Adam Sochacki

R&D priorities in the field of sustainable remediation and purification of agro-industrial and municipal wastewater

This article was presented as a position paper during the Environmental Biotechnology and Microbiology Conference in Bologna, Italy in April 2012. It indicates major and emerging environmental biotechnology research and development (R&D) priorities for EU members in the field of sustainable remediation and purification of agro-industrial and municipal wastewater. The identified priorities are: anaerobic/aerobic microbial treatment, combination of photochemical and biological treatment, phytoremediation and algae-based remediation, as well as innovative technologies currently investigated, such as enzyme-based treatment, bioelectrochemical treatment and recovery of nutrients and reuse of cleaned water. State of the art, research needs and prospective development in these domains are crucially discussed. As a result, goals of the future development of bioremediation and purification processes are defined and the way to achieve them is proposed.

Removal of diclofenac and sulfamethoxazole from synthetic municipal waste water in microcosm downflow constructed wetlands: Start-up results.

ABSTRACT The objectives of this study were to investigate the start-up removal of pharmaceutical compounds diclofenac and sulfamethoxazole in microcosm downflow constructed wetlands and their effect on the performance of the studied constructed wetlands, and also to assess the effect of plants on the removal of these compounds. The experimental system that was used in this 86-day experiment consisted of 24 columns filled up to 70 cm with predominantly sandy material. Four types of columns were used (six replicates) depending on the presence of plants (Phalaris arundinacea L. var. picta L.) and the presence of pharmaceutical compounds in the influent. The influent was synthetic municipal waste water to which a mixture of 5 mg/L of diclofenac and 5 mg/L of sulfamethoxazole was added. The observed removal of diclofenac was moderate (approx. 50%) and the removal of sulfamethoxazole was relatively low (24–30%). It was found that the removal of diclofenac and sulfamethoxazole was not affected by the vegetation. The presence of diclofenac and sulfamethoxazole in the influent had significant effect on the effluent concentration of N-NO3 and the water loss in the columns, which in both cases were lower than in the control columns. The scope for further research was discussed.

Degradation of benzotriazole and benzothiazole in treatment wetlands and by artificial sunlight

Laboratory-scale experiments were performed using unsaturated subsurface-flow treatment wetlands and artificial sunlight (with and without TiO2) to study the efficiency of benzotriazole and benzothiazole removal and possible integration of these treatment methods. Transformation products in the effluent from the treatment wetlands and the artificial sunlight reactor were identified by high performance liquid chromatography coupled with tandem mass spectrometry. The removal of benzothiazole in the vegetated treatment wetlands was 99.7%, whereas the removal of benzotriazole was 82.8%. The vegetation positively affected only the removal of benzothiazole. The major transformation products in the effluents from the treatment wetlands were methylated and hydroxylated derivatives of benzotriazole, and hydroxylated derivatives of benzothiazole. Hydroxylation was found to be the main process governing the transformation pathway for both compounds in the artificial sunlight experiment (with and without TiO2). Benzotriazole was not found to be susceptible to photodegradation in the absence of TiO2. The integration of the sunlight-induced processes (with TiO2) with subsurface-flow treatment wetlands caused further elimination of the compounds (42% for benzotriazole and 58% for benzothiazole). This was especially significant for the elimination of benzotriazole, because the removal of this compound was 96% in the coupled processes.

The treatment of wastewater containing pharmaceuticals in microcosm constructed wetlands: the occurrence of integrons (int1–2) and associated resistance genes (sul1–3, qacEΔ1)

The aim of this study was to analyze the occurrence of sulfonamide resistance genes (sul1–3) and other genetic elements as antiseptic resistance gene (qacEΔ1) and class 1 and class 2 integrons (int1–2) in the upper layer of substrate and in the effluent of microcosm constructed wetlands (CWs) treating artificial wastewater containing diclofenac and sulfamethoxazole (SMX), which is a sulfonamide antibiotic. The bacteria in the substrate and in the effluents were equipped with the sul1–2, int1, and qacEΔ1 resistance determinants, which were introduced into the CW system during inoculation with activated sludge and with the soil attached to the rhizosphere of potted seedlings of Phalaris arundinacea ‘Picta’ roots (int1). By comparing the occurrence of the resistance determinants in the upper substrate layer and the effluent, it can be stated that they neither were lost nor emerged along the flow path. The implications of the presence of antibiotic resistance genes in the effluent may entail a risk of antibiotic resistance being spread in the receiving environment. Additionally, transformation products of SMX were determined. According to the obtained results, four (potential) SMX transformation products were identified. Two major metabolites of SMX, 2,3,5-trihydroxy-SMX and 3,5-dihydroxy-SMX, indicated that SMX may be partly oxidized during the treatment. The remaining two SMX transformation products (hydroxy-glutathionyl-SMX and glutathionyl-SMX) are conjugates with glutathione, which suggests the ability of CW bacterial community to degrade SMX and resist antimicrobial stress.

