Research and application of in-situ control technology for sediment rehabilitation in eutrophic water bodies

2012 ◽  
Vol 65 (7) ◽  
pp. 1190-1199 ◽  
Author(s):  
Bo Liu ◽  
Xuegong Liu ◽  
Jie Yang ◽  
David E. J. Garman ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Algal Growth ◽  
Bentonite Clay ◽  
Field Trials ◽  
Application Rate ◽  
Control Technology ◽  
Overlying Water ◽  
P Release ◽  
In Situ Control ◽  
Limiting Nutrient

Phosphorus (P) is often the limiting nutrient for algal growth, and P in sediments can be released under suitable conditions. To control P release, in-situ control technology with lanthanum (La) modified bentonite clay (Phoslock®) was proposed and its effectiveness was tested and evaluated both in laboratory and field trials. The results of static and dynamic simulation experiments under different environmental conditions showed that with the application rate of Phoslock® at 0.5 kg/m2, the orthophosphate (PO4-P) concentration of the overlying water decreased to a low level (≤0.02 mg/L) within 10 days. Even under anaerobic and high pH (pH = 9.0) conditions, the phosphate release suppression efficiency reached 98.3%, and the P-release rate was −8.20 mg/m2 d (negative value indicates P adsorption by Phoslock®). The monitoring data of the field sediments rehabilitation project were consistent with the results achieved in laboratory experiments, thus showing that the application of Phoslock® could inhibit the internal P release effectively.

Study on Phosphorus Release from Sediment Control by In Situ Control Technology

2011 ◽  
Vol 374-377 ◽  
pp. 899-904
Author(s):  
Li Jun Bi ◽  
Jing Yang ◽  
Shi Quan Sun
Keyword(s):  
Dissolved Oxygen ◽  
Calcium Nitrate ◽  
Aerobic Condition ◽  
Phosphorus Release ◽  
Hydrodynamic Condition ◽  
Control Technology ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
In Situ Control

This paper test to processing lakes sediment by three kinds of in-situ control technology which including aeration, zeolite capping and calcium nitrate in situ treatments, and it study the influence of phosphorus release from sediment. The test results showed: (1) under anaerobic conditions, the phosphorus release content is as 4.26 times as it under aerobic conditions. Under aerobic condition (dissolved oxygen saturation ≥ 20%), the Dissolved oxygen is not important for phosphorus release in sediments.（2）zeolite capping can effectively control the phosphorus release from sediment, but Dissolved oxygen is important for that. Under dynamic condition, the phosphorus release content is stability.（3）Under aerobic conditions or anaerobic conditions, calcium nitrate in situ treatments can effectively control the phosphorus release from sediment. Under aerobic conditions, the phosphorus release content reduce by 53.6%.Under anaerobic conditions, it reduce by 83.4%.(4) The control effects of the phosphorus release content by three kinds of in-situ control technology was followed: under anaerobic condition, calcium nitrate in-situ treatment > zeolite capping> untreated; and under aerobic condition, calcium nitrate in-situ treatment > zeolite capping > aeration ≥ untreated; and under hydrodynamic condition, calcium nitrate in-situ treatment >zeolite coverage>zeolite capping> aeration >untreated.

scholarly journals Analysis of Saturation Risk in Sprinkler Irrigation: Case of Cherfech Irrigation Perimeter in Tunisia

2018 ◽  
Vol 10 (2) ◽  
pp. 130
Author(s):  
Samir Yacoubi ◽  
Adel Slatni ◽  
Khemaies Zayani
Keyword(s):  
Sprinkler Irrigation ◽  
Pressure Head ◽  
Field Trials ◽  
Application Rate ◽  
Wetting Front ◽  
Saturated Water Content ◽  
M 12 ◽  
Disc Infiltrometer ◽  
Good Agreement

