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A diagnosis, carried out as part of the conception of the National Sanitation Strategy of the Dominican Republic, states that 75% of the population does not have sewerage services, and just around 10% of the wastewater generated receive some treatment. Furthermore, the discharge of sewage from more than a million septic tanks in the country constitutes the largest source of diffuse pollution. Regarding the above mentioned, "Plan Yaque" (Plan for the Sustainable Development of the Yaque del Norte River Basin) has implemented a relatively cost-effective solution in "El Dorado," a small peri-urban settlement in Jarabacoa municipality. Nonpoint source pollution was converted into point source through a system that collects all the sewage from each septic tank and, then, brings those wastewaters into a nature-based treatment system (constructed wetland with the subsurface flow). This work shows the results obtained in the assessment of the design and exploitation of a wastewater treatment system targeting to reduce the pollution's load that is affecting the Yaque del Norte River Basin. The treatment system is based on a sewer system that brings the sewage from the houses into two septic tanks, from where they are brought to a constructed wetland. The 70 m2 wetland was designed to treat the sewage generated by 75 inhabitants. Because of the treatment, the decrease of the pollutant's load into the inflowing sewage achieved an average removal value of 93% for COD, 95% for BOD, 98% for fecal coliforms and 44% for phosphorus as orthophosphate. The system could potentially spread out in other peri-urban settlements in developing countries. [ABSTRACT FROM AUTHOR]

Feasibility of using up-flow anaerobic sludge blanket (UASB) reactor for the treatment of sewage water was studied. Three similar UASB reactors were operated at three different hydraulic retention time (HRT) of 6, 8 and 10 hrs. The reactors were operated with activated sludge inoculation in June 2011. Sample Collection was carried out after the steady state has been reached (around two months). The results showed that the efficiency of UASB reactors were comparable for the removal of chemical oxygen demand (COD), biological oxygen demand (BOD) and total suspended solids (TSS). On the other hand, the removal of fecal coliform (FC) did not exceed two log units in most cases. The results revealed that the quality of the effluent was not complying with WHO regulatory standards for reuse for irrigation. Consequently, post treatment step is of vital importance to protect the environment. [ABSTRACT FROM AUTHOR]

For a higher efficiency of the waste water treatment process in the mining industry from Romania, this paper indicates a mixed treatment of industrial mining waste water with domestic waste water from the mining unit. To perform this treatment process we used a complex treatment installation which meets in the same unit all the phases of municipal and industrial waste water treatment, namely: sewage clarification with the addition of reagents in vertical clearing tank; raw water treatment in a magnetic and electric field in order to potentiate the coagulation process; thickener drainage in screw filters; and clarified water passing through biological filters with added air for retaining organic matter, phosphates and nitrates. To optimize the waste water treatment process we used Evolutional Exploitation Method with Self-regulation Simplex which is a version of evolutional exploitation to approach the optimal domain. Scheduling of tests and interpretation of obtained results are based on so-called "simplex projections". To illustrate the principles of the method we consider y to represent the measured response and x1, x2 …xn variables that influence the response. Research is made to observe how the modification of these variables affects the response y to find values for these variables closer to the optimal domain. The optimization of the process using this method was adopted in order to minimize the response function. In order to apply this method to the complex treatment installation proposed by us we established that the technological parameters influencing the treatment process are: water flow, concentration of solid phase, concentration of ammonia nitrogen, organic matter content, air flow, exhaust thickeners flow. Applying the calculation algorithm for the centre of the start simplex, the unitary changes and the changes for each parameter, steps taken towards the optimal point are found by calculi and verified by experiments, without the need for logical thinking of the events. But having the sequence of parameters for each test and the obtained results we demonstrated that the Evolutional Exploitation Method with Self-regulation Simplex surprises the synergistic effect of process parameters on the response function. The complex treatment installation proposed by us can be used by any economic agent who has waste waters with similar characteristics. [ABSTRACT FROM AUTHOR]

A sequencing batch biofilm reactor (SBBR) treating domestic wastewater in low temperature (T [ABSTRACT FROM PUBLISHER]

Heavy metal contained in sewage sludge prevented the safety resource utilization of sludge and need to be disposed. Survey was conducted to find out main heavy metals in sludge generated in wastewater treatment plants in China and approximate content range of heavy metals in sewage sludge. The results showed that in domestic Cu and Zn were the main heavy metals with concentrations exceed the standard highly. And an order of Cr> Zn> Ni> Cu indicated the concentration situation of electroplating sewage sludge. There are a large amount of heavy metal ions in textile and dyeing industry wastewater sewage sluge, and the order of concentration was Zn> Cu> Pb> Ni> Cr> Cd. Cr was the most noteworthy heavy metal hazard heavy metal in tannery sludge. [ABSTRACT FROM PUBLISHER]