Treatment of landfill leachate by constructed wetlands

The performance of three constructed wetlands systems treating landfill leachate is described. Two are located in northern Poland (Szadolki near Gdansk and Gatka near Miastko) and one in southern Sweden (Örebro). The constructed wetlands in Szadolki consists of two parallel silty soil beds planted with reed with sub-surface horizontal flow of sewage. The constructed wetland in Gatka is a willow plantation on sandy soil, receiving leachate after preliminary sedimentation in a retention pond. The system in Örebro consists of a series of ponds with a surface flow of leachate, preceded by pre-treatment in an aerated tank with nitrogen stripping. The best treatment efficiencies were observed at Örebro. At the sub-surface flow wetlands in Szadolki and Gatka clogging problems occurred due to the unsatisfactory pre-treatment and low soil hydraulic conductivity resulting in lower treatment efficiencies

TREATMENT OF LANDFILL LEACHATE USING FILTER SUBSTRATES

SUMMARY: Three by-products from the steel and paper manufacturing industries have been tested as filter materials for removal of heavy metals in metal solution and in landfill leachate. Laboratory experiments were used to determine the capacity of the materials to remove heavy metals. A column set-up at a landfill site examined the field application possibilities of pine bark, amorphous and crystalline blast furnace slag. All three materials have shown large potential for removal of heavy metals in metal solution also when the concentrations are low. On-site treatment however was distrurbed by factors not present in batch experiments. Physical parameters such as pH and electric conductivity of the water stream were not significantly affected by the treatment

A CYTOGENETIC AND PHENOTYPIC CHARACTERIZATION OF SOMATIC HYBRID PLANTS OBTAINED AFTER FUSION OF 2 DIFFERENT DIHAPLOID CLONES OF POTATO (SOLANUM-TUBEROSUM L)

Somatic hybrid plants of various ploidy levels obtained after chemical fusion between two dihaploid clones of potato Solanum tuberosum L. have been analysed by cytological, morphological and molecular methods. The hybrid nature of tetraploid and hexaploid plants and the genome dosage in hexaploid hybrids were confirmed by Giemsa C-banding. Tetraploid and hexaploid hybrids showed numerical as well as structural chromosome mutations. The latter occurred mainly in the nuclear organizing chromosome. The tetraploid hybrids were more vigorous than the dihaploid parents as demonstrated by an increase in height, enlargement of leaves, increase in the number of internodes, restored potential for flowering and increased tuber yield. The grouping of tetraploid somatic hybrids into various classes on the basis of leaf morphology revealed that plants with a full chromosome complement were more uniform than aneuploids. Many hexaploid somatic hybrids were also more vigorous than the dihaploid parents and could be grouped into two different classes on the basis of floral colour and tuber characteristics, the differences being due to their different dosage of parental genomes. Most of the tetraploid somatic hybrids showed pollen development halted at the tetrad stage as one of the parental clones contained a S. stoloniferum cytoplasm. However, one tetraploid plant produced pollen grains with high viability. The chloroplast genome in the hybrid plants was determined by RFLP analysis. All of the hybrids had a cpDNA pattern identical to one parent, which contained either S. tuberosum or S. stoloniferum cpDNA. A slight preference for S. tuberosum plastids were observed in hybrid plants. No correlation between pollen development and plastid type could be detected