This study is targeted to the assessment of the saturation risk in sprinkler irrigation. For this purpose, in situ field trials were carried out to infer the saturated hydraulic conductivity (Ks) and sorptivity (S) using the disc infiltrometer method. Since the measured values of Ks are very close to prescribed application rate, caution is required. In a first step, the pressure head at the wetting front (hf) and the useful porosity (θs – θi) are assumed to be constant. Thus, the logarithmic derivation of the sorptivity provides a relation between relative variations of S and Ks. The ponding time (Ts) is estimated from Green and Ampt (1911) and Philip (1957b) infiltration equations. The risk of saturation is deemed to be inexistent inasmuch as simulated values of Ts are greater than the irrigation times practiced in the zone. In a second step, the values of the pressure head at the wetting front and saturated water content were assumed to be variable with soil texture. Simulations of the ponding time were carried out based on Rawls and al. (1981) data. For the recommended sprinkler spacing in the Cherfech perimeter (12 m × 12 m), the simulations show a good agreement between Ts values generated from Green and Ampt and Philip equations for Ks ranging from 1.5 to 6 mm/h. Moreover, it was established that saturation risk due to a gradual texture variation is virtually inexistent in the conditions prevailing in Cherfech perimeter.

scholarly journals Electrochemical bubble generation via hydrazine oxidation for the in situ control of an electrodeposited conducting polymer micro/-nanostructure

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 11020-11025
Author(s):  
David Possetto ◽  
Luciana Fernández ◽  
Gabriela Marzari ◽  
Fernando Fungo
Keyword(s):  
Conducting Polymer ◽  
Electrochemical Method ◽  
Bubble Generation ◽  
Hydrazine Oxidation ◽  
In Situ Control

An electrochemical method to manipulate the size and density of electrodeposited polypyrrole structures at the micro-nanoscale by the discharge of hydrazine.

In-situ control of on-chip angstrom gaps, atomic switches, and molecular junctions by light irradiation

Nano Today ◽  
2021 ◽  
Vol 39 ◽  
pp. 101226
Author(s):  
Surong Zhang ◽  
Chenyang Guo ◽  
Lifa Ni ◽  
Kerstin M. Hans ◽  
Weiqiang Zhang ◽  
...  
Keyword(s):  
Molecular Junctions ◽  
Light Irradiation ◽  
In Situ Control ◽  
On Chip

scholarly journals Integrative analysis of <i>Geobacter</i> spp. and sulfate-reducing bacteria during uranium bioremediation

2012 ◽  
Vol 9 (3) ◽  
pp. 1033-1040 ◽  
Author(s):  
M. Barlett ◽  
K. Zhuang ◽  
R. Mahadevan ◽  
D. Lovley
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Field Trials ◽  
Second Phase ◽  
Sulfate Reducing ◽  
Organic Electron ◽  
Poor Understanding ◽  
Key Factor ◽  
Reducing Bacteria ◽  
The Impact

Abstract. Enhancing microbial U(VI) reduction with the addition of organic electron donors is a promising strategy for immobilizing uranium in contaminated groundwaters, but has yet to be optimized because of a poor understanding of the factors controlling the growth of various microbial communities during bioremediation. In previous field trials in which acetate was added to the subsurface, there were two distinct phases: an initial phase in which acetate-oxidizing, U(VI)-reducing Geobacter predominated and U(VI) was effectively reduced and a second phase in which acetate-oxidizing sulfate reducing bacteria (SRB) predominated and U(VI) reduction was poor. The interaction of Geobacter and SRB was investigated both in sediment incubations that mimicked in situ bioremediation and with in silico metabolic modeling. In sediment incubations, Geobacter grew quickly but then declined in numbers as the microbially reducible Fe(III) was depleted whereas the SRB grow more slowly and reached dominance after 30–40 days. Modeling predicted a similar outcome. Additional modeling in which the relative initial percentages of the Geobacter and SRB were varied indicated that there was little to no competitive interaction between Geobacter and SRB when acetate was abundant. Further simulations suggested that the addition of Fe(III) would revive the Geobacter, but have little to no effect on the SRB. This result was confirmed experimentally. The results demonstrate that it is possible to predict the impact of amendments on important components of the subsurface microbial community during groundwater bioremediation. The finding that Fe(III) availability, rather than competition with SRB, is the key factor limiting the activity of Geobacter during in situ uranium bioremediation will aid in the design of improved uranium bioremediation strategies.

