Enhanced Denitrification of Integrated Sewage Treatment System by Supplementing Denitrifying Carbon Source

Integrated sewage treatment system (ISTY) is a new technology for rural domestic sewage treatment. In the ISTY, the carbon source in the denitrification stage is often insufficient, affecting the denitrification efficiency. In order to improve the denitrification efficiency, several commonly available agricultural wastes, peanut shell (PS), sawdust (SD), peat (PT), and their mixtures (MT), were selected as supplementary carbon sources in the denitrification stage of ISTY to study the denitrification efficiency. Results show that PS exhibited a high carbon release capacity. PS released an enormous amount of carbon in 144 h, and the cumulative total organic carbon was 41.99 ± 0.7 mg/(g·L). The optimum carbon source dosage was 3 g/L, the nitrate removal rates of PS exceeded 95% after 48 h, and the denitrification rates were 9.35 mg/(g·L), which were 63.92% higher than that of the control group. After running the ISTY for 120 h, and with PS as supplementary carbon sources, the removal rate of TN increased from 29.76% to 83.86%. At the genus level, the dominant denitrifying bacteria in ISTY, after adding PS, were Pseudomonas and Cupriavidus, accounting for 78.68%, an increase of 72.90% compared with the control group. This evidence suggested that PS can obviously enhance the denitrification efficiency of the ISTY as a supplementary carbon source.

Performance evaluation of the sewage treatment system SANEBOX

Sewage treatment processes have been increasingly the target of research aimed at developing solutions that meet environmental standards at lower costs for society. The generation of sanitary sewage and its final release, without treatment or with inefficient treatment in sewage networks, lakes, rivers or oceans have aggravated the quality of water resources and put at risk the health of the population given water-delivery diseases. This article aimed to evaluate the results obtained by the Treatment System called SANEBOX, for the treatment of sanitary sewage, considering a period of two years of monitoring campaigns in it. Additionally, a comparison is made in terms of achieving environmental goals of this System with other conventional technologies that have usually been implemented in Brazil. The guiding parameters for this evaluation were Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Sedimentable Materials (SM), Total Suspension Solids (TSS), Vegetable or Animal Oils and Greases (OGv/a), Tensoactive Substances That React to Methylene Blue (MBAS), Ammoniacal Nitrogen (N-NH4+) and Phosphorus (P). The results obtained show that the SANEBOX System has similar performance and, in some parameters, much higher than the conventional Sewage Treatment System, either in terms of removal of pollutants, or in terms of occupied area, energy consumption and nuisance to neighborhoods by bad odors.

Selection of chemical phosphorus removal scheme based on Analytic Hierarchy Process

Chemical precipitation phosphorus removal process can improve the phosphorus removal effect of sewage treatment system to meet the increasingly stringent discharge standards. In order to assist designers in selecting reasonable chemical phosphorus removal schemes, the analytic hierarchy process was applied to quantitatively evaluate each chemical phosphorus removal scheme from four aspects: water treatment effect, operation cost, operation and management difficulty and environmental impact. Finally, combined with an engineering example, the process of analytic hierarchy process quantitative evaluation of chemical phosphorus removal scheme and the method of selecting the optimal scheme are introduced, which provides a reference for the selection of chemical phosphorus removal scheme in engineering.