Reduksi logam berat tembaga pada limbah tekstil

Iffah Khoiurn Nisak, Wignyanto, Nur Hidayat

Penelitian 2005

Abstrak

Tujuan penelitian ini adalah untuk mengetahui proporsi fortifikasi tepung limbah tapioka pada pellet dan waktu retensi yang tepat dalam usaha reduksi limbah logam berat tembaga pada limbah cair industri tekstil dengan metode bioremoval melalui penggunaan Rhizopus stolonifer.

Percobaan menggunakan rancangan tersarang dengan faktor utama adalah konsentrasi tepung limbah tapioka dan faktor tersarang waktu retensi.

Hasil penelitian menunjukkan bahwa kekeruhan mencapai nilai minimal sebesar 79 Ntu dengan konsentrasi tepung tapioka 100% dan waktu retensi 3 hari. pH optimal pada nilai 4,24 dengan konsentrasi tepung tapioka 50% dan waktu retensi 7 hari. Konsentrasi logam mencapai nilai 1,38 ppm pada konsentrasi tapioka 100% dengan waktu retensi 7 hari (reduksi 30,65%). Model yang terbentuk dari respon konsentrasi tembaga (Y) dengan konsentrasi tepung tapioka (A) dan waktu retensi (B) adalah:

Y = 1,68+0,004A^2+0,25B-0,016B^2

Effects of Growth Medium, Inoculum Size, and Incubation Time on Culturability and Isolation of Soil Bacteria

Applied and Environmental Microbiology, February 2005, p. 826-834, Vol. 71, No. 2

Kathryn E. R. Davis, Shayne J. Joseph, and Peter H. Janssen

Abstract

Soils are inhabited by many bacteria from phylogenetic groups that are poorly studied because representatives are rarely isolated in cultivation studies. Part of the reason for the failure to cultivate these bacteria is the low frequency with which bacterial cells in soil form visible colonies when inoculated onto standard microbiological media, resulting in low viable counts. We investigated the effects of three factors on viable counts, assessed as numbers of CFU on solid media, and on the phylogenetic groups to which the isolated colony-forming bacteria belong. These factors were inoculum size, growth medium, and incubation time. Decreasing the inoculum size resulted in significant increases in the viable count but did not appear to affect colony formation by members of rarely isolated groups. Some media that are traditionally used for soil microbiological studies returned low viable counts and did not result in the isolation of members of rarely isolated groups. Newly developed media, in contrast, resulted in high viable counts and in the isolation of many members of rarely isolated groups, regardless of the inoculum size. Increased incubation times of up to 3 months allowed the development of visible colonies of members of rarely isolated groups in conjunction with the use of appropriate media. Once isolated, pure cultures of members of rarely isolated groups took longer to form visible colonies than did members of commonly isolated groups. Using these new media and extended incubation times, we were able to isolate many members of the phyla Acidobacteria (subdivisions 1, 2, 3, and 4), Gemmatimonadetes, Chloroflexi, and Planctomycetes (including representatives of the previously uncultured WPS-1 lineage) as well as members of the subclasses Rubrobacteridae and Acidimicrobidae of the phylum Actinobacteria