scholarly journals In Situ control and modification of the probe magnetization state for accurate magnetic force microscopy

2017 ◽  
Author(s):  
Livia Angeloni ◽  
Daniele Passeri ◽  
Marco Natali ◽  
Melania Reggente ◽  
Emanuele Anelli ◽  
...  
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Force Microscopy ◽  
Magnetization State ◽  
In Situ Control

scholarly journals Genotype selection and addition of fertilizer increases grain yield in upland rice in Suriname

2017 ◽  
Vol 47 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Adriano Stephan NASCENTE ◽  
Ruby KROMOCARDI
Keyword(s):  
Grain Yield ◽  
Management Practices ◽  
Upland Rice ◽  
Block Design ◽  
Field Trials ◽  
Application Rate ◽  
Rice Grain ◽  
Rice Varieties ◽  
Local Conditions ◽  
Randomized Block Design

ABSTRACT The upland rice farmers in Suriname use local varieties and low level technologies in the field. As a result, the upland rice grain yield is low, at about 1 000 kg ha-1. Our objective was to evaluate the use of upland rice cultivars from Suriname and Brazil, and the effect of nitrogen, N, phosphorus, P, and potassium, K, fertilizers on cultivation variables. We undertook four field trials in the Victoria Area, in the Brokopondo District, using a randomized block design each with four replications. The most productive rice varieties were BRS Esmeralda (grain yield 2 903 kg ha-1) and BRS Sertaneja (2 802 kg ha-1). The highest grain yield of 2 620 kg ha-1 was achieved with a top dressing application of 76.41 kg N ha-1 20 days after sowing. For P, the highest grain yield of 3 085 kg ha-1 was achieved with application of 98.06 kg ha-1 P2O5 applied at sowing. An application rate of 31.45 kg ha-1 of K2O at sowing achieved the highest grain yield of 2 952 kg ha-1. Together, these application rates of N, P and K resulted in rice grain yield of about 3 000 kg ha-1, which is three times greater than the national average for upland rice. We demonstrate that the use of improved rice varieties matched to the local conditions, and application of appropriate fertilizers, are management practices that can result in significant increases in rice grain yield in Suriname.

Electricity generation through a photo sediment microbial fuel cell using algae at the cathode

2017 ◽  
Vol 76 (12) ◽  
pp. 3269-3277 ◽  
Author(s):  
B. Neethu ◽  
M. M. Ghangrekar
Keyword(s):  
Power Generation ◽  
Organic Matter ◽  
Microbial Fuel Cells ◽  
Carbon Capture ◽  
Algal Growth ◽  
Oxygen Demand ◽  
Sediment Organic Matter ◽  
Overlying Water ◽  
Organic Matter Removal ◽  
Removal Efficiencies

Abstract Sediment microbial fuel cells (SMFCs) are bio-electrochemical devices generating electricity from redox gradients occurring across the sediment–water interface. Sediment microbial carbon-capture cell (SMCC), a modified SMFC, uses algae grown in the overlying water of sediment and is considered as a promising system for power generation along with algal cultivation. In this study, the performance of SMCC and SMFC was evaluated in terms of power generation, dissolved oxygen variations, sediment organic matter removal and algal growth. SMCC gave a maximum power density of 22.19 mW/m2, which was 3.65 times higher than the SMFC operated under similar conditions. Sediment organic matter removal efficiencies of 77.6 ± 2.1% and 61.0 ± 1.3% were obtained in SMCC and SMFC, respectively. With presence of algae at the cathode, a maximum chemical oxygen demand and total nitrogen removal efficiencies of 63.3 ± 2.3% (8th day) and 81.6 ± 1.2% (10th day), respectively, were observed. The system appears to be favorable from a resources utilization perspective as it does not depend on external aeration or membranes and utilizes algae and organic matter present in sediment for power generation. Thus, SMCC has proven its applicability for installation in an existing oxidation pond for sediment remediation, algae growth, carbon conversion and power generation, simultaneously.

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