The treatment of run-off from a fertiliser plant for nitrification, denitrification and phosphorus removal by use of constructed wetlands: a demonstration study

Beet molasses – desugarization, composition, properties and application possibilities

Despite the fall in sugar production in Europe, molasses still remains a valuable raw material in many areas. Installation of modern techniques into sugar technology (e.g. bioethanol fermentation or chromatographic separation) has meant that sugar technologists require different final properties and quality of this by-product compared to traditional sugar technology. This paper describes basic mathematical equations and results from a proof mathematical model of C sugar cooling crystallization. Great attention is paid to the detailed composition and physicochemical properties of molasses, knowledge of which is necessary both for novel and existing molasses applications.

Variation of dissolved oxygen and redox potential and their correlation with microbial population along a novel horizontal subsurface flow wetland

AIMS

This study was conducted to evaluate the performance of a novel horizontal subsurface flow wetland (HSFW) in naturally improving the dissolved oxygen (DO) and the impact on redox condition, microbial activity and the nitrogen removal in the HSFW bed.

MATERIALS AND METHODS

The HSFW, equipped with cascaded natural aeration ditches (NADs), was the second stage of a hybrid constructed wetland (CW) after vertical-baffled flow wetland beds. The performances of the HSFW for organics and nitrogen removal in a full-scale hybrid CW system treating municipal wastewater for more than three years have been analysed. The spatial distributions of the oxidation-reduction potential (ORP), DO, microbial population density and specific oxygen uptake rate were determined, and their correlations were analysed in one selected section of the HSFW bed.

RESULTS

A 7-m-long shallow NAD increased the DO concentration from 0.28 mg O2 L(-1) to 3.80 mg O2 L(-1) and the ORP from +37.3 mV to +247.7 mV, creating an aerobic zone with a hydraulic retention time (HRT) of 0.5 h and an anoxic zone of another 0.5 h in series in the subsequent wetland bed. For the whole HSFW with three NADs, the macro aerobic and anoxic environment with a total HRT of 3 h can be created.

CONCLUSIONS

The unique DO distribution in HSFW may contribute to an optimum environment for partial nitrification and anammox, and obtain a high performance for nitrogen removal. Correlation analysis showed that the microbial activity in the HSFW relied obviously on the redox condition.