Sewage sludge

Les boues de station d'épuration sont constituées de sédiments résiduaires issus des traitements des eaux usées. En France, chaque habitant génère environ 50 g de matières sèches de boues par jour et ces résidus représentent environ 850 000 t de matières sèches par an. Actuellement, 60% des boues de station d'épuration produites en France sont épandues en agriculture alors que 20 à 25% sont mises en décharges et 15 à 20% sont incinérées. L'impact de la politique européenne en matière de traitement des eaux usées se traduit par une augmentation de la production des boues qui dépasserait, en France, un million de tonnes de matières sèches en 2005. Dans ce contexte général d'augmentation des quantités de boues, d'une part, et devant l'abandon progressif de la mise en décharge des déchets non ultimes, d’autre part, on voit difficilement comment la part de l'épandage pourrait diminuer. Cependant, la controverse qui s'est développée au cours des dernières a...

Increasing evidences have indicated that humic substances can induce plant growth and productivity by functioning as an environmental source of auxinic activity. Here we comparatively evaluate the effects of indole-3-acetic acid (IAA) and humic acids (HA) isolated from two different soils (Inseptsol and Ultisol) and two different organic residues (vermicompost and sewage sludge) on root development and on activities of plasmalemma and tonoplast H+ pumps from maize roots. The data show that HA isolated from these different sources as well as low IAA concentrations (10−10 and 10−15 M) improve root growth through a markedly proliferation of lateral roots along with a differential activation not only of the plasmalemma but also of vacuolar H+-ATPases and H+-pyrophosphatase. Further, the vacuolar H+-ATPase had a peak of stimulation in a range from 10−8 to 10−10 M IAA, whereas the H+-pyrophosphatase was sensitive to a much broader range of IAA concentrations from 10−3 to 10−15 M. It is proposed a complementary view of the acid growth mechanism in which a concerted activation of the plasmalemma and tonoplast H+ pumps plays a key role in the root cell expansion process driven by environment-derived molecules endowed with auxinic activity, such as that of humic substances.

Anaerobic digestion is an appropriate technique for the treatment of sludge before final disposal and it is employed worldwide as the oldest and most important process for sludge stabilization. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization, enhancement of dewatering of the

Sewage sludge not only our country all over the world have been among the major environmental problems. The right to correct the sludge to dry and / or burned or digested in anaerobic conditions to be considered as only temporary disposal methods. Sewage sludge drying and gasifiying with gasification technologies most appropriate way for eliminate is to apply the combined way. After the establishment of sewage sludge gasification method to eliminate the sludge and it is possible to obtain electrical and thermal energy. Part of the heat energy obtained from gas and it is possible to dry the sludge. Sewage sludge drying technology is described in detail earlier many studies. Therefore, this study tried to give general information gasification of sewage sludge after the first treatment method with gas production and with syngas by evaluating the energy production methods syngas gasification technologies will be tried to introduce. After drying and gasification of sewage sludge behind only ashes remain.

The present study focuses on the influence of the composting process on the formation of potentially bioavailable and sequestrated PAH fractions. The potentially bioavailable fraction was determined by means of a mild-solvent extraction (with n-butanol). The total and potentially bioavailable PAH content was evaluated in the consecutive composting stages, i.e. at the onset of the experiment, after the stabilization phase (on the 35th day), and after the maturation phase (on the 76th day). Four municipal sewage sludges with differentiated PAH content were selected for the present experiment. Eleven PAHs from the US EPA list (with exception of naphthalene, acenaphthylene, acenaphtene, fluorene and benz[ah]anthracene) were determined for the purpose of this experiment. The content of the total PAHs ranged from 3052 to 10 352 μg kg−1. The share of the potentially bioavailable fraction was at a similar level in the sludge samples tested and ranged from 75% to 81%. Greater differences were noted in the share of the bioavailable fraction in the case of individual PAH groups. The influence of the composting process on the contribution of the potentially bioavailable fraction of the PAH clearly depended on the stage of the experiment and sewage sludge type. However, in the case of all sludges, a lowering of the bioavailable fraction by 19–52% as compared to the level at the outset of the experiment was observed. During the first phase (stabilization) of the sewage sludge composting process, a reduction of the PAH content took place mainly at the expense of potentially bioavailable fraction, whereas in the second phase (maturation), sequestration processes predominated. The above phenomenon was most clearly visible for the 6-rings PAHs.

Composting is an alternative for recycling agricultural residues and sewage sludge, and the end pro- duct can be used as fertilizer for land application. In order to study the composting process with sludge from water sewage treatment plants and rice straw, environmental factors should be controlled. The aim of our study was to investigate the optimum C/N ratio, moisture and pH to maximize microbial activity. The incubation of sewage sludge and rice straw mixtures were conducted using an experiment design with three different C/N ratios (17, 24 and 41), moistures (40, 60 and 70 %) and pH (5.65, 6.65 and 8.75). The micro- bial activity was measured as manometric measurement of oxygen consumption. The enhancement of microbial activity is induced by low C/N ratio, high moisture content, and pH basic. Our results suggest that the initial blend with these raw materials must be about 17 C/N ratio, while moisture content must be between 60 % and the pH 8.75 in the composting process.

Surplus biological sludge from wastewater treatment plants was pyrolysed at 700 °C in the presence of H2SO4. Sludge-based (SB) activated carbon (AC) was mainly mesoporous in nature, with a surface area of 253 m2/g and an average pore diameter of 2.3 nm. Chemviron GW, an AC commercial reference, was mainly microporous with a surface area of 1026 m2/g and an average diameter of 1.8 nm. SB AC outperformed the commercial product in the removal of three anionic dyes in solution (CI Acid Brown 283, CI Direct Red 89 and CI Direct Black 168). Chemviron GW performed best for Basic Red 46, which may be related to the relatively small steric size of the dye molecules compared with the size of micropores, and to the greater surface area of the commercial AC. For equilibrium pH values between 5 and 9, the adsorption capacity of SB AC for dyes was significantly modified due to the presence of ionisable surface functional groups while that of Chemviron GW, with a more hydrophobic surface, remained unaltered.

... Research at FIU, and Dr. WJ Cooper, Director of DWRC at FIU. ... models, MS thesis, Department of Civil and Environmental Engineering, Florida International University, Miami, Florida. ... Tsihrintzis,VA, Fuentes, HR and Gadipudi, RK: 1996, Modeling prevention alternatives for ...

This study aimed at identifying the factors that affected the survival of faecal coliforms as measured by E. coli in four types of soils in Botswana which were amended with sewage sludge. Physico-chemical and biochemical properties and coliform population in the different soils, sludge, and soil/sludge mixtures were determined after sampling, on composing the soil/sludge mixtures, and 90 days after composing. Coliform

Incubation tests were used to assess the effectiveness of three different organic residues and three different liming materials, alone or in combination, in the remediation of a mine contaminated soil. The organic residues tested were sewage sludge from a municipal wastewater ...