Elizabeth Duarte

Evaluation of composts and liming materials in the phytostabilization of a mine soil using perennial ryegrass

A microcosm experiment was carried out to evaluate the effects of municipal solid waste compost (MSWC) or garden waste compost (GWC), and liming materials in the rehabilitation of a soil affected by mining activities, and to study the use of perennial ryegrass (Lolium perenne L.) for phystostabilization. The performance of the amendments was assessed by soil chemical parameters, total and bioavailable metals (Cu, Pb and Zn), soil enzymatic activities, and plant relative growth and mineral composition. In general, both composts corrected soil acidity and increased the total organic matter content of the soil, although with a better performance in the case of MSWC, especially when considering total N and available P and K levels in the amended soil. The application of both composts and liming materials led to a decrease in the mobile fractions of Cu, Pb and Zn, but mobilisable fractions of Cu and Zn increased with MSWC application. Plant biomass increased more than three times in the presence of 50 Mg MSWC ha(-1) and with the combined use of 25 or 50 Mg MSWC ha(-1) and CaO, but no significant differences were observed when GWC was applied. Plant tissue analysis showed that the treatments did not significantly reduce Cu, Pb and Zn uptake by the plant. Dehydrogenase, and the enzymes related to the N-cycle, urease and protease, had increased activities with increasing MSWC application rate. Conversely, the enzymatic activities of both enzymes related to the C-cycle, cellulase and beta-glucosidase, were only positively affected by GWC application, a compost obtained from raw materials rich in C. Principal component analyses evidenced this clear separation between the effect of MSWC on soil enzymes related to the N-cycle and of GWC on soil enzymes related to the C-cycle. This study indicates that MSWC (50 Mg ha(-1), limed or unlimed) can be used successfully in the remediation of a highly acidic metal-contaminated soil, allowing the establishment of perennial ryegrass.

Assessment of chemical, biochemical and ecotoxicological aspects in a mine soil amended with sludge of either urban or industrial origin

A greenhouse pot experiment was conducted to evaluate the effect of sewage sludge (SS), of sugar beet sludge (SBS), or of a combination of both, in the remediation of a highly acidic (pH 3.6) metal-contaminated soil, affected by mining activities. The SS was applied at 100 and 200 Mg ha(-1) (dry weight basis), and the SBS at 7 Mg ha(-1). All pots were sown with Italian ryegrass (Lolium multiflorum Lam.). After 60 d of growth, shoot biomass was quantified and analysed for Cu, Pb and Zn. The pseudo-total and bioavailable contents of Cu, Pb and Zn and the enzymatic activities of beta-glucosidase, acid phosphatase, cellulase, protease and urease were determined in the soil mixtures. Two indirect acute bioassays with leachates from the soil (luminescent inhibition of Vibrio fischeri and Daphnia magna immobilization) were also used. The SS, in particular when in combination with SBS, corrected soil acidity, while increasing the total organic matter content and the cation exchange capacity. The application of SS led to a decrease in the level of effective bioavailable metals (extracted by 0.01 M CaCl(2), pH 5.7, without buffer), but caused an increase in their potential bioavailability (extracted by a solution of 0.5M NH(4)CH(3)COO, 0.5 M CH(3)COOH and 0.01 M EDTA, pH 4.7). Plant biomass increased more than 10 times in the presence of 100 Mg SS ha(-1), and more than five times with the combined use of 100 Mg SS ha(-1) and SBS, but a considerable phytotoxic effect was observed for the application rate of 200 Mg SS ha(-1). Copper, Pb and Zn concentrations in the shoots of L. multiflorum decreased significantly when using 100 Mg SS ha(-1) or SBS. The activities of beta-glucosidase, urease and protease increased with increasing SS applications rates, but cellulase had a reduced activity when using 200 Mg ha(-1)SS. Both amendments were able to suppress soil toxicity to levels that did not affect D. magna, but increased the soil leachate toxicity towards V. fischeri, especially with the application of 200 Mg SS ha(-1). This study showed that for this type of mine soils, and when using SS of similar composition, the maximum SS application rate should be 100 Mg ha(-1), and that liming the SS amended soil with SBS did not contribute to a further improvement in soil quality.

Reclamation of a mine contaminated soil using biologically reactive organic matrices.

