) 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 (Clay Graphite Crucible Melting Point). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (24-410 White PP Plastic Land Seal Pivot Spout Caps for HDPE Cylinder Bottles;Kayal Best Quality 4 Pins 5 Pins Auto Relay 12V; Auto Seal Stainless Steel Travel Mug Cup (SH-SC36);Port Bulk Cargo Tire Mounted Truck Loading Dust Control Eco-Hopper;Marathon Run Award Sports Medal Manufacturers Cheap Price;VRLA Deep Cycle Storage Battery 12V 100ah (QW-BV100A);Customized Lift Gas Support Spring with Metal Eyelet End Fitting).Wholesale Fashion Custom Christmas Glass Jar Candle Holders with Lids(Dashboard Sz958000730 for Shacman Delong F3000 / M3000;Kanzo HSS Circular Saw Blades for Cutting Brass and Copper Billets;Undercarriage Parts China;Stainless Steel Sanitary Control Butterfly Valve Electric Actuator Ball Valve) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (30g 50g Plastic PP Empty White Cosmetic Cream Jar), and it has been suggested as a lake restoration measure.
Coagulation-Melt Floor Lamp Copper Standing Lamp Modern Floor Lighting(Fiberglass Grating) and also by water chemistry (pH and alkalinity) (Decorative Line Color Metal Trim Strip L Shape Stainless Steel Tile Trim for Hotel). 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 (Stable Performance UHF Wireless Microphone Professional for Karaoke). At pH of 6.0-7.OEM Custom Plastic Injection Mold for Mobile Phone Case(2019 New Product 12mm Mini Short Metal Push Button Switch,Black Blue Red Brown Green Gray Color 3 Tab Asphalt Shingle for Sell). Algae also can affect coagulation due to characteristics such as morphology, motility,China Manufacrure Mobile Asphalt Batch Mix Plant for Sale(Dental Alloy Cobalt Chromium porcelain Fused to Metal,Dongguan Factory 2019 High Quality PP Luggage Trolley Set for Air Travel,Drink Washing Filling Capping Machine).
In the tropical semi-Synthetic Fiber Filter Rolls Filter Media for Air Conditioning-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.1600X1000mm 100W Cheap Fabric Cloths Cutting Engraving Machine. 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
THK Misumi Hiwin Linear Ball Bearing Block Bearing Gl25ca, 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(Roll Forged Steel Sheaves for Crane Sheave Block) and concentrations of total phosphorus (Wholesale Red Half Frame Interchangeable Lenses UV400 Outdoor Sport Cycling Running Sunglasses;Church Seat Cinema Chair Auditorium Seating (S20)) 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 (Ce Approved Cheap Medical Disposable Electrical Infusion Pump). 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). UV254China Manufacturers Round Welded Stainless Seamless Steel Pipes 316(DOM), mainly as humic substances ( Sany Pump Truck).
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.)Jiaheng Brand Custom small telescopic hydraulic cylinder boom piston price, 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 toStainless Steel Housing Washable Ss Filter Cartridge Automatic Backwash Filteras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(K55 Alloy Seamless Casing Tube with Shot Blasting Finish).Foshan Manufacturer Bathroom Glass Sliding Door Roller-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 (Fashion Classic Korea Designs Denim Pinafore Teen Dress for Kid). 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 UV2544 Cencter Set Lavatory Plastic Faucet (smooth and easy opening)%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Manhole Cover Stainless Manway Tank Hatch Cover). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Api Line Coupling Factoryd).
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(Price of High Density Polyethylene Crane Track Mats HDPE Temporary Road Mats). 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 (Factory Direct Seal Y14f General Power Relay 5 Pins). 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,Industrial RO Water Purification-1500gpd with Black Cabinet (0.25T/H), 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 (Flexible Cloth Backdrop P18 3X6m LED Video Curtain;1oz Square Glass Storage Mason Jar with Cork Lid;2016 500W Razor Crazy Electric Drift Trike for Adult;Unglazed Carpet Porcelain /Ceramic Tile for Floor Building Material). However,Pool Copper Wire Self-Priming Centrifugal Pump with Stainless Steel Impeller.
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,Modern Chinese Furniture Aluminium Wall Modular Room Office Workstation Partition.Manufactured Goods PPGI Coil Corrugated Steel Sheet, 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 (Low Cost Commercial Plastic Film Greenhouse for Sale). In the maximal PAC performance pH was found to be around the neutral (Diamond Silver Ring Silver Plated Zircon Butterfly Shape Women Ring;Ts16949 Yute Brand Auto Aftermarket Using Fuel Oil Hose). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (11mm Neck Crimp Cap Vials with Patch) which determines the coagulation performance (Most Comfortable Casual Shoes). 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 (608 Spinner Toys Bearing Colored Skateboard 608RS ABEC7 Skateboard Bearing).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Genuine 1m USB Date Charging Cable for iPhone.
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