(Appendix A) Sedimentation rate, geochemical and environmental magnetic proxies of the samples of the Metochia section, on the island of Gavdos, south of Crete

The upper Tortonian Metochia marls on the island of Gavdos provide an ideal geological archive to trace variations in Aegean sediment supply as well as changes in the North African monsoon system. A fuzzy-cluster analysis on the multiproxy geochemical and rock magnetic dataset of the astronomically tuned sedimentary succession shows a dramatic shift in the dominance of 'Aegean tectonic' clusters to 'North African climate' clusters. The tectonic signature, traced by the starvation of the Cretan sediment, now enables to date the late Tortonian basin foundering on Crete, related to the tectonic break-up of the Aegean landmass, at c. 8.2 Ma. The synchronous decrease in the North African climate proxies is interpreted to indicate a change in the depositional conditions of the sink rather than a climatic change in the African source. This illustrates that interpretations of climate proxies require a multiproxy approach which also assesses possible contributions of regional tectonism.

Dinâmica de Sedimentação de Lodo em Lagoas de Estabilização

Stabilization ponds are an effective sewage treatment alternative for the climatic conditions prevailing in Brazil. In the present work, a primary facultative pond was studied, in the city of Natal, Rio Grande do Norte, Northeast Brazil. The aim of this study was to evaluate the sedimentation dynamics in the facultative pond. The pond was divided in three section or zones along its length starting from the inlet end namely A1, A2 and A3. The research was accomplished in three phases. In the first the mapping of the sludge layer was done, sludge core samples were also collected for analysis for total, fixed and volatile solids and the depth of the sludge layer was determined using a portable echo sounder. In the second solids sedimentation rates were measured using traps placed in the inlet and outlet zones and in the third phase resuspension sludge was evaluate using a tracer. The amount accumulated sludge since the start operation was 13.583 m3. The sedimentation constant averages changed between 0.93 to 2.94 and 3.90 to 5.80 for the depths of 0.5 and 1.0 m respectively. The relationship between volatile and fixed solids (SV/SF) increased along the pond. The removal efficiencies were 52.12%, 36.09%, and 37.50% for BOD, COD and SS, respectively. The sludge accumulation model proposed had a good adjustment with 0.17 m3/hab.year rate. The results presented here demonstrated that the wind had a direct influence on the sedimentation of solids in this pond affecting the efficiency and sludge accumulation

Avaliação de processo de lodos ativos por batelada seguido de tratamento terciário com ênfase na remoção de matéria orgânica e na sedimentabilidade do lodo

This paper evaluate the performance of a Wastewater Treatment Plant (WWTP) in sequential batch activated sludge modality with tertiary treatment step, located in high temperature region. It also presents the analysis of organic matter’s removal and the evaluation of sludge sedimentation conditions through reactors in bench scale, fed with different substrate’s and biomass’ concentrations, from the WWTP in study. The results showed high efficiency and stability of the treatment process using Sequential Batch Reactors for domestic sewage, even with sudden changes of organic and hydraulic load, reaching more than 90% of efficiency in the removal of biodegradable organic matter. The removal of organic matter and sedimentation tests in bench reactors showed the good performance in respect of the organic matter’s removal, however, the high concentration of micro-organism results in a lower sludge sedimentation rate, which can compromise the quality of the final effluent. The relation Food/Microorganism in the conditions of the WWTP’s current operation showed a value of 0.06 gCOD/gVSS.d. and zonal sedimentation velocity of 0.59 m/h, the great ratio of the concentration of the substrate by biomass concentration, which obtained the maximum operational efficiency, showed a value of 0.09 gCOD/gVSS.d. and zonal sedimentation velocity of 1.4 m/h.

Avaliação de processo de lodos ativos por batelada seguido de tratamento terciário com ênfase na remoção de matéria orgânica e na sedimentabilidade do lodo

This paper evaluate the performance of a Wastewater Treatment Plant (WWTP) in sequential batch activated sludge modality with tertiary treatment step, located in high temperature region. It also presents the analysis of organic matter’s removal and the evaluation of sludge sedimentation conditions through reactors in bench scale, fed with different substrate’s and biomass’ concentrations, from the WWTP in study. The results showed high efficiency and stability of the treatment process using Sequential Batch Reactors for domestic sewage, even with sudden changes of organic and hydraulic load, reaching more than 90% of efficiency in the removal of biodegradable organic matter. The removal of organic matter and sedimentation tests in bench reactors showed the good performance in respect of the organic matter’s removal, however, the high concentration of micro-organism results in a lower sludge sedimentation rate, which can compromise the quality of the final effluent. The relation Food/Microorganism in the conditions of the WWTP’s current operation showed a value of 0.06 gCOD/gVSS.d. and zonal sedimentation velocity of 0.59 m/h, the great ratio of the concentration of the substrate by biomass concentration, which obtained the maximum operational efficiency, showed a value of 0.09 gCOD/gVSS.d. and zonal sedimentation velocity of 1.4 m/h.

