# A Modified Bio-Ecological Process for Rural Wastewater Treatment
###### Abstract  
Limited water resources and ensuring access to clean water are critical environmental challenges, especially for the developing world. In particular, rural domestic wastewater has become a significant source for the pollution of freshwater bodies. A modified bio-ecological A2O-wetland system for rural wastewater treatment consisting of a biological unit (anaerobic baffled reactor, anoxic tank and oxic unit, A2O) and an ecological unit (horizontal flow constructed wetland) was developed, and key performance indicators were identified. The bio-ecological treatment system showed high removal efficiency for pollutants, successfully achieving 91%, 85%, 78%, and 92% removal efficiencies for chemical oxygen demand (COD), ammonium (NH4-N), total nitrogen (TN), and total phosphorus (TP), respectively. The concentrations of pollutants in the effluent from the system were lower than the Class 1 A regulated values of the Chinese National Standard GB18918-2002. The system offered high removal efficiency, simple operation, and low energy consumption. The A2O-wetland is a good alternative for rural wastewater treatment systems.  
w +
Footnote †: journal: Applied Sciences  
_Article_  
A Modified Bio-Ecological Process for Rural Wastewater Treatment  
[PERSON], [PERSON], [PERSON], X.  
large investment costs for sewer networks [14]. For rural areas there is a need to adopt decentralized wastewater treatment methods, because wastewater collection in the villages is difficult due to the dispersed layout, small-scale, and complex geographic conditions [15].  
One of the main concerns regarding municipal wastewater discharge is the concentration of nutrient compounds [16]. These nutrients can stimulate the growth of aquatic vegetation in receiving water bodies, thereby decreasing the oxygen concentration [17]. Eutrophication of freshwaters bodies has gained increased attention, and a number of wastewater treatment methods have been developed to address this issue. Over the past few years some new technologies have been developed for rural or decentralized sewage treatments, such as the multistep A2O-H system [18], A2O-BAF system [19], five-step continuous flow activated sludge process (FSCFASP) [20], septic tanks [20], algal ponds [21], and soil trenches [22]. Most of these processes are selective or have operational issues. [PERSON] et al. [23] described an ANP (analytical network processes) approach to rank wastewater treatment technology set-ups for small communities by assessing multiple interdependences elements. Their results illustrated that constructed wetland is the most preferred alternative technology.  
Decentralized sanitation systems can have great success in rural and peri-urban areas that lack sanitation coverage [24]. Conventional wastewater technologies are expensive to build, maintain, and operate [24], especially for scattered populations. Therefore, it is important to develop economical, environmentally sustainable, and socially acceptable wastewater treatment technologies for rural areas [25]. A modified simple bio-ecological (A2O-CW) wastewater treatment system was developed in this study. The biological system consists of an anaerobic baffled reactor (ABR), anoxic tank, and an oxic unit with an ecological unit consisting of a constructed wetland. The system offered simple operation, low energy consumption, and high treatment efficiency.