Britt-Marie Svensson

Combined anaerobic–ozonation process for treatment of textile wastewater: Removal of acute toxicity and mutagenicity

A novel set up composed of an anaerobic biofilm reactor followed by ozonation was used for treatment of artificial and real textile effluents containing azo dyes. The biological treatment efficiently removed chemical oxygen demand and color. Ozonation further reduced the organic content of the effluents and was very important for the degradation of aromatic compounds, as shown by the reduction of UV absorbance. The acute toxicity toward Vibrio fischeri and the shrimp Artemia salina increased after the biological treatment. No toxicity was detected after ozonation with the exception of the synthetic effluent containing the highest concentration, 1 g/l, of the azo dye Remazol Red. Both untreated and biologically treated textile effluents were found to have mutagenic effects. The mutagenicity increased even further after 1 min of ozonation. No mutagenicity was however detected in the effluents subjected to longer exposure to ozone. The results of this study suggest that the use of ozonation as short post-treatment after a biological process can be beneficial for the degradation of recalcitrant compounds and the removal of toxicity of textile wastewater. However, monitoring of toxicity and especially mutagenicity is crucial and should always be used to assess the success of a treatment strategy.

Leachability testing of metallic wastes.

The performance of two tests, a batch test and a percolation test for the characterization of waste as suggested in the EU council decision 2003/33/EC was investigated. The tests were carried out on two solid waste streams from a metal recycling industry. The concentrations of heavy metals such as Cu, Znand Pb were more than one order of magnitude lower than the proposed limit values. Generally, batch test values were equal or higher than percolation test values. With the proposed test procedures both materials could be considered as non-dangerous wastes. The test performance was also investigated using a leachant with higher ionic strength instead of demineralized water as prescribed. The results clearly show a significant increase in the concentration of some heavy metals. Total concentrations of phenolic compounds and polychlorinated biphenyls were less than 1 p.p.m. and 2 p.p.b., respectively. The precision of the batch and the percolation tests were on average 48 and 35%, respectively.

Development and application of an analytical protocol for evaluation of treatment processes for landfill leachates. II. Evaluation of leachate treatment efficiency of different steps in a constructed pilot plant

Different methods for treatment of leachate from a municipal solid waste (MSW) landfill were tested in a pilot plant. Raw leachate was pre-treated with aeration and sedimentation, followed by several parallel individual steps such as bioremediation, chemical oxidation, ozonation, and geo-bed filters. The efficiency of different treatment steps was evaluated according to one previously developed protocol, which includes measurements of several parameters such as conductivity, pH, nutrients, chloride, metals, organic compounds, and acute toxicity before and after a treatment step. The treatment steps which showed the highest efficiency towards organic pollutants in leachate were ozone treatment and chemical oxidation. The use of an adsorption filter, a geo-bed with a mixture of peat and bottom ash with ca 10% remaining carbon, also had good effects. A combination of pre-treatment and a geo-bed filter with peat and carbon ash gave the best overall treatment results when water-quality parameters such as total organic carbon and ammonia-nitrogen were also considered.

Development and application of an analytical protocol for evaluation of treatment processes for landfill leachates : I. Development of an analytical protocol for handling organic compounds in complex leachate samples

A strategy is presented for evaluation of treatment procedures for landfill leachate with emphasis on organic pollutants. An analytical scheme, the LAQUA protocol, was developed as a guide for the analytical work. The protocol includes organic as well as metals, inorganic ions, water-quality parameters, and toxicity. The proposed strategy considers the behaviour of both polar and non-polar organic substances at trace levels. For polar substances, phenols were chosen as markers and determined with an automated supported liquid membrane extraction device, coupled on-line to HPLC with a diode-array detector. For non-polar substances, PCBs and 10 unidentified compounds were chosen as markers and analysed by solid-phase extraction combined with supercritical fluid extraction with GC analysis. The chosen measurement strategy, based on the use of marker substances, difference measurements, and versatile data-handling procedures, provided essential information about complex systems at relatively low cost.

Column studies aiming at identification of suitable filter materials for pollutant removal from landfill leachate

Landfill leachate contains a complex mixture of inorganic and organic pollutants, which need to be removed before they pollute the environment. Different filter media (peat mixed with either carbon-containing ash, polyurethane waste, or wood pellets) were investigated with respect to their possibility to simultaneously and at low initial concentrations remove metals, polar and non-polar organic compounds. The mixture of peat and carbon-containing ash was found to be the best medium. Reduction in leachate of phenolic substances was 96%, of PBDEs was over 98%, of DOC 40% and of important metals as Cu, Pb and Sn 60%, 90% and 93%, respectively.

Treatment of wood leachate with high polyphenols content by peat and carbon-containing fly ash filters

In the present study, two combinations of filter materials in filter/columns were examined for removal of total organic carbon (TOC) and polyphenols (PP) found in storm water runoff from wood storage areas in a wooden floor industry. One filter/column was packed with peat mixed with carbon-containing fly ash, while another filter/column contained only peat (without ash). The mixture of peat and ash has shown faster and higher removal capacity for TOC and faster removal with the same final removal capacity for PP (in grams of pollutant per kg of sorbent) at the saturation point. The superiority observed for the peat and ash filter is presumably due to the unique characteristics of peat and ash, which enhanced the treatment efficiency when used together in a mixture. Based on the observed results, filters formed by peat and carbon-containing ashes proved to be a potentially low-cost option for the treatment of storm water generated at storage areas of wood materials such as logs, sawdust and wood chips.

Leachability testing of sludge from street gullies

Sludge from gullies, on two types of streets with different traffic intensity, was investigated using two recommended EU methods for leachability testing of waste: a two-stage batch test and an up-flow percolation test. The main purpose of this investigation was to gain more knowledge about these leaching test methods to be able to make future decisions on the general applicability of the proposed tests. A number of parameters were determined in the sludge as well as in the eluates obtained from the two leaching tests. These include pH, conductivity, dissolved organic carbon and inorganic ions as chloride ions. A number of metals as Cd, Cr, Cu, Hg, Ni and Zn, were determined by inductive coupled plasma-mass spectrometry and organic compounds were screened by high performance liquid chromatography-diode array UV detection and gas chromatography-mass spectrometry. It was found that the concentrations of metals and organic compounds in the sludge were several orders of magnitudes higher than the actual eluate concentrations. For all metals the concentrations were well below the proposed limit values for non-hazardous waste included in the Council decision document 2003/33/EC. Generally, concentrations obtained in batch test were equal or higher than from percolation tests. The repeatability of the percolation and the batch test were in average 28 and 17%, respectively.