Organic residues such as sewage sludge, biowastes and composts are increasingly used in land rehabilitation because they can improve the physical, chemical and biochemical properties of soil, and reduce the need for inorganic fertilization. Furthermore, their use contributes to an integrated approach to waste management by promoting recycling of nutrients and minimizing final disposal, especially of organic residues that, due to their composition, can pose problems to agricultural soils. In the present study, three different types of organic residues were considered as amendments to be used in the reclamation of a metal-contaminated mine soil from the Aljustrel mining area (a pyrite mine located in the SW Portugal in the Iberian Pyrite Belt), with high Cu, Pb and Zn total contents: sewage sludge from a municipal wastewater treatment plant (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC), applied at 100 and 200 Mg ha—1 . The soil and mixtures of soil and amendments were adjusted to 70% of the maximum water-holding capacity determined for each type of sample and incubated in a controlled-temperature room at 20 ± 1 °C. Sub-samples were taken prior to wetting (time zero), and after 7, 14, 21 and 28 days of incubation, and analysed for pH, electrical conductivity, organic matter content, effectively bioavailable Cu, Zn and Pb (extracted with 0.01 mol L— 1 calcium chloride) and potentially bioavailable metals (extracted with 0.5 mol L—1 ammonium acetate, 0.5 mol L —1 acetic acid and 0.01 mol L— 1 EDTA, pH 4.7). In general, organic residues corrected soil acidity, and increased the total organic matter content of the soil. The SS and the MSWC amendments were roughly equivalent in their ability to correct soil acidity whereas the GWC had the smallest liming capacity and only with 200 Mg ha—1 GWC did the soil pH reach acceptable values. As expected, all the tested organic residues, at both application rates, were effective in reducing the effectively bioavailable metals in the soil. The Zn bioavailability was the most affected by the addition of organic residues, whereas Pb bioavailability was small even in the unamended soil and was the least affected by treatments. Potentially bioavailable metals increased with SS and MSWC application and the opposite was true following amendment with GWC.

Integrated approach to winery waste: waste generation and data consolidation

The winemaking process involves the generation of a significant amount of waste and wastewater. These residues should be addressed for recycling or treatment before being returned to environment. As each winery is unique in waste generation and disposal, plans for environmentally friendly waste management are not universal and should be tested for their effectiveness. In this study, a diagnostic was made during three years, in different wineries, throughout Portugal, in order to quantify and characterize the waste and the wastewater produced. The results showed that solid waste and wastewater are mainly produced during the harvest period, corresponding to 74% and 87%, respectively. One ton of processed grape approximately produce 0.13 t marc, 0.06 t lees, 0.03 t of stalks and 1.65 m3 of wastewater. No significant differences (P⩽0.05) were observed for grape marc, lees and wastewater ratios, between years or wineries. With respect to the stalk ratio, there was no effect of year but the winery significantly affected this ratio (P⩽0.05). During the study period the treated wastewater, since diluted, revealed suitable characteristics for irrigation representing an additional source of water. In this regard, the data acquisition and consolidation ensure the transfer of information and experience which constitute an essential step in a support decision tool design.

Utilization of wasted sardine oil as co-substrate with pig slurry for biogas production - a pilot experience of decentralized industrial organic waste management in a Portuguese pig farm.

This work aimed to demonstrate in a pig farm and in real conditions, the possibilities to co-digest wasted sardine oil (WSO) and pig slurry (PS) at farm scale. A biogas mobile pilot plant, was set up in the farm and operated in real conditions during 4 months. Dynamic mesophilic (35-37 °C) continuous pilot trials were performed during four different periods of time. In each period a different organic loading rate (OLR) based on the chemical oxygen demand (COD) was operated sequentially, with pig slurry (PS) (OLR = 1.6 kg COD/m(3) d(-1)) and with mixtures of WSO:PS with a volumetric composition (% v/v) of 2:98 (OLR = 3.0 kg COD/m(3) d(-1)), 3:97 (OLR = 3.7 kg COD/m(3) d(-1)) and 5:95 (OLR = 5.2 kg COD/m(3) d(-1)). Biomass adapted very fast in metabolise the WSO and biogas productivity was raised substantially for different compositions of WSO:PS. Process stability indicators pH and Total volatile fatty acids/bicarbonate alkalinity (T-VFA/BA) ratio, suggests that the co-digestion process was robust. It was concluded that WSO could be easily co-digested in farm scale biogas plants.

Aerobic treatment of winery wastewater with the aim of water reuse

An air micro-bubble bioreactor (AMBB) using a free self-adapted microbial population, 15 dm3 working volume, was used for aerobic treatment of winery wastewater. This reactor utilizes a Venturi injector in conjunction with mass transfer multiplier nozzles, which allow an efficient oxygen transfer. The reactor can operate in batch or continuous conditions. The dynamics of chemical oxygen demand (COD), biomass and total contents of polyphenolic compounds was followed throughout each trial. The wastewater COD ranged between 4.0-8.0 kg COD m(-3) and the efficiency of the batch treatment was about 90.0 +/- 4.3%, after 6 days of operation. The maximum efficiency obtained was achieved after 15 days of treatment (99%). In continuous conditions, the loading rate and the treatment efficiency ranged between 0.45-1.00 kg COD m(-3) d(-1) and 93.3 +/- 2.0%, respectively. The AMBB hydraulic retention time was 15 days. To assess the suitability of treated water in relation to vineyard irrigation, the effluent was physico-chemical analysed and direct toxicity bioassays with effluent matrix were carried out using Lepidium sativum L. seeds. The results showed the water quality required to be reutilised minimizing water consumption. This study will contribute for the implementation of an efficient water use plan, aiming the preservation of the water resource and the reduction of the wastewater production.

