Frequently Asked Questions

An evaporator concentrates a liquid by removing water while keeping it pumpable; a dryer (like an ATFD) takes that concentrate further, to a dry solid. Most ZLD trains use both in sequence — the evaporator reduces volume dramatically, and the ATFD finishes to a handleable solid.

Dairy & food processing, pharmaceutical & API, chemical & petrochemical, effluent treatment/ZLD, sugar & distillery, and textile & dyeing. Each sector has distinct feed chemistry and regulatory requirements — see our Industries page for sector-specific detail.

KWS manages the full lifecycle in-house: process study, equipment design, fabrication, civil coordination, installation, commissioning, operator training, and ongoing AMC support. You deal with one team from enquiry to handover.

Yes. Our Revamping & Modification service covers capacity enhancement, MVR/TVR retrofits, control and automation upgrades, and material changes on existing plants regardless of original manufacturer.

ISO 9001:2015 quality management, IBR (Indian Boiler Regulations) approved fabrication, ASME code pressure vessels, and all ZLD plants are engineered to CPCB norms. Material Test Reports, WPS/PQR, and NDT documentation are supplied as standard.

Falling film suits low-to-moderate viscosity, heat-sensitive feeds (dairy, pharma, juices). Forced circulation handles viscous, scaling or crystallising streams. MVR delivers the lowest operating cost where electricity is cheap relative to steam. Multiple Effect Evaporators (MEE) balance capital and steam economy for most effluent and process duties. KWS conducts a process study and recommends the best fit.

A 2-effect MEE roughly halves steam use versus a single-effect unit; a 5-effect system cuts it to about one-fifth. With MVR enhancement, steam consumption can fall by 90–95%. The optimum number of effects is determined by your steam cost, cooling availability, and target payback period.

TVR (Thermo Vapour Recompression) uses a steam ejector — no moving parts — to recompress secondary vapour using high-pressure motive steam. Low capital, zero electrical load. MVR (Mechanical Vapour Recompression) uses an electric compressor, achieving 30–60× steam economy but at higher capital cost and with an electrical load. TVR suits plants with cheap high-pressure steam; MVR suits sites where power is cheaper than steam.

SS 304 and SS 316L for most food, dairy, and chemical duties; Duplex SS for moderately corrosive streams; Hastelloy C276 and Nickel for highly aggressive caustic or acid services. Pharma units are finished to Ra ≤ 0.4 µm with full traceability.

Once reject TDS climbs past roughly 35,000 mg/L, membrane systems become uneconomical due to osmotic pressure and fouling. Evaporation-based ZLD takes over from there — it can concentrate feeds to 300,000–400,000 mg/L with no upper TDS limit.

CPCB mandates ZLD for several sectors including textile dyeing units and certain chemical and pharma categories, typically based on effluent volume and location. CETP-linked units often have specific norms. Share your sector and location and we'll confirm applicability.

Typically: pre-treatment (screening, pH adjustment), a Multiple Effect or MVR evaporator for bulk concentration, a crystalliser for salt formation, a centrifuge for salt–liquor separation, and an Agitated Thin Film Dryer (ATFD) for final solids drying. KWS supplies and commissions the complete train.

Yes. Evaporated condensate typically contains only 200–300 ppm TDS and is suitable for direct reuse in most industrial processes — dyeing, cooling, boiler feed after polishing. It also arrives at elevated temperature (50–70 °C), saving reheat energy.

Recovered salt is either sold for reuse where purity allows (e.g., sodium sulphate from textile effluent) or safely disposed of to an authorised landfill per CPCB guidelines, depending on effluent source and salt composition.

Operating cost depends heavily on configuration (MEE vs MVR) and local steam and power tariffs. An MEE-based system is steam-intensive; an MVR-based system trades steam for electricity. KWS's free process audit quantifies both options for your specific utility costs.

Typically 8–28 weeks depending on system type and capacity. Falling film units are fastest (8–14 weeks). Full ZLD systems take longest (16–28 weeks) due to the additional process stages — crystalliser, centrifuge, and ATFD — and their integration.

Feed composition/TDS, required throughput (L/hr or KLD), target concentration or output form (pumpable concentrate vs. dry solid), available utilities (steam pressure, power tariff), and site location. The more detail provided, the more precise the first proposal.

Yes. KWS manages installation, commissioning and operator training in-house. Civil and structural work is co-ordinated as part of the project scope where required — you don't need to manage multiple contractors.

Yes, especially for ZLD and complex multi-stage projects. Being based in Chennai, Tamil Nadu, we can reach most sites in South India quickly. For plants in other regions, a preliminary process study based on feed data usually precedes a site visit.

Yes. Annual Maintenance Contracts (AMC) include defined SLAs, a guaranteed 48-hour on-site response for critical breakdowns, preventive maintenance schedules, and spares stocked for all major KWS models.

Our Audits & Revamping service covers any evaporation or ZLD plant regardless of original manufacturer — process audits, energy optimisation studies, capacity enhancement, and MVR retrofit assessments.

Critical and fast-moving spares are stocked at our Chennai facility for all major KWS models and dispatched same or next day. Wear parts and consumables are available on short lead times. Criticality planning as part of AMC ensures you hold the right buffer stock on site.