pH mõju nitritlämmastiku akumulatsioonile magedaveelises denitrifikatsioonisüsteemis

Denitrifikatsioon on bioloogiline lämmastikuärastusprotsess, mis teatud tingimustes kulgeb mittetäielikult, tekitades nitriti akumulatsiooni. Töös uuriti pH mõju antud nähtusele, teostati annuskatsed (kuni 6 tundi) ning pilootkatsed (48 päeva). Annuskatsetes täheldati pH iseeneslikku tõusu väärtuse 9,5 poole, millega kaasnes ka oluline nitriti akumulatsiooni tõus. Akumulatsioon võib tuleneda nitriti reduktaasi osalisest inhibeeritusest kõrge pH väärtuse poolt, mille tõttu osa toodetud nitritist jääb keskkonda alles. Pilootkatsetes saavutati katse alguses sarnased tulemused, kuid biomassi kohanedes kõrge pH väärtusega nitriti akumulatsioon vähenes. Nitriti akumulatsiooni kasutamiseks tehnoloogilise protsessina soovitatakse biomassi pidevalt reaktoris vahetada, et vältida selle kohastumist tugevalt aluselise keskkonnaga

SMOOTH TEMPERATURE DECREASING FOR NITROGEN REMOVAL IN COLD (9-15° C) ANAMMOX BIOFILM REACTOR TESTS

For N-rich wastewater treatment the anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used. In a deammonification moving bed biofilm reactor (MBBR) a maximum total nitrogen removal rate (TNRR) of 1.5 g N m-2d-1(0.6 kg N m-3d-1) was achieved. During biofilm cultivation, temperature was gradually lowered by 0.5° C per week, and a similar TNRR was sustained at 15° C. qPCR analysis showed an increase in Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15° C. Fluctuations in TNRR were rather related to changes in influent NH4+ concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively) with anammox temperature constants ranging 1.3-1.6. After biomass was adapted to 15° C, the decrease in TNRR in batch tests at 9° C was lower (15-20%) than for biomass adapted to 17-18° C. Our experiments show that a biofilm of a deammonification reactor adapted to 15° C successfully tolerates shortterm cold shocks down to 9° C retaining a high TNRR

Nitric oxide for anammox recovery in a nitrite-inhibited deammonification system

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HELCOM Thematic assessment of hazardous substances, marine litter, underwater noise and non-indigenous species 2016-2021. Baltic Sea Environment Proceedings n°190

The production of this report was carried out through the HELCOM Project for the development of the Third Holistic Assessment of the Baltic Sea (HOLAS 3). The work builds on the previous assessment (HOLAS II) and methodologies, evaluations and assessments included in this report have been directly contributed to by the HELCOM BLUES project, the Baltic Data Flows project, the COMPLETE project, the COMPLETE PLUS project, and the PreEMPT project