Radiocarbon age, and sedimentation and accumulation rate of core JM05-G001 obtained during Jan Mayen cruise JM050704 to the Barents Sea

Instrumental monitoring of the climate at high northern latitudes has documented the ongoing warming of the last few decades. Climate modelling has also demonstrated that the global warming signal will be amplified in the polar region. Such temperature increases would have important implications on the ecosystem and biota of the Barents Sea. This study therefore aims to reconstruct the climatic changes of the Barents Sea based on benthic foraminifera over approximately the last 1400 years at the decadal to sub-decadal scale. Oxygen and carbon isotope analysis and benthic foraminiferal species counts indicate an overall warming trend of approximately 2.6°C through the 1400-year record. In addition, the well-documented cooling period equating to the 'Little Ice Age' is evident between c. 1650 and 1850. Most notably, a series of highly fluctuating temperatures are observed over the last century. An increase of 1.5°C is shown across this period. Thus for the first time we are able to demonstrate that the recent Arctic warming is also reflected in the oceanic micro-fauna.

Sewage Sludge Electro-Dewatering

Original sludge from wastewater treatment plants (WWTPs) usually has a poor dewaterability. Conventionally, mechanical dewatering methods are used to increase the dry solids (DS) content of the sludge. However, sludge dewatering is an important economic factor in the operation of WWTPs, high water content in the final sludge cake is commonly related to an increase in transport and disposal costs. Electro‐dewatering could be a potential technique to reduce the water content of the final sludge cake, but the parameters affecting the performance of electro‐dewatering and the quality of the resulting sludge cake, as well as removed water, are not sufficiently well known. In this research, non‐pressure and pressure‐driven experiments were set up to investigate the effect of various parameters and experimental strategies on electro‐dewatering. Migration behaviour of organic compounds and metals was also studied. Application of electrical field significantly improved the dewatering performance in comparison to experiments without electric field. Electro‐dewatering increased the DS content of the sludge from 15% to 40 % in non‐pressure applications and from 8% to 41% in pressure‐driven applications. DS contents were significantly higher than typically obtained with mechanical dewatering techniques in wastewater treatment plant. The better performance of the pressure‐driven dewatering was associated to a higher current density at the beginning and higher electric field strength later on in the experiments. The applied voltage was one of the major parameters affecting dewatering time, water removal rate and DS content of the sludge cake. By decreasing the sludge loading rate, higher electrical field strength was established between the electrodes, which has a positive effect on an increase in DS content of the final sludge cake. However interrupted voltage application had anegative impact on dewatering in this study, probably because the off‐times were too long. Other factors affecting dewatering performance were associated to the original sludge characteristics and sludge conditioning. Anaerobic digestion of the sludge with high pH buffering capacity, polymer addition and freeze/thaw conditioning had a positive impact on dewatering. The impact of pH on electro‐dewatering was related to the surface charge of the particles measured as zeta‐potential. One of the differences between electro‐dewatering and mechanical dewatering technologies is that electro‐dewatering actively removes ionic compounds from the sludge. In this study, dissolution and migration of organic compounds (such as shortchain fatty acids), macro metals (Na, K, Ca, Mg, Fe) and trace metals (Ni, Mn, Zn, Cr) was investigated. The migration of the metals depended on the fractionation and electrical field strength. These compounds may have both negative and positive impacts on the reuse and recycling of the sludge and removed water. Based on the experimental results of this study, electro‐dewatering process can be optimized in terms of dewatering time, desired DS content, power consumption and chemical usage.

Influence of time on the plant availability of Cd, Ni and Zn after sewage sludge has been applied to soils

A pot experiment was conducted to test the hypothesis that decomposition of organic matter in sewage sludge and the consequent formation of dissolved organic compounds (DOC) would lead to an increase in the bioavailability of the heavy metals. Two Brown Earth soils, one with clayey loam texture (CL) and the other a loamy sand (LS) were mixed with sewage sludge at rates equivalent to 0, 10 and 50 1 dry sludge ha(-1) and the pots were sown with ryegrass (Lolium perenne L.). The organic matter content and heavy metal availability assessed with soil extractions with 0.05 M CaCl2 were monitored over a residual time of two years, while plant uptake over one year, after addition of the sludge. It was found that the concentrations of Cd and Ni in both the ryegrass and the soil extracts increased slightly but significantly during the first year. In most cases, this increase was most evident especially at the higher sludge application rate (50 t ha(-1)). However, in the second year metal availability reached a plateau. Zinc concentrations in the ryegrass did not show an increase but the CaCl2 extracts increased during the first year. In contrast, organic matter content decreased rapidly in the first months of the first year and much more slowly in the second (total decrease of 16%). The concentrations of DOC increased significantly in the more organic rich CL soil in the course of two years. The pattern followed by the decomposition of organic matter with time and the production of DOC may provide at least a partial explanation for trend towards increased metal availability.