Sugar industry produces a variety of organic byproducts causing disposal as well as environmental issues. This study investigated the safe use of these byproducts in assessment of soil physicochemical properties and metal accumulation in rice. A field experiment was performed with following treatments: control only NPK (CF), NPK + sugarcane bagasse (SB), NPK + press mud (PM), NPK + sugarcane vinasse (SV), NPK + SB + PM (SB + PM), NPK + SB + SV (SB + SV), NPK + PM + SV (PM + SV), NPK + SB + PM + SV (SB + PM + SV). Total byproduct input was (1.25 t ha⁻¹) as recommended for organic inputs in the local area. The results indicated that integrated use of these amendments with chemical fertilization improved soil properties and rice yield. Organic matter was significantly improved in SB + SV (191.3%), SB + PM + SV (164.4%), and SB + PM (150.9%). Total N was significantly enhanced in SB + SV (193%), SB + PM + SV (166%), and SB + PM (152.5%); extractable P was high in SB (103%), PM + SV (89.7%), and SB + PM (51%); extractable K was significantly improved in PM (39.6%) and SB (33.4%); extractable Zn was significantly enhanced in SB (1172.8%), SV (829.2%) and PM (819.1%) in soil. Rice grain yield was significantly enhanced in SB (213.1%) and PM (208.8%) while combined application also improved the yield with reference to the CF. The application of SB + PM improved N (58.7%), P (27.4%), K (11.5%), and Zn (166.4%) concentration in grain, while metal accumulation was within the permissible limit. Zn concentration was significantly enhanced in SB + PM (166.4%) whereas the concentration of Cd and Pb was significantly reduced with the application of byproducts. Health assessment results showed no harmful effects for humans. Results conclude that these byproducts are good nutrients source and improve soil physicochemical properties without any health hazards.

Bagasse activated carbon (AC) and the new type of activated carbon (KAC) prepared with reactivation method of ZnCl₂-KOH were modified with triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The as-modified adsorbents for CO₂ separation were investigated by thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), elemental analysis, N₂ adsorption–desorption, as well as scanning electron microscopy (SEM). When the content of amine group is 5%, the CO₂ adsorption quantity of TEPA-loaded adsorbents reaches the highest at 60 °C (3.62 mmol/g for KAC and 1.98 mmol/g for AC, respectively). With a more abundant pore structure, KAC is more suitable for amine modification and its adsorption capacity of CO₂ is higher than that of AC after amine modification. Cyclic adsorption–desorption tests showed satisfactory regenerations for the modified adsorbents. Compared with other adsorbents, such as activated carbon, microporous zeolite, and mesoporous molecular sieve reported in literature, the new adsorbent prepared from the by-product of sugar industry has good performance (1.05–3.14 mmol/g larger than those of others) under the same conditions (60 °C and 15% partial pressure). The results are expected to provide scientific basis for the practical application.

The global sugarcane production is about 1.91 billion tons annually and is concentrated in tropical regions, particularly in developing nations in Latin America and Asia. According to the UN Food and Agricultural Organization (FAO), there are over 100 countries producing sugarcane today. The increase in sugarcane production implies a proportional increase in sugar industry wastes. As a consequence of such increasing trend, sugar industries are facing severe environmental problems due to the lack of sustainable solutions for their waste management. Therefore, immediate attention is required to find a proper way of management to deal with sugar industry wastes and effluent in order to minimize environmental pollution and associated health risks. In this paper, different sources of solid and liquid wastes from sugarcane agriculture and associated sugar agro-industries are reviewed and valorization approaches of these different wastes are discussed. Some of the important resource recovery options from sugar industry wastes, which have been discussed in this review, include ethanol production, recovery of chemicals, use of bagasse and bagasse fly ash as adsorbents in water treatment and building materials. Technologies associated with the treatment of wastewater from sugar industries and efficient ways of utilization of this treated water in agriculture with special attention to measurement of crop water use efficiency are reviewed in view of our own research activities carried out in the past.

