image scrambling;scrambling degree;gray scale;signal-noise ratio
Xudong Wang · Journal of Xi'an University of Arts and Science · 2013
With the improvement of people's living standard,domestic sewage has become an important pollution source.Centralized wastewater collection and treatment systems are costly to build and operate,especially in areas with low population densities and dispersed households.Alternatively,the decentralized system is not only a long-term solution for small communities but is more reliable and cost effective.This paper presents a review of the various recent decentralized domestic sewage treatment systems,including septic tanks,natural wastewater treatment system and artificial wastewater treatment system.The most suitable decentralized system can be chosen accordingly.