Conventional wastewater treatments have high cost for human populations where the construction of sewage drainage is not possible. The vermifiltration is a low-cost, on-site and sustainable technology to solve this problem. The proposals of this study were to design and to install a pilot vermifiler (PV) and to evaluate the efficiency of removal of contaminants by vermifiltration. The PV was packed with organic filter media (vermicompost) and inorganic filter media (Tezontle). On the vermicompost were inoculated earthworms of the genus of Eisenia, sp. With the purpose to feed the worms with fresh solids wastes, it was placed a thin layer with sewage sludge and food wastes, (fruits and vegetables). The PV was fed with continuous flow of sanitary sewage water. The study was divided in three steps, with three rate of filtration and three surface organic loading rates. The influent and effluent were evaluated with conventional methods of water quality. Step 1, which was characterized by a rate of filtration 0.180 m3·m-2·d-1 and surface organic loading of 108 g·m-2·d-1, obtained greater removal of organic matter and suspended solids (92 % COD, 99 % BOD, 97 % TSS), also was efficient in the removal of ammonia (98 %) and in this step the PV obtained a greater removal of fecal coliforms (18.5 x 103 MPN·100 mL-1 to < 3 MPN·100 mL-1). The vermifilter was efficient in the removal of pollutants, and it obtained a significant removal of ammonia. In PV was obtained denitrification, but there was not a continuous process. It is necessary to follow the study to optimize the processes of denitrification, although the effluent can be reuse for agricultural or green areas irrigation. The two filter media proposed (vermicompost and Tezontle) were optimal to removal organic matter (COD and BOD), solids (SST) and ammonia.

Taking into account that important hydraulic structures are designed with hypothetical storms of 6 or 24 hours durations, in this research it was reviewed the time distribution of several rainfall events in the Coast of Chiapas in Mexico, especially those of duration of 24 and 6 hours and some of smaller duration. The reference pattern was that of the U. S. Service Conservation Soil (SCS) synthetic design storm type III for coastal areas. The data was obtained for year 2011, from April to November, and for October 2005, when occurred Stan Hurricane; the storms were distributed through 6 study sites instrumented with pluviographs. The Nash-Sutcliffe coefficient and the Relative error were the statistical parameters used as comparative criteria. In the case of 24-hours rainfall duration, their Nash-Sutcliffe coefficients presented values between 0.46; 0.89 and Relatives Error between 3.8 and 17 % and Standard Error between 9.26 and 17.37 %. In the case of the 6-hours rainfall duration only a 50 % of the events presented a good fit with Nash-Sutcliffe coefficients between 0.3 and 0.98; Relative Errors between 0.3 and 9.1 % and Standard Error between 3.71 and 16.40 % and when there was no good fit, the SCS intensity 6-hours duration values were below the real storm intensity values. Also it was found that the hyetographs for durations less than 6 hours presented a triangular distribution.

Trees planted for reforestation require of water for its survival and growth during the first three years after planting. Water in form of air water-vapor can be recovered to irrigate these plants. Silica gel a solid desiccant behaving like a sponge was used to adsorb air moisture and produce after heated. Three scale prototypes filled up with silica gel were developed comparing the water being recovered; one prototype was rolled by a stainless steel plate, another by cartoon and the last one by a stainless steel mesh. Tests were carried to determine the adsorption capacity, desorption caused by the heat, environmental exposition and adsorption speed. Dry silica gel adsorbed 38.8 % of its dry weight as water. Relative humidity sensor measurements nearby the silica gel did not indicated vapor water content adsorbed by the desiccant. Maximum 5.3 g·h-1 adsorption was obtained with the mesh prototype at an air speed of 2.6 m·s-1 requiring a big contact surface between the silica gel and the moist air. To produce 4 liters of water daily for irrigating a tree 13 kg of silica are required if the operating time is of 6 hours. The cylindrical prototype will be 83 cm long with a diameter of 30 cm.