U.S. flag An official website of the United States government.
Official websites use .gov

A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS

A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

i

Laboratory Sand Column Study of Encapsulated Buffer Release for Potential In Situ pH Control



Details

  • Personal Author:
  • Description:
    Encapsulation technology is being investigated as a method for controlling pH in situ at contaminated groundwater sites where pH may limit remediation of organic contaminants. This study examined the effectiveness of using KH2PO4 buffer encapsulated in a pH-sensitive coating to neutralize pH in laboratory sand columns (1.5-l) under a simulated groundwater flow rate and characterized the pattern of capsule release in the flow-through system. Denitrification was used in the columns to increase the pH of the pore water. Each of three columns was equipped with three miniature mesh wells to allow contact of the buffer with column pore water, but capsules (15 g) were inserted into only one column (amended). The two other columns served as amendment (no buffer) and abiotic (no denitrification) controls. Oxidation-reduction potential, dissolved organic and inorganic carbon, NH4+, NO3-+NO2-, PO43-, and pH were measured in the influent, two side ports, and effluent of the columns over time. Near complete conversion of 80 mg N/l of nitrate and 152 mg/l of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the amendment control column. The amended column maintained the target pH of 7.0+/-0.2 for 4 weeks until the capsules began to be depleted, after which time the pH slowly started to increase. The capsules exhibited pulses of buffer release, and were effectively dissolved after 7.5 weeks of operation. Base-neutralizing capacity contributed by the encapsulated buffer over the entire study period, calculated as cation equivalents, was 120 mM compared to 8 mM without buffer. This study demonstrates the potential for this technology to mediate pH changes and provides the framework for future studies in the laboratory and in the field, in which pH is controlled in order to enhance organic contaminant remediation by pH-sensitive systems. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • ISSN:
    0169-7722
  • Document Type:
    Text
  • Funding:
    Grant
  • Genre:
    Journal Article
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    81-98
  • Volume:
    54
  • Issue:
    1
  • NIOSHTIC Number:
    nn:20057763
  • Citation:
    J Contam Hydrol 2002 Jan; 54(1-2):81-98
  • Contact Point Address:
    C. Marjorie Aelion, Department of Environmental Health Sciences, University of South Carolina, Columbia, SC 29208, USA
  • Email:
    aelionm@sc.edu
  • Federal Fiscal Year:
    2002
  • Performing Organization:
    Arnold School of Public Health, University of South Carolina, Columbia
  • Peer Reviewed:
    True
  • Start Date:
    19940701
  • Source Full Name:
    Journal of Contaminant Hydrology
  • End Date:
    20040630
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:e9a3dde253b4785aa7137080524f37fb2c48ad553db8eba6a17372b7f65fd1563a0e8aa5400a12f05ca2f878348cd2a4ec13dfcf99c4b981c25e0b1181930ca2
  • Download URL:
  • File Type:
    Filetype[PDF - 248.15 KB ]
PREVIOUS
ON THIS PAGE
Details
CDC STACKS serves as an archival repository of CDC-published products including scientific findings, journal articles, guidelines, recommendations, or other public health information authored or co-authored by CDC or funded partners.

As a repository, CDC STACKS retains documents in their original published format to ensure public access to scientific information.
BACK TO TOP