Phosphorus removal from domestic wastewater by Nelumbo nucifera Gaertn. and Cyperus alternifolius L.

Domestic wastewater is a source of phosphorus contamination that causes eutrophication when it contaminates aquatic environments. Nelumbo nucifera Gaertn. and Cyperus alternifolius L. were applied for phosphorus removal from domestic wastewater. From the study, phosphorus in domestic wastewater was removed from the initial concentration of 1.038 ± 0.001 mgL(-1) to 0.094 ± 0.001 and 0.048 ± 0.004 mgL(-1) by N. nucifera and C. alternifolius, respectively, within 5 days. In addition, total Kjeldahl nitrogen (TKN) and chemical oxygen demand (COD) also decreased when wetland systems were applied the same as treatment with conventional method (chemical + activated sludge process). However, the plant removed TDS better than the conventional method. During 5 cycles of exposure, the two plants still survived and were healthy. The weight of plants increased after the experiment from 4060 ± 0.05 g to 4820 ± 0.17 g of N. nucifera, and from 4000 ± 0.00 g to 4600 ± 0.14 g of C. alternifolius. Phosphorus content also increased in both plants after the experiment. However, in the wetland system, phosphorus was removed mainly by the soil, followed by the plants, and then microorganisms. The domain group in the microbial community of both wetland systems was Pseudomas sp.

Effect of moisture content on fed batch composting reactor of vegetable and fruit wastes.

Vegetable and fruit wastes mixed with sawdust were composted in a laboratory scale reactor by controlling the waste feeding rate at 21 kg m(-3) day(-1) and aeration rate at 10.6 l m(-3) min(-1). The effects of initial moisture content on organic matter degradation and process performance of fed batch composting were investigated. The absolute amount of removal, removal percentage, and removal rate of dry mass obtained were substantially different among the initial moisture contents. The rapid rise of moisture content and the lowest absolute amount of removal observed were achieved in the 50% condition. The initial moisture content yielding the largest absolute amount of removal in both feeding and curing stage was 30% whereas the removal percentage and rate constant of waste decomposition were highest in the 50% condition. Examined by traditional soil physics method, the moisture content at 50-55% was suitable for satisfying the degree of free air space (65-70%) of compost during the fed batch composting. Most degradable organic matter was mainly consumed in the feeding stage as indicated by a higher removal rate of dry mass in all cases. It is recommended that the initial moisture content of 30% and mode of aeration and agitation should be adopted for achieving practical fed batch composting of vegetable and fruit wastes. The study also demonstrated that the composting kinetics of vegetable and fruit wastes mixed with sawdust can be described by a first order model.