Research On Domestic Wastewater Treatment By Biofilm Reactor Based On Waste Cotton Cloth

The biofilm reactor?BR?has already gained large utilization with simple structure and wonderful effect of wastewater biological treatment.The choice of a suitable biofilm carrier is vital to the decomposition and removal of organic contaminants from domestic wastewater.Cotton materials have been used widely for various domestic,commercial and industrial activities due to their increasing availability and special characteristics including low price,gas permeability,softness,environmental sustainability,biodegradability and hydrophilicity.In view of the current status of solid waste treatment and disposal technologies,it is imperatively essential to adopt more sustainable and innovative techniques to reduce the impact of solid waste including waste cotton cloth on human health and the integrity of the ecosystem.Thus,the current study examined the performance of non-modified waste cotton cloth?NM-WCC?and modified waste cotton cloth?MWCC?in the removal of organic pollutants from domestic wastewater as an emerging technique for waste textile resource management and reuse.The NM-WCC biofilm carrier was self-made with discarded cotton cloths cut into smaller strips with 66 cm long and average weight of 2.4 g each.The surface of waste cotton cloth was modified through the hydro-sulphuric acid?H₂SO₄?method to enhance the physical characteristics of the material such as hydrophilicity and biofilm attachment.Two self-made biofilm reactors;R1?installed with NM-WCC?and R2?fixed with MWCC?were used for the experiment.To achieve the aim of this study,an experiment was carried out to compare and analyse the biofilm formation on the two carriers and their respective pollutants removal efficiencies from simulated wastewater.The R2 had the better removal efficiency of organic pollutant and higher density of biofilm formation.During the biofilm formation experiment,the average removal efficiency of COD,NH₄⁺-N and TP in R2 were 92.0%,75.7%and 53.7%respectively whiles the removal rate of COD,NH₄⁺-N and TP in R1 were 85.9%,69.4%and 49.0%respectively.So R2 was selected for the subsequent phases of the project.Furthermore,the single factor and orthogonal experiments were conducted to explore the effect of various parameters on pollutant removal efficiency of R2 and to determine the optimum parameter combination of the various factors.Afterwards,the R2 was used to treat real municipal domestic wastewater and its suitability as well as viability was explored.As a final point,the relevant mechanism analysis was discussed.After a rigorous study and analysis of the biofilm reactor installed with waste cotton cloth carrier in domestic wastewater treatment,the following conclusions were drawn:The biofilm formation experiment indicated that the density,thickness of biofilm and the pollutant removal efficiency of R2 was higher than R1.Also,the period of biofilm maturation in R2 was shorter than R1.This implies MWCC biofilm carrier is more effective and suitable for pollutant degradation than NW-WCC biofilm carrier.The single factor test of R2 in treating simulated domestic wastewater showed that the organic load?influent COD?,FR,HRT,DO and temperature as the operating parameters had significant effect on pollutant removal efficiency.Orthogonal experiment with FR,HRT,DO and temperature factor combinations showed that the best treatment efficiency was attained when HRT was 10 h,DO 3.0mg/L,temperature 35°C and FR of 65.0%.The examination of R2 for the real domestic wastewater treatment showed that the novel biofilm carrier was feasible and suitable to be utilized in the real world scale of pollutants removal in sewage.During the stable operation of R2 the average removal efficiencies of COD,NH₄⁺-N and TP in real domestic wastewater were reached at95.3%,81.3%and 57.4%respectively.The COD,NH₄⁺-N and TP concentrations of effluent were maintained below 40 mg/L,5 mg/L and 1.5 mg/L respectively.Analysis of the characteristics of waste cotton cloth biofilm carriers showed that water contact angle,water absorption rate,porosity and surface roughness of MWCC was better than NM-WCC which could be attributed to the surface modification of the MWCC.Also,the biomass on MWCC carrier was relatively more than that of NM-WCC carrier.In this research,the waste cotton cloth?WCC?,which is cheap and widely commonly available in the society,was used to make a biofilm carrier installed in a BR for municipal domestic wastewater treatment.The study also presented relevant data demonstrating that modification of waste cotton cloth?WCC?through H₂SO₄utilization increases the removal efficiency of some organic pollutants from domestic wastewater treated in a BR.This method of wastewater treatment is an innovative technique which strategically resolves solid and liquid waste challenges concurrently.In addition,this method is not only effective,feasible,inexpensive,and environmentally friendly but it also serves as a source of resource utilization and reuse.