The efficiency of nitrogen removal in synthetic laundry wastewater using a submerged membrane bioreactor at different total nitrogen volume loadings and MLSS concentrations

Abstract

Svrha rada bila je odrediti učinak različitih volumenskih opterećenja ukupnim dušikom i različitih koncentracija aktivnog mulja (MLSS - mixed liquor suspended solids) u uronjenom membranskom bioreaktoru na nitrifikaciju i učinkovitost uklanjanja dušika iz meke sintetičke otpadne vode. U prvom dijelu istraživanja volumensko opterećenje ukupnim dušikom povećano je s 0,063 na 0,315 g L-1 d-1. Aktivni mulj nije uklonjen iz reaktora i zato se koncentracija povećala s početnih 4 g L-1 na maksimalnu vrijednost od 25,6 g L-1. Rezultati uklanjanja ukupnog dušika pokazali su da je učinak obrade bio najveći pri volumenskom opterećenja ukupnim dušikom od 19 g L-1 d-1 s učinkom uklanjanja od 84 %. U drugom dijelu istraživanja volumensko opterećenje ukupnim dušikom bilo je konstantno od 0,19 g L-1 d-1, a koncentracije aktivnog mulja mijenjale su se između 10 i 15 g L-1. Rezultati u tom dijelu istraživanja pokazuju da se nitrifikacija nije dogodila kada je koncentracija aktivnog mulja bila 10 g L-1 i da je nitrifikacija počela kada se povećala koncentracija aktiviranog mulja. Istraživanje pokazuje povezanost između koncentracije biomase i stupnja nitrifikacije u membranskom bioreaktoru (MBR).The aim of this study was to determine the effect of various total nitrogen volume loadings and various mixed liquor suspended solids (MLSS) concentrations in the submerged membrane bioreactor on the nitrification and the efficiency of nitrogen removal from soft synthetic wastewater. In the first part of the research the total nitrogen volume loading was increased from 0.063 to 0.315 g L-1 d-1. The activated sludge was not removed from the reactor and therefore the concentration increased from the initial 4 g L-1 to a maximum value of 25.6 g L-1. The results for removal of total nitrogen showed that the treatment effect was highest at the total nitrogen volume loading of 0.19 g L-1 d-1, with 84 % removal efficiency. In the second part of the research the total nitrogen volume loading was held constant at 0.19 g L-1 d-1 and the MLSS concentrations were varied between 10 and 15 g L-1. The results in this part of the research showed that nitrification did not occur when the activated sludge concentration was 10 g L-1 and that nitrification started when the activated sludge concentration increased. The research shows the connection between biomass concentration and nitrification degree in the MBR