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Relative efficacy of five common weeds—of the kind that are either rooted in soil or which freely float over water—was assessed in rapid, effective and sustainable treatment of sewage at pilot plant scale in the recently developed and patented SHEFROL® bioreactors. The plants were utilized in a unit of capacity 12,000 liters/day (LPD) which, after two years of use, was enlarged to handle 40,000 LPD of sewage. It was then further expanded after an year to treat 57,000 LPD. All the five weeds, of which none has previously been tested in a pilot-scale SHEFROL, were able to foster highly efficient primary treatment (in terms of suspended and total solids) and secondary treatment (in terms of BOD and COD) to levels exceeding 85% in most cases. Additionally, the weeds also helped in achieving significant tertiary treatment. At different hydraulic retention times, and at steady state, the five weeds achieved treatment of BOD, COD, suspended solids, nitrogen, phosphorous, copper, nickel, zinc, and manganese in the ranges, 80–95, 79–91, 82–95, 61–71, 51–73, 37–43, 30–38, 39–47, and 27–35%, respectively. It all occurred in a single process step and without the use of any machine or chemical. This made the system not only simple and inexpensive to install but also to maintain. Over continuous long-term operation for four years, the system was seen to be very robust as it was able to handle wide variations in the volumes and characteristics of sewage, as well as absorb shock loads without compromising the reactor performance. The sustainability of the system can be further enhanced by upgrading it to a circular biorefinery. Energy sources in the form of volatile fatty acids (VFAs) can be extracted from the weeds removed from SHEFROL and then the weeds can be converted into organic fertilizer using high-rate vermireactors recently developed by the authors. A novel and inexpensive, yet very efficient sewage treatment system is presented. The versatility and robustness of the system has been assessed at pilot plant scale for several years. The long-term continuous studies establish the efficacy of five common weeds—not hitherto explored at pilot plant level—which can serve as the main bioagent(s) in the sewage treatment system. The system has the potential of being transformed in to a closed-loop-no-waste biorefinery [ABSTRACT FROM AUTHOR]

The wastewater ensuing from public eateries is higher in its chemical and biological oxygen demand (COD and BOD) as also its oil, grease, and protein content than sewage. For this reason such wastewater is much harder to treat; its content of fats, proteinaceous material, and xenobiotics mounting major challenges. But in most of the developing world about 80% of such wastewater is discharged untreated and the remaining is mixed with sewage going to the treatment plants. This happens due to the prohibitively high cost of treatment that is entailed if these wastewaters are to be treated by conventional activated sludge processes (ASPs) or a combination of anaerobic digestion and ASPs. The practice of allowing eatery wastewater to join sewage en route sewage treatment plants increases the load on the latter, especially due to the high fat and protein content of the former. The present work describes attempts to use the recently developed and patented SHEFROL® technology in affecting treatment of wastewater coming from a typical eatery. After establishing feasibility at bench scale, the process was tested in a case study at pilot plant scale for treating 12,000 litres/day (LPD) of wastewater being generated by the eateries situated in the campus of Pondicherry University, India. The capacity of the pilot plant was then expanded to 30,000 LPD. Despite operating the units at a very low hydraulic retention time (HRT) of 2 ± 0.5 h, due to the limitations of land availability, which translates to a rate about three times faster than a typical ASP, over 50% removal of COD and BOD, and similarly substantial removal of other pollutants was consistently achieved. Given that the SHEFROL units can be set up at a negligible cost, the findings indicate that SHEFROL technology can be used to significantly yet inexpensively pre-treat eatery wastewaters before either sending them for further treatment to conventional sewage treatment plants, higher-end SHEFROL units, or discharging them directly if neither of the other two options is available. [ABSTRACT FROM AUTHOR]