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A full-scale anaerobic side-stream reactor (ASSR) for sludge reduction was monitored in terms of sludge production and compared with the previous conventional activated sludge configuration (CAS). A detailed solid mass balance was calculated on the whole full-scale plant to estimate the sludge reduction associated with the ASSR. The activity of the biomass, which undergoes alternation of aerobic and anaerobic conditions, was investigated by the respirometric test. The ASSR promoted a reduction of heterotrophic biomass activity and the substrate consumption rate in the activated sludge implemented with ASSR (AS + ASSR) was 36% smaller than in the CAS period. The solid mass balance indicated a sludge reduction of 28%. During the 270-day operation, the observed sludge yield passed from 0.438 kgTSS/kgCOD in the CAS to 0.315 in the AS + ASSR configuration. The solubilization of chemical oxygen demand (COD), NH4+-N and orthophosphate were verified under anaerobic conditions. The results suggest that the possible mechanisms of sludge reduction were the increase of the system sludge retention time (SRT) by ASSR addition, and the reduction in heterotrophic biomass activity added to the organic compounds' hydrolysis.

Brazil is one of the most important countries in pork production worldwide, ranking third. This activity has an important role in the national economic scenario. However, the fast growth of this activity has caused major environmental impacts, especially in developing countries. The large amount of nitrogen and phosphorus compounds found in pig manure has caused ecological imbalances, with eutrophication of major river basins in the producing regions. Moreover, much of the pig production in developing countries occurs on small farms, and therefore causes diffuse pollution. Therefore, duckweed pond have been successfully used in the swine waste polishing, generating further a biomass with high protein content. The present study evaluated the efficiency of two full scale duckweed ponds for the polishing of a small pig farm effluent, biomass yield and crude protein (CP) content. Duckweed pond series received the effluent from a biodigester-storage pond, with a flow rate of 1 m 3 /day (chemical oxygen demand rate ¼ 186 kg/ha day) produced by 300 animals. After 1 year a great improvement of effluent quality was observed, with removal of 96% of total Kjeldahl nitrogen (TKN) and 89% of total phosphorus (TP), on average. Nitrogen removal rate is one of the highest ever found (4.4 g TKN/m 2 day). Also, the dissolved oxygen rose from 0.0 to 3.0 mg/L.The two ponds produced together over 13 tons of fresh biomass (90.5% moisture), with 35% of CP content, which represents a productivity of 24 tonsCP/ha year. Due to the high rate of nutrient

Purpose Olive oil industry is a growing industrial sector in Mediterranean countries. Unfortunately, about 30-35% of total olive weight is discarded as olive pomace (OP), a highly environmental-polluting solid waste.OP is mostly used for composting and production of animal feed; nevertheless, the high oil content, phenolic compounds and fiber contents in addition to its low protein content represent major obstacles for both applications. So, the present study was conducted to evaluate the role of solid state fermentation (SSF) in OP using Kluyveromyces marxianus NRRL Y-8281 yeast on the chemical composition and tannin content of OP in a trial for its bioconversion into a value-added animal feed. Methods Chemical composition, nutritive and energetic values, tannin and gallic acid contents of unfermented and fermented olive pomace were investigated. Results The fermentation altered the chemical composition of OP, so that crude fiber was decreased by 8.56%, while crude protein, fat and carbohydrate contents were increased by 2.74, 2.63 and 3.57%, respectively. Moreover, the effect of fermentation on cell wall constituents, gross energy, digestible energy, total digestible nutrients and digestible crude protein was evaluated. Furthermore, HPLC analysis revealed that K. marxianus mediated fermentation of OP resulted in a sharp decrease in tannin content by 96.75% with 2.8 times increase in gallic acid concentration. Conclusion SSF of OP by K. marxianus does not only eliminate the environmental pollution resulting from its accumulation, but also presents a new eco-friendly valorization technique which leaves OP with an altered chemical composition allowing its use as animal feed or compost.

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-The following sludge reduction alternatives were tested in wastewater biological reactors: oxic-settling-anaerobic (OSA-process); ultrasonic disintegration (UD); chlorination (CH); 3,3',4',5-tetrachlorosalicylanilide (TCS); and folic acid (FA). Compared to the control system, UD reduced 55% of the sludge production, and greater substrate and nutrient removal efficiency was achieved. CH worsened the sludge settleability and increased the SVI values; the system achieved 25% of sludge reduction. OSA showed 50% and 60% of sludge reduction after 16 and 10 hours under anaerobic conditions, respectively. The observed sludge yield during TCS addition was decreased by 40%, and the sludge settleability worsened. FA presented the highest sludge reduction (75%), and the system improved the nutrient removal efficiency by 30% compared to the control system and maintained the sludge properties. Acute toxicity conducted with Daphnia magna classified the effluent from the sludge reduction systems as non-toxic for discharge into water sources.

NO-production was investigated during nitrogen removal using aerobic granular sludge (AGS) technology. A pilot sequencing batch reactor (SBR) with AGS achieved an effluent in accordance with national discharge limits, although presented a nitrite accumulation rate of 95.79% with no simultaneous nitrification-denitrification. NO production was 2.06 mg L during the anoxic phase, with NO emission during air pulses and the aeration phase of 1.6% of the nitrogen loading rate. Batch tests with AGS from the pilot reactor verified that at the greatest COD/N ratio (1.55), the NO production (1.08 mgNO-N L) and consumption (up to 0.05 mgNO-N L), resulted in the lowest remaining dissolved NO (0.03 mgNO-N L), stripping the minimum NO gas (0.018 mgNO-N L). Conversely, the carbon supply shortage, under low C/N ratios, increased NO emission (0.040 mgNO-N L), due to incomplete denitrification. High abundance of ammonia-oxidizing and low abundance of nitrite-oxidizing bacteria were found, corroborating the fact of partial nitrification. A denitrifying heterotrophic community, represented mainly by Pseudoxanthomonas, was predominant in the AGS. Overall, the AGS showed stable partial nitrification ability representing capital and operating cost savings. The SBR operation flexibility could be advantageous for controlling NO emissions, and extending the anoxic phase would benefit complete denitrification in cases of low C/N influents.