Treatment Of Ship Domestic Sewage By Ultrasonic Enhanced Technology

Increasingly frequent communication activities between the countries in the world have promoted the rapid development of the shipping industry,A large number of sewage discharge on the marine environment caused serious harm.For this reason,the International Maritime Organization（IMO）tended more stringently to the requirement of ship sewage discharge standard.Currently,the ship sewage treatment technologies include biological,physical and chemical methods.Among them,biotechnology and its process applicated more frequently,but these processes have many limitations on the removal of organic matters,Therefore,it is urgent to find an effective technique which can improve the reformation of the original equipment on the ship for improving the treatment effect on ship domestic sewage.Ultrasound technology is a new type of advanced oxidation technology,which developed in recent years and has the characteristics of no secondary pollution and broad research prospects.Ultrasound Enhancement Technology was adopted to treat artificial ship sewage in this work.Meanwhile,The influence factors of ultrasonic strength treatment and the removal mechanism of organic matters were investigated and the conditions for optimal ultrasound parameters were optimized,which can provided support for the practical application.It can be obtained that the individual ultrasonic technology can remove organics from ship domestic sewage effectively.As the increase of frequency,the COD removal rate was first increased and then decreased,and the optimal ultrasound frequency was 40kHz.As the increase of power,the COD removal rate was first increased and then decreased,and the optimal ultrasound power was 90w.COD removal rate was increased with the extension of irradiation time under the best conditions of ultrasonic frequency and ultrasonic power,as long as the treatment time is long enough,organics will be eventually mineralized into CO₂,H₂O and other mineral salts.Sewage turbidity was increased gradually with the treatment time extending,which indicated that ultrasound treatment on turbidity removal was ineffective.Ultrasound enhanced on coagulation was investigated in this experiment.PAC,PFS,and FeSO₄ were choosen for conventional coagulation test research.The orthogonal test was studied for ptimizing ultrasound parameters of each coagulant.Through the response surface and the mechanism analysis on ultrasound enhanced coagulation,the power at of 90w and ultrasonic frequency at of 40kHz were optimal ultrasound parameters of the three coagulants,and each coagulant had different ultrasonic irradiation time.When ultrasonic irradiation time of PAC was 1min,the COD removal efficiency reached 35.29%,which was increased 10%compared with coagulation treatment alone.When ultrasonic irradiation time of PFS was2.5min,the COD removal efficiency reached 28.77%which was increased 10%compared with coagulation treatment alone.And when ultrasonic irradiation time of Fe SO₄ was 2.85min,the COD removal efficiency reached 25.99%which was increased 10%compared with coagulation treatment alone.In addition,ultrasound strengthen Fenton was used to treat ship domestic sewage.Fenton method alone was studied to determine that when the dosage of 30%H₂O₂ was 0.08mol/L,and COD removal rate reached 66.13%.The effect of Fenton oxidation of organic compounds was better.For the combined effect of ultrasound and Fenton,the COD removal rate reached92.71%,and the turbidity removal rate reached 97.14%,when ultrasonic frequency was40kHz,ultrasonic power was 106w,the irradiation time was 40min,which indicated that the effect of ultrasound enhanced on Fenton was significant.