Agroindustrial by-products and residues from treatment of sewage sludge have been recently recycled as soil amendments. This study was aimed at assessing toxic potential of biosolid, obtained from a sewage treatment plant (STP), vinasse, a by-product of the sugar cane industry, and a combination of both residues using Allium cepa assay. Bioprocessing of these samples by a terrestrial invertebrate (diplopod Rhinocricus padbergi) was also examined. Bioassay assembly followed standards of the Brazilian legislation for disposal of these residues. After adding residues, 20 diplopods were placed in each terrarium, where they remained for 30 days. Chemical analysis and the A. cepa assay were conducted before and after bioprocessing by diplopods. At the end of the bioassay, there was a decrease in arsenic and mercury. For the remaining metals, accumulation and/or bioavailability varied in all samples but suggested bioprocessing by animals. The A. cepa test revealed genotoxic effects characterized by different chromosome aberrations. Micronuclei and chromosome breaks on meristematic cells and F₁ cells with micronuclei were examined to assess mutagenicity of samples. After 30 days, the genotoxic effects were significantly reduced in the soil + biosolid and soil + biosolid + vinasse groups as well as the mutagenic effects in the soil + biosolid + vinasse group. Similar to vermicomposting, bioprocessing of residues by diplopods can be a feasible alternative and used prior to application in crops to improve degraded soils and/or city dumps. Based on our findings, further studies are needed to adequately dispose of these residues in the environment.

Worldwide, the requirement of electrical energy has increased with an increase in population. Thus, there is a need to develop an alternative source of sustainable energy, such as microbial fuel cell (MFC). MFC is a better option of energy generation and can provide a renewable resource which utilizes wastewater into power by the help of microorganisms. MFC is one of the advanced methods for treating wastewater and simultaneously producing current and voltage. Dual-chambered MFC was prepared using two plastic boxes (500 ml) by using wastewater as an anolyte. Different types of mediators are used in MFC including methylene blue, potassium ferricyanide, and EDTA to facilitate and higher the efficiency of electron transfer from the MFC to the electrode. Maximum OCV and current output of sample 1 (Budha Talab pond water) were 0.86 V and 75.1 mA and of sample 2 (Jaypee cement plant) were 1.42 V and 122 mA. The maximum current output of sample 3 (sugar industry, sewage waste, NIT canteen) was 1.3 V. Various physiochemical parameters such as dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were analyzed which affect the power output. The obtained result concluded that wastewater should be feed at a certain time interval to avoid the loss of substrate for organisms in the anodic chamber which lead to the death of the microorganism. Among all, sugar industry wastewater has a high potential for power generation as their physiochemical results are suitable for better power output.

Adsorption is one of the best methods for arsenic removal from water which is established in the last few decades. Biosorption by natural biosorbents and agricultural by-product is an environmental friendly approach and has proved to be a cost-effective and non-hazardous technology for the removal of heavy metals from water. This paper describes batch test findings conducted to evaluate the feasibility of using sugarcane bagasse (SCB) as an industrial by-product of sugar industry to remove arsenic (As) from water and compare the results with the efficiency of activated carbon (AC) for arsenic (As) removal. The effects of three parameters, such as pH, adsorbent dosage (Cₐ), and initial metal concentration (C₀) on the adsorption of arsenic were evaluated by using response surface methodology (RSM). It is discovered that AC and SCB removed up to ~89 and ~98 % of arsenic, respectively. The uptake capacities yielded from the batch experiment were about 31.25 mg/g for AC at pH ~7.4 and 11.9 mg/g for SCB at pH ~9. The equilibrium times achieved were 120 and 150 min for SCB and AC, respectively. This study shows that SCB is an efficient low-cost biosorption for arsenic removal from water.

