G. Bortone

Biological phosphorus removal by pure culture of Lampropedia spp.

Abstract Lampropedia spp. is a Gram-negative, Neisser-positive coccus that was isolated from EBPR (enhanced biological phosphate removal) activated sludge laboratory plants operating on dairy and piggery wastewaters. In aerobic growth tests carried out on sodium acetate, Lampropedia spp. stored PHB up to 12% w/w. Biomass yield was estimated at 0.55 g VSS.g−1 HAc and specific growth rate at 0.045 h−1. The experimental maximum acetic acid removal rate was 71.86 mg HAc.g−1 VSS.h−1 with a semisaturation constant of 71.78 mg.l−1. Batch tests were carried out to check whether Lampropedia spp. was capable of enhanced biological phosphorus removal. Under anaerobic conditions, Lampropedia spp. sequestered acetate and stored PHB with an average conversion factor of 0.33 mg PHB.mg−1 HAc. The measured maximum PHB storage capacity was 31% w/w, with a maximum specific PHB accumulation rate of 17 mg PHB.g−1 VSS.h−1 and a specific anaerobic acetate uptake rate of 57 mg HAc.g−1 VSS.h−1. The experimental ratio between phosphorus released and acetate taken up was low, on average 0.044 mg PO4-P.mg−1 HAc, with a specific rate ranging from 1.7 to 3.6 mg PO4-P.g−1 VSS.h−1 at pH 7.5. Despite the low figure, fractionation analyses showed that in anaerobic conditions the released phosphate comes from cell polyphosphate degradation. Therefore, all the results allow us to conclude that Lampropedia spp. can be classified amongst the phosphorus accumulating bacteria

Integrated anaerobic/aerobic biological treatment for intensive swine production

Manure processing could help farmers to effectively manage nitrogen (N) surplus load. Many pig farms have to treat wastewater. Piggery wastewater treatment is a complex challenge, due to the high COD and N concentrations and low C/N ratio. Anaerobic digestion (AD) could be a convenient pre-treatment, particularly from the energetic view point and farm income, but this causes further reduction of C/N ratio and makes denitrification difficult. N removal can only be obtained integrating anaerobic/aerobic treatment by taking into account the best use of electron donors. Experiences gained in Italy during development of integrated biological treatment approaches for swine manure, from bench to full scale, are reported in this paper. Solid/liquid separation as pre-treatment of raw manure is an efficient strategy to facilitate liquid fraction treatment without significantly lowering C/N ratio. In Italy, two full scale SBRs showed excellent efficiency and reliability. Current renewable energy policy and incentives makes economically attractive the application of AD to the separated solid fraction using high solid anaerobic digester (HSAD) technology. Economic evaluation showed that energy production can reduce costs up to 60%, making sustainable the overall treatment.

The fertilizer value of agricultural manure: Simple rapid methods of assessment

This paper presents the results of a series of analytical tests performed on pig and dairy cattle manure in order to establish the extent of the correlation between: dry matter (TS) and specific gravity (SG); TS and total Kjeldhal nitrogen (TKN) and total phosphorus (Pt); SG and TKN and Pt. In addition, two N-meters for field use were also used to estimate the ammonium (NH 4 -H) content. All the variables (TS, SG, TKN, Pt, NH 4 -N) show a high index of correlation for both the pig and dairy cattle slurry and the linear relations applied proved adequate in all cases. Though the precision of the equations is not very high, the estimate for TKN and Pt content, obtained from the relationship between the SG and these elements is nevertheless acceptable for practical farm use of animal manure.

Fate of residuals in nitrification-denitrification treatment of piggery wastewaters

Abstract A careful appraisal of piggery wastewaters should be made mainly because of their high content of organic constituents together with the nitrogen and stringent effluent limitations involved. Specific emphasis should be given to the COD of the wastewater as it contains, aside from a biodegradable portion, a residual fraction which persists throughout the treatment process. Experimental evaluations indicated that the effluent of a laboratory-scale SBR contained significant amounts of non-biodegradable COD. Since SBR was primarily operated to achieve nitrification-denitrification, a method previously developed for the assessment of the influent soluble inert COD, S 1 was modified in a way to reflect the possible impact of the nitrification and denitrification processes. The paper also summarizes the performance of SBR with respect to its nitrogen removal potential from piggery wastewaters.

Post-treatments of anaerobic effluents

Post-treatments are necessary if anaerobic effluents need to be discharged into surface waters, because anaerobic digestion alone is not able to produce effluents that can meet the discharge standards applied in most industrialized countries, particularly for suspended solids, particulate COD, nitrogen, phosphorus and sulphides. This paper has the aim to present some results obtained in the recent years in our laboratory, where different comprehensive processes that include anaerobic digestion have been studied. Discussion will regard: 1) the ANANOX (ANaerobic-ANoxic-OXic) process for the treatment of municipal wastewater; 2) a process studied for the biological removal of C, N and P from piggery wastewater that has a hybrid anaerobic/anoxic reactor as the first treatment step; 3) the use of a Sequencing Batch Reactor for the post-treatment of digested cheese whey mixed with cheese factory cleaning waters.

Nitrification and denitrification in activated-sludge plants for pig slurry and wastewater from cheese dairies

Abstract Considerable amounts of pig slurry should be sent for purification in areas where there is a high concentration of pig farms (in north Italian regions, for instance). One solution is the development of plants whose objective is the obligatory pretreatment of this wastewater before discharge into sewage pipes. In a full-scale plant on a dairy farm, which treats piggery and dairy wastewaters and sewage, by reducing the DO concentration and increasing the biomass concentration, an increase in the removal of COD and N and simultaneous nitrification and denitrification were obtained. Simultaneous nitrification-denitrification was observed in a pilot plant or treating anaerobically-pretreated piggery wastewater, and this is also described.