Partial Control of a Continuous Bioreactor: Application to an Anaerobic System for Heavy Metal Removal

This work presents a control strategy for a continuous bioreactor for heavy metal removal. For this aim, regulation of the sulfate concentration, which is considered the measured and controlled state variable, allowed diminishing the cadmium concentration in the bioreactor, where the corresponding controller was designed via nonlinear bounded function. Furthermore, a nonlinear controllability analysis was done, which proved the closed-loop instability of the inner or uncontrolled dynamics of the bioreactor. A mathematical model, experimentally corroborated for cadmium removal, was employed as a benchmark for the proposed controller. Numerical experiments clearly illustrated the successful implementation of this methodology; therefore, cadmium removal amounted to more than 99%, when the initial cadmium concentration was up to 170 mg/L in continuous operating mode.

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Comparative Evaluation of Soluble and Insoluble Xanthate Process for Heavy Metal Removal from Wastewaters

Water Science & Technology ◽

10.2166/wst.1992.0404 ◽

1992 ◽

Vol 26 (1-2) ◽

pp. 237-246 ◽

Cited By ~ 24

Author(s):

V. Tare ◽

S. Chaudhari ◽

M. Jawed

Keyword(s):

Heavy Metal ◽

Comparative Evaluation ◽

Corn Starch ◽

Metal Removal ◽

Heavy Metal Removal ◽

Soluble Starch ◽

Aqueous Systems ◽

Cadmium Removal ◽

Removal Capacity ◽

Ph Range

Insoluble (ISX) and soluble starch xanthate (SSX) were synthesized in the laboratory from corn starch, and were used for metal [Cd(II), Cu(II) and Cr(VI)] removal from aqueous systems. Results indicate that soluble as well as insoluble xanthate processes are capable of meeting various effluent disposal standards. Metal removal by both the processes is maximum in the pH range 4 to 5. Mechanism of Cu(I I)-xanthate and Cr(VI)-xanthate interaction is also discussed. From overall comparison of the two processes it appears that theinsoluble xanthate process has an edge over the solublexanthate process in terms of metal removal capacity, reliability and ease of operation, particularly for cadmium removal. However, soluble xanthate process appears to be relatively less expensive compared to insoluble xanthate.

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Can Microbially Induced Calcite Precipitation (MICP) through a Ureolytic Pathway Be Successfully Applied for Removing Heavy Metals from Wastewaters?

Crystals ◽

10.3390/cryst8110438 ◽

2018 ◽

Vol 8 (11) ◽

pp. 438 ◽

Cited By ~ 12

Author(s):

Álvaro Torres-Aravena ◽

Carla Duarte-Nass ◽

Laura Azócar ◽

Rodrigo Mella-Herrera ◽

Mariella Rivas ◽

...

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Contaminated Soils ◽

Metal Removal ◽

Metal Tolerance ◽

Heavy Metal Removal ◽

Heavy Metal Tolerance ◽

Successful Implementation ◽

Calcite Precipitation ◽

Microbially Induced Calcite Precipitation

Microbially induced calcite precipitation (MICP) through a ureolytic pathway is a process that promotes calcite precipitation as a result of the urease enzymatic activity of several microorganisms. It has been studied for different technological applications, such as soil bio-consolidation, bio-cementation, CO2 sequestration, among others. Recently, this process has been proposed as a possible process for removing heavy metals from contaminated soils. However, no research has been reported dealing with the MICP process for heavy metal removal from wastewater/waters. This (re)view proposes to consider to such possibility. The main characteristics of MICP are presented and discussed. The precipitation of heavy metals contained in wastewaters/waters via MICP is exanimated based on process characteristics. Moreover, challenges for its successful implementation are discussed, such as the heavy metal tolerance of inoculum, ammonium release as product of urea hydrolysis, and so on. A semi-continuous operation in two steps (cell growth and bio-precipitation) is proposed. Finally, the wastewater from some typical industries releasing heavy metals are examined, discussing the technical barriers and feasibility.

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