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AbstractRecent legislation has led to stringent ammoniacal‐nitrogen consents and the need for first‐time sewage treatment in coastal areas where land is limited. This has led to the need to improve 'small footprint'sewage‐treatment processes (such as biological aerated filters) which can be used for carbonaceous treatment, nitrification, or for combined treatment. The removal of ammoniacal nitrogen in filters containing different sizes of Lytag medium and operated for combined carbonaceous treatment and nitrification, was compared at different hydraulic and volumetric loading rates. The results suggest that filters containing the smallest media size (2–4 mm), gave optimum nitrification at ammoniacal‐nitrogen loading rates up to 0.6 kg/m3. d. At higher loading rates there was a rapid decrease in nitrification for this size of medium but, with 2.8–5.6 mm medium, nitrification continued at loading rates up to 1 kg amm. N/m3 d. The filters containing larger media sizes (4–8 mm and 5.6–11.2 mm) exhibited low levels of nitrification above a loading rate of 0.2–0.4 kg amm. N/m3. d.

Facilities: Liverpool:2 m, FTN, OO:0.65, MLO:1 m, BAT, OAO:0.5 m, Swift, Mayall. Software: IRAF (v2.16.1; Tody 1993), Starlink (v2015B; Disney & Wallace 1982), APHOT (Pravec et al. 1994), HEASOFT (v6.16), XIMAGE (v4.5.1), XSPEC (v12.8.2; Arnaud 1996), XSELECT (v2.4c), R (R Development Core Team 2011). ; The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption 10 times, including yearly eruptions from 2008 to 2014. With a measured recurrence period of Prec = 351 ± 13 days (we believe the true value to be half of this) and a white dwarf very close to the Chandrasekhar limit, M31N 2008-12a has become the leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations of the 2013 and 2014 eruptions, we initiated a campaign to ensure early detection of the predicted 2015 eruption, which triggered ambitious ground- and space-based follow-up programs. In this paper we present the 2015 detection, visible to near-infrared photometry and visible spectroscopy, and ultraviolet and X-ray observations from the Swift observatory. The LCOGT 2 m (Hawaii) discovered the 2015 eruption, estimated to have commenced at August 28.28 ± 0.12 UT. The 2013–2015 eruptions are remarkably similar at all wavelengths. New early spectroscopic observations reveal short-lived emission from material with velocities ∼13,000 km s^−1, possibly collimated outflows. Photometric and spectroscopic observations of the eruption provide strong evidence supporting a red giant donor. An apparently stochastic variability during the early supersoft X-ray phase was comparable in amplitude and duration to past eruptions, but the 2013 and 2015 eruptions show evidence of a brief flux dip during this phase. The multi-eruption Swift/XRT spectra show tentative evidence of high-ionization emission lines above a high-temperature continuum. Following Henze et al. (2015a), the updated recurrence period based on all known eruptions is Prec = 174 ± 10 days, and we expect the next eruption of M31N 2008-12a to occur around 2016 mid-September. ; A.F.V., and V.P.G. acknowledge support from RFBR Grant No. 16 February 00758. J.F., J.J., and G.S. acknowledge support from Spanish Ministry of Economy and Competitiveness (MINECO) grant AYA2014-59084-P, the E.U. FEDER funds, and AGAUR/Generalitat de Catalunya grant SGR0038/2014. S.F. acknowledges support from the Russian Scientific Foundation (grant N 14-50-00043) and the Russian Government Program of Competitive Growth of Kazan Federal University. M. Henze acknowledges the support of the Spanish MINECO under grant FDPI-2013-16933. M. Hernanz acknowledges MINECO support under grant ESP2014-56003-R.K.H. was supported by the project RVO:67985815. J.P.O. and K.L.P. acknowledge funding from the UK Space Agency. VARMR acknowledges financial support from the Radboud Excellence Initiative. S.C.W. acknowledges a visiting research fellowship at LJMU. This work has been supported in part by NSF grant AST-1009566 and NASA grant HST-Go-14125.012. ; Peer-reviewed ; Post-print