Residual Sludge Reduction By Synergistic Effects Of Nano-sized Magnetic Particles And Uncoupler

Activated sludge process had effective treatment and inexpensive etc. advantages that it used most extensively in the large domestic wastewater treatment plant, but excess sludge production is highly. When the problem comes to how to realized sludge reduction at resource, in this paper, take advantage of uncoupler can block biological anabolic to decrease the excess sludge production. And use nano-sized magnetic particles high adsorption performance and high saturation magnetic force two characteristics to make up the shot of the biodegradability and settling properties of the activated sludge were decreased after uncoupler used in activated sludge process result in low to zero excess sludge discharge from wastewater treatment plant.In the present investigation, uncoupler and nano-sized magnetic particles were added simultaneously to a sequencing batch reactor for exploring their synergistic effects to the characteristics of activated sludge, process performance, microbial population structure and2,4,5-Trichlorophenol(TCP) migration transformation and analyzing the feasibility of realized sludge reduction with uncoupler and nano-sized magnetic particles. The conclusions are as follow:(1) Process performance and sludge settling property of Sequencing Batch Reactor Activated Sludge Process were improved significantly after the nano-sized magnetic particles were added. Its increased by increasing the the nano-sized magnetic particles addition amount, and no longer improve significantly when dosing quantity higher than0.8g·L-1, consideration of economic factors, the best nano-sized magnetic particles dosing quantity is0.8g·L-1.(2) The activated sludge not become resistant to TCP during the31-day continuous operation with solid form TCP was added to reactor in two stages. The volume reduction of sludge reached41%with single2,4,5-Trichlorophenol(TCP) Comparing with the control experiment, the biodegradability and settling properties of the activated sludge were decreased. Under the actions of TCP combined with nano-sized magnetic particles, the volume reduction of sludge reached34%, the removal efficiencies of COD, nitrogen, and phosphorus as well as the sludge settling property were not significantly influenced.(3) The properties of the sludge flocculation, for example, color and structure, from tan, compact gradually becoming mucous yellow, loose and difficult to settlement with single TCP Comparing with the control experiment. On the contrary, the activated sludge of R2, R3, which is added nano-sized magnetic particles, in black granular form, a compact structure of sludge floc was formed. What is showed above, further proof that nano-sized magnetic particles help to improve sludge sedimentation performance with the TCP alone.(4) After31d’s operation, the dehydrogenase activity was improved by10%~18%and exhibited an accumulative effect over time. It was observed with an optical microscope that the structure of sludge from R4is loose, and the species and amounts of protozoon and metazoan were disappeared expect small amount of aspidisca and filamentous bacteria. Conversely, the species and amounts of protozoon and metazoan were increased and a compact structure of sludge floc was formed in the sludge from R2, R3.(5) During3Id’s operation, TCP was not detected in effluent of the four reactors. Its main migration and concentration to sludge, part may be changed into others substances by microbiology or metazoan degradation, But it is still not sure that TCP is how to transformation and what form exist in the system, which is required to further research.All of the experiment conclusions showed that, using nano-sized magnetic particles and uncoupler to limit the sludge yield in the activated sludge system was feasible.