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This study treated sanitary landfill leachate and was conducted in a pilot-scale system composed of three serial ponds (P1, P2 and P3), followed by a rock filter, in order to evaluate the microbial consortium influence on system performance and to investigate microorganism dynamics in the process. The system was broken into three stages, with a continuous flow rate (Q = 200 L d-1) for 43 weeks. The stages were as follows: conventional operation (stage I), 12 h aeration in P2 (stage II), and 18 h aeration in P2 (stage III). The results showed the possibilities for treating landfill leachate, presenting an average efficiency of 75% for both filtered biochemical oxygen demand and ammonium. At the end of stage III, the ammonium concentration was 6 mg L-1, which is lower than that established by Brazilian regulations for wastewater discharge (CONAMA 430/2011). The aeration applied in P2 led to a change in the microbial consortia during the second and third stage, which influenced the quality of the final effluent. The best performance was seen in stage III, where the system showed high microbial diversity, including the presence of nitrifying bacteria. [ABSTRACT FROM AUTHOR]

In this paper an extended version of IWA's Activated Sludge Model No 3 (ASM3) was developed to simulate processes in waste stabilisation ponds (WSP). The model modifications included the integration of algae biomass and gas transfer processes for oxygen, carbon dioxide and ammonia depending on wind velocity and a simple ionic equilibrium. The model was applied to a pilot-scale WSP system operated in the city of Florianópolis (Brazil). The system was used to treat leachate from a municipal waste landfill. Mean influent concentrations to the facultative pond of 1,456 gCOD/m3 and 505 gNH4-N/m3 were measured. Experimental results indicated an ammonia nitrogen removal of 89.5% with negligible rates of nitrification but intensive ammonia stripping to the atmosphere. Measured data was used in the simulations to consider the impact of wind velocity on oxygen input of 11.1 to 14.4 gO2/(m2 d) and sun radiation on photosynthesis. Good results for pH and ammonia removal were achieved with mean stripping rates of 18.2 and 4.5 gN/(m2 d) for the facultative and maturation pond respectively. Based on measured chlorophyll a concentrations and depending on light intensity and TSS concentration it was possible to model algae concentrations. [ABSTRACT FROM AUTHOR]

Stabilization ponds used for the treatment of piggery wastes accumulate sludge over time, which is commonly used in agriculture. The objective of this study was to evaluate the agronomic potential of this kind of sludge. The samplings were collected in two different phases. The first in two anaerobic ponds (AP1 and AP2) and in one facultative pond with 5 transverse baffles and, the second in the same facultative pond with aeration. The removed sludge of AP1 and AP2 was characterized as rich sludge in volatile solids and with low stabilization, there was a great accumulation of the total phosphorus in the sludge of AP2. The facultative pond presented greater retention of nutrients in the sludge in relation to the anaerobic ponds. The annual accumulation of sludge was 13.3 cm/year in the AP1 and 6.70 cm/year in the AP2, while in the pond with aeration this was on the average of 0.5 cm/year, due to the aeration regime. The sludge can be used as a fertilizer in agriculture, if the chemical characteristics of the soil are taken into account so as to avoid the accumulation of nutrients and damage to plants. [ABSTRACT FROM AUTHOR]

This work investigates the optimal management of water hyacinth ponds for the improvement of piggery waste treatment. The optimal harvesting strategy for the water hyacinth was studied using a single mathematical model. The water hyacinth optimal harvesting problem was formulated as an optimal control problem that was solved by application of Pontryagin's Maximum Principle. The optimization of the water hyacinth control in the pond indicates that the plant density should be reduced whenever it reaches half of the maximum capacity for growth. Two experimental systems were used to validate the mathematical model, one in real scale and the other in pilot scale. The results demonstrated the feasibility of the proposed harvesting strategy. For example, a comparison of the total nitrogen removal in the different pilot ponds confirmed the modeling results, in that the performance of the pond maintained with 50% water hyacinth cover was better than the others. [ABSTRACT FROM AUTHOR]

This work concerned the application of anaerobic ponds for the primary treatment of urban wastewater in a Mediterranean climate. It was carried out on anaerobic ponds at large scale in Mèze (France). The anaerobic ponds constitute a good primary treatment with the removal of 55% of SS and 30% of BOD5, with a small surface area. The accumulation rate of sludge was only 0.017 m³/capita.year, due to their intensive anaerobic degradation. The anaerobic digestion reached equilibrium after one year of operation. The accumulation of sludge then showed seasonal variations with a substantial accumulation in winter and the digestion of the stock in summer. This change can be related to the influence of the temperature on methanogenesis. The production of biogas (83% CH4) was measured by gas collectors especially developed for this study and was also strongly dependent on temperature. The mass balance of carbon showed that 74% of the removed organic carbon was converted into CH4, 13% into dissolved inorganic carbon and 15% was stored in sludge. However, the anaerobic ponds presented a risk of creating odor nuisances with the emission of H2S. [ABSTRACT FROM AUTHOR]

Presents a study to evaluate the performance of a baffled facultative pond for the treatment of piggery wastes. Use of an equalizer, one decanter, two anaerobic ponds, one facultative pond, and one maturation pond with water hyacinths; How research was conducted in the west region of Santa Catarina, Brazil; Findings that the first baffle in the facultative pond was mainly responsible for the efficiency of this pond.