Performance Intensifications in a Hybrid Constructed Wetland Mesocosm

This chapter presents the study on the performance of a hybrid mesocosm constructed wetland system composed of two treatment step: vertical flow bed and floating emergent macrophyte unit (a tank with a vegetated floating mat). The objectives of this study were to assess the performance intensifications in this system by assessing the effect of: (i) combing two types of constructed wetlands, (ii) increasing saturation level in the vertical flow unit, (iii) applying artificial intermittent aeration in the vertical flow unit, on the removal of carbonaceous compounds, nitrogen species and (phosphate phosphorus) P-PO4. The duration of the experiment was 378 days and it was divided into 4 periods: two periods with unsaturated vertical flow bed (but with different hydraulic loading rate values) and two periods with saturated bed of the vertical flow unit (in one period the bed was additionally intermittently aerated). The experimental system was fed with synthetic municipal waste water in a batch mode. It was observed that the intensification of the system’s performance by integrating a vertical flow bed with partly saturated conditions and a floating emergent macrophyte unit ensured high removal efficiencies for total nitrogen (TN) and P-PO4. Additionally, the application of artificial intermittent aeration in a vertical flow bed allowed achieving high removal efficiency of carbonaceous compounds (determined as dissolved organic carbon) without compromising the removal of TN and P-PO4. The scope of further research will include optimization of the system for hydraulic retention time and batch duration and monitoring of the fate of selected micropollutants in the system.

Polishing of Real Electroplating Wastewater in Microcosm Fill-and-Drain Constructed Wetlands

This chapter presents a study of the performance of metals removal mechanisms in microcosm fill-and-drain constructed wetlands used for polishing of real-life electroplating wastewater. Two types of columns were used in the experiment: with compost or sand bed media. All the columns were planted with common reed. The main design goal of the experimental system was to promote precipitation of metals with biogenic sulfides. The feed of the system contained mainly metals (Al, Cu, Ni, Zn), B, and cyanides. The substrate from the columns was sampled after cessation of the experiment (56 weeks) and was analyzed using a sequential extraction procedure and a scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS) method. The studied columns were found to remove Al, Cu, and cyanides to a high extent, but were less efficient for other metals and B. The obtained results showed that the intended process for metals removal, which was the precipitation of metal sulfides, was responsible for binding only a minor fraction of metals. The major portion of metals was present as exchangeable or reducible fraction.

Accumulation of Metals and Boron in Phragmites australis Planted in Constructed Wetlands Polishing Real Electroplating Wastewater

The concentration of metals (Al, Cu, Fe, Mn, Ni, Zn) and B were determined in the above- and belowground biomass of Phragmites australis collected from the microcosm constructed wetland system used for the polishing of real electroplating wastewater. Translocation factor and bioconcentration factor were determined. Pearson correlation test was used to determine correlation between metal concentration in substrate and above- and belowground parts of Phragmites australis. The obtained results suggested that Phragmites australis did not play a major role as an accumulator of metals. It was observed also that the substrate could have exerted an effect on the translocation of Ni, Cu, Zn and Mn. The analysed concentrations of metals and B in biomass were in the range or even below the concentrations reported in the literature with the exception of Ni. The aboveground biomass was found suitable as a composting input in terms of metals concentrations.

Removal and transformation of benzotriazole in manganese-oxide biofilters with Mn(II) feeding

The aim of this study was to evaluate the treatment of organic-carbon-deficient wastewater containing benzotriazole (BTA) in lab-scale aerated biofilters filled with natural manganese oxide ore, sand coated with synthetic manganese oxides and sand (as a control material) in terms of BTA removal efficiency, its transformation products and ecotoxicological impact of the treated wastewater. Additionally, the effect of Mn(II) feeding was tested. The removal of BTA in all the biofilters was ≥97%. The contribution of the biotic removal of this compound was 15%, 50%, and 75% in the systems filled with sand, synthetic and natural manganese oxides, respectively. Only the columns filled with natural manganese oxides provided significant removal of DOC and decrease of UV254 and SUVA254, with even more pronounced effect with Mn(II) feeding. The presence of Mn(II) was also found to enhance the removal of NNH4 in the systems filled with either form of manganese oxides, otherwise the removal of NNH4 was negligible or negative. The transformation reactions of BTA were methylation, hydroxylation, and triazole ring cleavage. Based on the number of compounds and their relative abundance, the methylated transformation products were predominant in the effluent. The reduction of the ecotoxicity (Microtox bioassay) of the effluents was positively correlated with the decrease of UV254, SUVA and DOC and only moderately with the removal of BTA. This study has shown that the natural manganese oxide ore provides the broadest set of services as a filtering material for aerated biofilters treating carbon-deficient wastewater containing BTA.