A laboratory trial was performed to test the sequestration capacity of two minerals (bentonite and zeolite) at three initial concentrations (2.5, 5 and 10%) in order to counter water-soluble nickel (Ni) exceeding the Italian legal limit (10 μg L⁻¹) in carbonation lime disposed of in a field and sampled for an 85-day lab study. The results show a noticeable reduction in water-soluble and bioavailable Ni in lime after the addition of sequestrants, especially at the dose of 5% bentonite or zeolite, thereby indicating a “ceiling effect” of the sequestrant, i.e., an increasing dose could reduce the adsorption capacity and be less effective. The alkaline pH and the presence of organic matter could be the main factors affecting the good performance of sequestrant addition, causing an increase in the negative charge of the organic and mineral colloids and the formation of unavailable Ni precipitates. The 85-day experiment seems to be sufficient to reach an adsorption equilibrium for water-soluble nickel, while for the bioavailable form a longer period appears to be necessary.

The safe disposal of industrial effluents always remained a challenging process because of their high level of nutrients, toxic elements, and salts. A pot experiment was conducted to investigate the effects of various concentrations (5%, 10%, 15%, and 20%) of sugar industry effluent spentwash (SW) fertigated with tab water (TW), on soil properties, crop growth, physiological parameters, yield components, and accumulation of potentially toxic elements (PTEs) in rice (Oryza sativa L.) grains and straw. The results showed that soil physico-chemical properties were modified with rise in SW concentration. Application of 5% SW significantly enhanced the plant growth, and yield components. Photosynthesis rate, transpiration rate, and stomatal conductance were significantly higher under 5% SW concentration in comparison with control. However, SW concentrations of > 5% showed inhibitory effects for all growth, physiological, and yield components. Accumulation of PTEs showed increasing trend with rise in SW concentration. However, under 5% SW concentration, all the PTEs in rice grain and straw were within the permissible limits (PLs) recommended by FAO/WHO and no health hazards were detected by health risk assessment. Based on the study results, 5% SW fertigation with TW can be applied as fertilizer for enhancing the growth and productivity of rice. Graphical abstract

An alcoholic fermentation process is described, involving molasses, the main by-product of the sugar industry, blended with crude olive oil mill wastewaters (OOMWs) and immobilized Saccharomyces cerevisiae cells on delignified cellulosic material (DCM). For comparison, fermentations with free cells were also carried out. Initially, the optimum blending mixture for molasses dilution was sought after, while at a second step repeated batch fermentations at a temperature range 5–30 °C were performed to monitor the operational stability of the system. A 1/1 ratio of OOMWs/tap water blending mixture and cell immobilization resulted in higher fermentation parameters. Ethanol concentration and daily productivity values recorded at temperatures ≥ 20 °C (up to 67.8 g L⁻¹ and 67.6 g L⁻¹ d⁻¹, respectively) could be adopted by the industrial sector, although the decline in fermentation efficiency observed, probably due to the toxicity effects of OOMWs. Finally, the potential of OOMWs treatment for ethanol production is highlighted and assessed.

In the present study, sugar beet mud (SBM) and pulp (SBP) produced as a waste by-products of the sugar industry were mixed with cattle dung (CD) at different ratios on dry weight basis for vermicomposting with Eisenia fetida. Minimum mortality and highest population of worms were observed in 20:80 (SBM₂₀) mixture of SBM and 10:90 (SBP₁₀) ratios. However, increased percentages of wastes significantly affected the growth and fecundity of worms. Nutrients like nitrogen, phosphorus, sodium, increased from initial feed mixture to final products (i.e., vermicompost), while organic carbon (OC), C:N ratio and electrical conductivity (EC) declined in all the products of vermicomposting. Although there was an increase in the contents of all the heavy metals except copper, chromium, and iron in SBM, the contents were less than the international standards for compost which indicates that the vermicompost can be used in the fields without any ill effects on the soil. Allium cepa root chromosomal aberration assay was used to evaluate the genotoxicity of pre- and post-vermicomposted SBM to understand the effect of vermicomposting on the reduction of toxicity. Genotoxicity analysis of post-vermicomposted samples of SBM revealed 18–75 % decline in the aberration frequencies. Scanning electron microscopy (SEM) was recorded to identify the changes in texture in the control and vermicomposted samples. The vermicomposted mixtures in the presence of earthworms confirm more numerous surface irregularities that prove to be good manure.