Physico-chemical treatment of wastewater from clusters of small scale cotton textile units

PEG/Sodium Tripolyphosphate-Modified Chitosan/Activated Carbon Membrane for Rhodamine B Removal

Textile dyes from wastewater effluent are highly toxic to both living species and aqueous environments. An environmentally friendly method to remove hazardous dyes from wastewater in the textile industry has been a challenge. Chitosan (CS) and activated carbon (AC) are widely used as adsorbents for dye removal. However, the poor porosity and unsatisfactory stability of CS and the unfriendly cost of AC limited their applications to be used alone as a single adsorbent. Here, we report a novel method to prepare a CS/AC membrane using PEG10000 as a porogen and sodium tripolyphosphate (TPP) as a cross-linking agent. The adsorption efficiency and reusability of the PEG/TPP-modified CS/AC membrane to remove RhB were investigated based on dynamic and static adsorption models. The results reveal that the adsorption performance of CS/AC membranes was significantly improved after the PEG/TPP modification based on the abundance macroporous structure. The modified CS/AC membrane with a 30% AC doping ratio exhibited an excellent adsorption efficiency of 91.29 and 73.91% in the dynamic and static adsorption processes, respectively. These results provide new insights into designing membranes to remove dyes from wastewater efficiently.

Detoxifying of high strength textile effluent through chemical and bio-oxidation processes

Small-scale textile industries (SSTIs) in India struggled for the economic and environmental race. A full-scale common treatment plant (CETP) working on the principle of destabilising negative charge colloidal particles and bio-oxidation of dissolved organic failed to comply with Inland Surface Waters (ISW) standards. Thus, presence of intense colour and organics with elevated temperature inhibited the process stability. Bench scale treatability studies were conducted on chemical and biological processes for its full-scale apps to detoxify a high strength textile process effluent. Colour, SS and COD removals from the optimised chemical process were 88%, 70% and 40%, respectively. Heterotrophic bacteria oxidised COD and BOD more than 84% and 90% at a loading rate 0.0108kgm(-3)d(-1) at 3h HRT. The combined chemical and bio-oxidation processes showed a great promise for detoxifying the toxic process effluent, and implemented in full-scale CETP. The post-assessment of the CETP resulted in detoxify the toxic effluent.

Eubacterial diversity of activated biomass from a common effluent treatment plant

A common effluent treatment plant (CETP) is a biological wastewater treatment facility that receives wastewater from different industries. The activated biomass in the CETP survives on a wide range of chemicals with no fixed wastewater characteristics. We carried out a diversity analysis of this activated biomass using culture as well as culture-independent techniques. Using culture-based techniques, strains belonging to 26 different genera from the phyla Proteobacteria, Actinobacteria and Firmicutes were isolated. The gamma-proteobacteria was the best represented class, with 36.5% of the isolates. Bacterial diversity was also analyzed culture-independently by means of sequence determination of cloned 16S rRNA genes. Twenty-one different genera from the phyla Proteobacteria, Firmicutes, Planctomycetes and Bacteroidetes were identified. The total diversity of the activated biomass was composed of members of five known phyla, represented by 37 genera, with the Proteobacteria constituting the most abundant phylum detected. However, a very large fraction of the diversity represented a hitherto unidentified bacterial population. More than half (50.2%) of the 16S rDNA clones represented unidentified non-culturable bacteria, underlining the vast untapped diversity of CETP communities. Our results also indicate that both culture-based and culture-independent techniques should be combined to cover the microbial diversity of complex ecosystems.