A pilot-scale assessment of five common weeds in the sustainable treatment of sewage utilizing SHEFROL®, with prospects of a closed-loop biorefinery.

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 weeds­not hitherto explored at pilot plant level­which 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.

Different Species of Epigeic and Anecic Earthworms Cause Similarly Effective and Beneficial Biocomposting-A Case Study Involving the Pernicious Aquatic Weed Salvinia (Salvinia molesta, Mitchell).

As reported recently by the present authors, vermicomposting by the epigeic earthworm Eisenia fetida transforms the highly ligninous and allelopathic aquatic weed salvinia (Salvinia molesta) into a benign organic fertilizer. The present study was carried out with four other earthworm species, including three epigeic species of different sizes and phytophagic habits: Eisenia andrei, Lumbricus rubillus, and Perionyx sansibaricus. One anecic species, with geophytophagous habits, was also explored for comparison: Drawida willsi. The objective was to see whether the type of salvinia transformation caused by E. fetida is a general phenomenon or whether there are significant differences in the nature of biocomposts generated by different earthworm species. Accordingly, the characteristics of the biocomposts separately generated by each of the six species mentioned above were assessed with UV-visible spectrophotometry, Fourier-transform infrared spectrometry, differential scanning calorimetry, thermogravimetry, and scanning electron microscopy. The studies reveal that, with minor variations, the biocomposting by all four species was able to remove the intransigence of salvinia and impart plant/soil-friendly attributes to it in substantial measures. All the findings obtained with different techniques corroborated each other in arriving at this conclusion. Hence, it can be said that, in general, biocomposting by earthworms takes away the toxicity of pernicious weeds such as salvinia, converting them into plant-friendly and soil-friendly biofertilizers.

Role of different earthworm species in nullifying the toxicity of Ipomea carnea and enhancing its utility as a phytoremediator.

The dreaded weed ipomea (Ipomea carnea), has shown promise as a versatile phytoremediator. But I. carnea plants exude several alkaloids and phenols which are harmful to plants as well as animals. Due to this, the weed imparts as much or more toxicity to the soil as it remediates. These authors have earlier found that upon being vermicomposted by Eisenia fetida ipomea loses its toxicity and becomes a benign organic fertilizer with pest repellant attributes. These findings open up the possibility of using earthworms in those segments of land which are sought to be phytoremediated by ipomea so that the earthworms can keep converting the dead ipomea plants and the debris of live plants to fertilizer. The present work has aimed to determine whether the extent and nature of earthworm impact differs from species to species or is similar across different species. It has revealed that the action of each of the four different earthworm species deployed by the authors caused the C:N ratio of ipomea to change drastically ̶ from 28.20 to 15.95 ± 0.75, bringing the vermicomposts to the category of fertilizers fit for horticulture. The Fourier transform infrared (FTIR) spectra revealed that all the species caused a breakdown of the alkaloids and the phenolic compounds present in ipomea, resulting in the weed's detoxification. The earthworms also effected partial degradation of the lignocellulosic content of ipomea to simpler and more soil-friendly constituents like humic acids. Thermogravimetry, differential scanning calorimetry and scanning electron microscopy corroborated these findings. The influence exerted by the four species of earthworms was similarly beneficial in nature and extent.

First-ever study which establishes the general applicability of earthworms in nullifying the toxic impacts caused by ipomea during its use in phytoremediation, thereby greatly enhancing ipomea's value as a phytoremediator. The studies also provide an avenue for the utilization of the otherwise worthless ipomea harvested after phytoremediation or from natural stands.

Vermicompost of the widespread and toxic xerophyte prosopis (Prosopis juliflora) is a benign organic fertilizer.

Prior to the work described in this paper, no report has existed on the use of any xerophyte is generating vermicompost. Now these authors have been able to develop a process with which the highly invasive xerophyte prosopis (Prosopis juliflora) can be vermicomposted. But does prosopis vermicompost (PVC) have any fertilizer value, given that prosopis has strong allelopathy and toxicity? To seek an answer, the authors have assessed the effect of the PVC on the germination and early growth of five common food plants: brinjal (Solanum melongena), chilly (Capsicum annuum), cucumber (Cucumissativus), ladies finger (Abelmoschus esculentus), and tomato (Lycopersicon esculentum). Thereafter the tomato and the brinjal plants were grown to fruition to assess their yield and nutrient value. Whereas no germination of any seed occurred when the soil was fortified with prosopis leaves, there was 20-100% germination of seeds in different plant species when fertilized with equivalent quantities of PVC. The carbohydrate, potassium, and magnesium contents of prosopis fertilized brinjal and tomato fruits were significantly (p ≤ 0.5) higher than the levels of these nutrients present in the market produce. The prosopis vermicompost displayed pest-repellant attributes as well. The findings indicate that the millions of tonnes of prosopis leaves, which have no utility value and of which falling on earth is harmful to the soil, can be used to generate organic fertilizer.

Ability of Indian pennywort Bacopa monnieri (L.) Pennell in the phytoremediation of sewage (greywater).

The freely and abundantly available amphibious plant Indian pennywort Bacopa monnieri (L.) Pennell was able to phytoremediate sewage (greywater) quickly and substantially in SHEFROL® ("sheet flow root level") bioreactors, achieving reductions in the levels of several indicator parameters: suspended solids, chemical oxygen demand, biological oxygen demand, nitrogen, phosphorus, zinc, copper, nickel, and manganese to the extents of about 90%, 76-77%, 80%, 65%, 55%, 56%, 42%, and 41%, respectively at hydraulic retention times of just 6 h. As these indicators of primary, secondary, and tertiary treatments were achieved simultaneously in a single reactor compartment, the system presented in this paper promises to be simple, rapid, and economical, in achieving significant treatment of greywater.