Nonlinearity,　uncertainties,　and　disturbances　exist　extensively　in　wastewater　treatment　processes　(WWTPs),　which　result　in　control　performance　degradation　and　critical　instability.　To　solve　this　problem,　an　efficient　self-organizing　sliding-mode　controller　(SOSMC)　is　proposed　to　achieve　acceptable　and　stable　control　performance　for　WWTPs.　The　novelties　of　SOSMC　involve:　1)　a　practical　control　strategy,　combining　advantages　of　sliding-mode　control　and　fuzzy-neural　network,　was　designed　to　suppress　the　disturbances　and　uncertainties　of　WWTPs;　2)　a　self-organizing　mechanism,　based　on　the　tracking　error　and　structure　complexity,　was　developed　to　alleviate　the　chattering　phenomenon　of　SOSMC　and　improve　the　control　performance;　and　3)　the　stability　analysis,　including　the　fixed　and　adaptive　structures,　was　given　to　ensure　the　successful　applications　of　SOSMC.　Finally,　experimental　investigations　on　a　real　WWTP　are　employed　to　validate　the　merits　of　the　proposed　method.