Background:
Textile manufacture is among the most water-intensive industries generating wastewater with high amounts of organic and mineral (dissolved solids and metals) contamination along with extreme pH associated with the treatment of the raw material. Furthermore, dyes, which are generally stable organic molecules, are not effectively removed by municipal wastewater treatment. The common removal methods are chemical (oxidative) and adsorption (e.g., with activated charcoal). Depending on the chemical used, including balancing pH, the former method may generate a large quantity of sludge, while the latter needs to be regenerated or replaced.
Textile wastewater, with its characteristic unpleasant odor and color, poses a serious threat to the water quality in several regions around the globe.
The ever-increasing generation of textile effluent on the one hand and stringent legislative regulations of its disposal on the other, including the increasing demand for meeting zero liquid discharge (ZLD), has stimulated the need for developing new technologies to process and reclaim this effluent while keeping the energy, maintenance and manpower footprint of the solution as minimal as possible. The technology answering all these criteria is The Natural Biological System.
AYALA Natural Biological Systems Pvt Ltd has perfected state-of-the-art engineered natural solutions that have a life of their own, require no energy to operate, and have minimal maintenance demands. AYALA’s breakthrough Natural Biological System™ technology separates water treatment from reliance on energy, manpower, and chemicals. It is endorsed as a sustainable water treatment technology by the World Bank and others.
The NBS™ technology converts existing open spaces into an active green landscape that does not require fossil energy or complicated conveyance systems. The main instruments are: existing free spaces, topographical analysis, sturdy infrastructure, local labor and materials, a natural, sustainable outlook with a flexible perspective to the future, capable of expanding and responding to local changes. The NBS™ is suitable for the treatment of the most concentrated industrial effluent.
The treatment is modular and tailored with plants, aggregates, and hydraulic layouts per water quality demands and onsite conditions. The NBS™ treatment naturally digests organic matter and dissolved nutrients and sequesters minerals and metals without producing sludge. Furthermore, no energy is consumed during the process.
Treatment Process, footprint, and project estimates:
The Natural Biological System™ has extremely high-performance indicators, removing pollutants from raw industrial, domestic, and agricultural sewage to the levels of unrestricted irrigation and better. The treatment process is tailored to the site condition and generally consists of the following:
- Gravitational settling in sealed or open and vegetated (“living mattress”) settling Footprint: 2 d HRT
- Organic matter, nutrient, and suspended solid removal in a sequence of hybrid flow NBS-Treatment Basins tailored to topography and designed for use with local commodities and labor, total treatment area: 2-7 m2/m2 per day depending on water quality
- Collection outlet with treated water ready for designated use, e.g., aquifer replenishment, inland irrigation use, rehabilitation of surface water, or highly effective RO polishing for reclamation in processes that require very low dissolved solids
- Operation and maintenance typically require 1-2 offices from the gardening and maintenance trade per MLD capacity.
The fate of Pollutants in the NBS™
Three primary processes are at work in the NBS™: sequestration (nucleation), volatilization, and mineralization. The fate of pollutants depends on the susceptibility to one or another process, and the system is tailored to enhance the desired effect. Organic matter (COD) is subject to all three; hence some are fixed into plants and microbes, some are released as small molecules into the atmosphere, either as CO2 or CH4, and the rest is fixed under reducing conditions into peat/mulch. Metals and salts are generally retained as adsorbed oxides or complexes near the roots. These will accumulate almost indefinitely and will not be released to the effluent for hundreds of years. Ions that are used in biological systems, e.g., nutrients (nitrogen, sulfur, phosphorus), are partially adsorbed and partially converted to biomass.
Case Studies of Textile Effluent
1.Nikunj Fabrics, Vapi (India)
A Natural Biological System to treat textile effluent was established in 2017 at Nikunj Fabrics Pvt Ltd, at Vapi, near Mumbai, India. The system is comprised of tanks in series ranging in size from 140- 300 m2 for a provisional total of 750 m2 with an eventual area of 900 m2. The daily flow rate is 150-180 m3 d-1, with a target flow rate at the maturation of 250 m3 d-1. Inlet COD values are 1000-10000 mg L-1, while the outlet is 20-608 mg L-1. The outlet water is dye-free to the unaided eye. In addition, the NBS™ removes Total Dissolved Solids (TDS) at a rate of 30-50% derived from conservative elements such as NaCl and 40-80% for nutrients such as sulfate and nitrate.
2.MAS-Fabrics, Sri Lanka – pure intentions for green nature-based solutions
MAS Fabrics is the number one supplier of intimate and activewear in Sri Lanka and South Asia. The largest division of MAS Holdings, the consistent pursuit of innovation in product, service offering, and process over three decades has made MAS Intimates a preferred partner of global brands such as Victoria’s Secret, Calvin Klein, Gap, Athleta, Hanes Brands International, H&M and Tchibo. Considered an excellent place to work, MAS Intimates also is committed to reducing the water footprint of the inherently water-demanding textile industry. To sustainably plan for long-term hydrological needs, MAS Fabrics entered into an innovative and multi-faceted sustainability plan with AYALA NBS for a variety of projects that range from sludge dewatering, total dissolved solids removal of RO reject water to the replenishment of bore-wells and aquifers by comprehensive management and harvesting of onsite water resources.
Following is a list of AYALA NBS & MAS Fabric sustainability projects:
| Project / Site | Target |
| 1. MFP – Giriulla NBS | Treating Raw Sewerage and discharge to the open wetland. Phase I Capacity: 100 Cu.m/day |
| 2. MAS Active Kreeda Vaanavil NBS for | Treating RO Reject Water and % of STP treated Discharge, back to RO Inlet. Capacity: 60 Cu.m/day |
3. MFP – Thulhiriya NBS for Existing Wetland Inlet | Reduce Suspended Solids and Surfactant based foaming plus final polishing. |
4. MAS Intimates – Linea Clothing Hostel NBS | Treating Raw Sewerage / on–site management to zero liquid discharge. Capacity: 200 Cu.m/day |
5. MAS Intimates Vidiyal Wetland NBS | Treating RO Reject Water and % of STP treated Discharge, back to RO Inlet. Capacity: 100 Cu.m/day |
6. MFP – Thulhiriya Sludge Management NBS | Secondary Clarifier Biological Sludge Slurry with 3-5% Solid content. Capacity: 50 Cu.m/day Slurry. |
Treatment of RO Reject Water at MAS Active Kreeda Vaanavil by NBS™
Conclusion:
As the water-energy nexus worsens worldwide, water-intensive industries conclude that a reliable, stable, and nature-based solution is necessary to maintain sustainability. This is the direct purpose of the Natural Biological System™ technology: to restore balance with the thermodynamic engineering of natural elements.