Overview of the state of the art of constructed wetlands for decentralized wastewater management in Brazil

Conventional wastewater treatment plants (WWTPs) commonly require large capital investments as well as operation and maintenance costs. Constructed wetlands (CWs) appear as a cost-effective treatment, since they can remove a broad range of contaminants by a combination of physical, chemical and biological processes with a low cost. Therefore, CWs can be successfully applied for decentralized wastewater treatment in regions with low population density and/or with large land availability as Brazil. The present work provides a review of thirty nine studies developed on CWs implemented in Brazil to remove wastewater contaminants. Brazil current sanitation data is also considered to evaluate the potential role of CWs as decentralized wastewater treatment. Performance of CWs was evaluated according to (i) type of wetland system, (ii) different support matrix (iii) vegetation species and (iv) removal efficiency of chemical oxygen demand (COD), biological oxygen demand (BOD5), nitrogen (N), and phosphorus (P). The reviewed CWs in overall presented good efficiencies, whereas H-CWs achieved the highest removals for P, while the higher results for N were attained on VF-CW and for COD and BOD5 on HF-CW. Therefore, was concluded that CWs are an interesting solution for decentralized wastewater treatment in Brazil since it has warm temperatures, extensive radiation hours and available land. Additionally, the low percentage of population with access to the sewage network in the North and Northeast regions makes these systems especially suitable. Hence, the further implementation of CW is encouraged by the authors in regions with similar characteristics as Brazil.

Occurrence and analysis of endocrine-disrupting compounds in a water supply system

This paper presents the study of the occurrence of 10 endocrine-disrupting compounds (EDCs) in 60 water samples using a method for simultaneous quantification and confirmation of the presence of these emerging compounds, using ultra-performance liquid chromatography with electrospray ionization and tandem mass spectrometry (UPLC-ESI-MS/MS). All samples were previously extracted by solid-phase extraction (SPE). Several natural and synthetic hormones (17-β-estradiol, ethinylestradiol, estriol, estrone, progesterone, mestranol, and diethylstilbestrol) and some industrial products (4-n-nonylphenol, 4-tert-octylphenol, and bisphenol A) were chosen for this survey. The analytical limits were calculated for each compound and were used in the identification and quantification of these target compounds in EPAL’s water supply system. In this study, several samples were taken from the main intakes of water (surface and groundwater) used for production of water for human consumption and from different sampling points of the drinking water distribution system (piping, nets, and reservoirs). Some target compounds, such as estriol, 4-tert-octylphenol, mestranol, and nonylphenol, were found in trace amounts in several water samples. However, the studied endocrine-disrupting appeared in very low concentrations when compared with the assessed analytical limits.

Reuse of drinking water treatment sludge for olive oil mill wastewater treatment

Olive mill wastewater (OMW) results from the production of olive oil, which is an important traditional agro-industry in Mediterranean countries. In continuous three-phase centrifugation 1.0-1.2 m(3) of OMW are produced per ton of processed olives. Discharge of OMW is of serious environmental concern due to its high content of organic matter with phytotoxic properties, namely phenolic compounds. Meanwhile, drinking water treatment sludge (DWTS) is produced in high amounts and has long been considered as a waste for landfill. The aim of this work was the assessment of reusing DWTS for OMW treatment. High performance liquid chromatography (HPLC) analysis was carried out to determine the phenolic compounds present and to evaluate if they are recalcitrant. Treatability assays were performed using a dosage of DWTS from 50 to 300 g L(-1). Treatment efficiency was evaluated based on the removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solids (TS), total suspended solids (TSS), total volatile solids (TVS), oil and grease (OG), phenols (total phosphorous (TP) and HPLC fraction). Results from OMW HPLC characterization identified a total of 13 compounds; the major ones were hydroxytyrosol, tyrosol, caffeic acid, p-cumaric acid and oleuropein. Treatability assays led to a maximum reduction of about 90% of some of the phenolic compounds determined by HPLC. Addition of 200-300 g L(-1) of DWTS reduced 40-50% of COD, 45-50% of TP, a maximum of nearly 70% TSS and 45% for TS and TVS. The OG fraction showed a reduction of about 90%, achieved adding 300 g L(-1) od DWTS. This study points out the possibility of establishing an integrated management of OMW and DWTS, contributing to a decrease in the environmental impact of two industrial activities, olive oil production and drinking water treatment.

Influence of nitrogen content in the soil solution on potential nitrogen mineralization of organic residues

Application of organic residues to soil may supply nutrients to plant, namely, nitrogen (N). But, generally, organic residues contain mostly organic N that has to be mineralized prior to plant uptake. This process depends on several parameters such as the carbon to nitrogen ratio of the residues or the soil moisture. The aim of the present work was to assess the effect of the ammonium (NH4 +) and organic N contents of the soil solution on potential N mineralization (PNM) of organic residues applied to soil. Seven organic residues (rice straw, wheat straw, maize straw, sewage sludge, liquid pig manure, poultry manure, and poultry excreta) combined each with three soil solutions: Norg+min (63 mg L−1 total N with 47% organic N and 53% NH4 +-N), Norg (5.6 mg L−1 total N with 92% organic N and 8% NH4 +-N), and control (no N) were compared. Our results indicated that a small amount of organic N and low NH4 +-N in the soil solution enhanced the PNM of organic residues, whereas larger amounts of NH4 +-N and organic N in the same proportions decreased the PNM and could lead to N immobilization.