How to han­dle wastew­a­ter with low en­vi­ron­men­tal and en­ergy im­pacts

DEMM Engineering & Manufacturing - - CASE STUDY -

One of Aus­tralia's most re­mote and en­vi­ron­men­tally aware lo­cal au­thor­i­ties will open an Aus­tralian- en­gi­neered wastew­a­ter treat­ment plant this month that cuts main­te­nance, en­ergy de­mands and OH&S is­sues.

The cost- ef­fi­cient wastew­a­ter treat­ment sys­tem is cur­rently be­ing as­sem­bled (first half of 2018) by Aus­tralian com­pany CST Wastew­a­ter So­lu­tions for in­stal­la­tion on World- Her­itage listed Lord Howe Is­land in the sec­ond half of the year, to re­place the ex­ist­ing waste man­age­ment fa­cil­ity on the Is­land, 900 km off the coast of Eastern Aus­tralia.

The two-stage sys­tem–suit­able for smaller, re­mote and eco­log­i­cally sen­si­tive com­mu­nity, mu­nic­i­pal, agribusi­ness and in­dus­trial ap­pli­ca­tions – was se­lected by the Is­land Board of Lord Howe af­ter ex­ten­sive test­ing to de­ter­mine the best so­lu­tion for the man­age­ment and dis­posal of waste gen­er­ated on the is­land.

“It uses a com­bi­na­tion of coarse and fine screen­ing and ad­vanced dry com­paction KDS sep­a­ra­tor tech­nol­ogy to pro­duce a more hy­gienic and more com­pact out­put that is eas­ier to han­dle and trans­port. The sys­tem is more eco­nom­i­cal, com­pact and uses less en­ergy and min­i­mal wa­ter com­pared to al­ter­na­tive sys­tems,” says CST Wastew­a­ter So­lu­tions’ Manag­ing Di­rec­tor, Michael Bam­bridge.

Ja­panese-man­u­fac­tured and Aus­tralian-en­gi­neered KDS sys­tems–for which CST Wastew­a­ter So­lu­tions is ex­clu­sive dis­trib­u­tor

– are be­ing in­tro­duced to the Asia- Pa­cific for com­pact de­wa­ter­ing ap­pli­ca­tions rang­ing from food pro­cess­ing, food waste, grease trap and waste oil through to mu­nic­i­pal wastew­a­ter sludge, live­stock ma­nure and agribusi­ness pro­cesses.


CST also dis­trib­utes the Smith & Love­less PISTA 360 fine screen­ing tech­nol­ogy, which re­moves 95 per­cent of grit as small as 105 mi­crons (140 mesh).

The tech­nol­ogy sets an en­tirely new bench­mark for grit re­moval, which has t yp­i­cally been set at 95 per­cent as small as 250 mi­crons, says Bam­bridge.

The tech­nol­ogy also:

• Re­duces the enor­mous cost of de- sand­ing down­stream aer­a­tion basins, chan­nels and di­gestors.

• Re­duces dam­age to down­stream equip­ment from wear.

• Elim­i­nates the loss of ef­fi­ciency of down­stream pro­cesses through loss of ac­tive vol­ume.

• En­hances Waste Wa­ter Treat­ment

Plant re­li­a­bil­ity.

• Re­duces OH&S haz­ards in­volved in un­clog­ging sys­tems.

• Helps to pre­vent en­vi­ron­men­tal spills from blocked and f looded sys­tems.


The ex­ist­ing waste man­age­ment fa­cil­ity for Lord Howe Is­land sorts var­i­ous waste streams in­clud­ing food waste, pa­per and card­board, green waste, re­cy­clable ma­te­ri­als re- us­able ma­te­ri­als and gen­eral waste. Sep­tic Waste from the res­i­den­tial and com­mer­cial sys­tem is also treated at this fa­cil­ity, drawn from about 220 wastew­a­ter sys­tems on the is­land, 25 of which are com­mer­cial op­er­a­tions. Cur­rently pumpouts are delivered to the fa­cil­ity via a 1,800 litre wastew­a­ter tanker.

CST Wastew­a­ter So­lu­tions was tasked by the Lord Howe Is­land Board to re­view a “best fit” sludge de­wa­ter­ing sys­tem for the sep­tic waste, be­cause the cur­rent in­fra­struc­ture is be­com­ing out­dated and the ex­ist­ing dry­ing beds are to be de­com­mis­sioned. Work­ing with Lord Howe Is­land Board’s Project Man­ager, CST Wastew­a­ter So­lu­tions de­vel­oped an op­ti­mal so­lu­tion that com­bined out­stand­ing en­vi­ron­men­tal per­for­mance with equally strong OHS per­for­mance – and which has a much smaller foot­print than the dry­ing rack sys­tem used cur­rently, says CST.

CST’s new t wo stage sys­tem com­prises:

1. The first stage is a CST Screen Ex­trac­tor with coarse screen­ing at 6.0mm up front to re­move plas­tic, rags and other dis­pos­als t yp­i­cally found in com­mu­nity, com­mer­cial and in­dus­trial waste wa­ter treat­ment plants.

2. The sec­ond stage em­ployed CST’s new KDS Sep­a­ra­tor tech­nol­ogy for fine screen­ing and de­wa­ter­ing of the fines. The KDS sys­tem was de­vel­oped in Ja­pan, a coun­try which is highly fo­cused on food and wa­ter pu­rity. CST Wastew­a­ter So­lu­tions en­gi­neers KDS’ lat­est tech­nolo­gies into Aus­tralian- en­gi­neered pack­ages spec­i­fied to achieve best re­sults in in­di­vid­ual lo­ca­tions, such as Lord Howe Is­land.

The com­pact KDS multi- disc roller sep­a­ra­tor fea­tures a unique self- clean­ing de­wa­ter­ing and con­vey­ing sys­tem with oval plate sep­a­ra­tion and trans­fer struc­ture that pre­vents clog­ging and per­mits au­to­matic con­tin­u­ous oper­a­tion that han­dles oily and fi­brous ma­te­rial with ease.

“This sim­ple-to- main­tain sep­a­ra­tor of­fers a high through­put within a small body, with the small­est model be­ing just un­der 350mm wide and weigh­ing 50 kg. It is ideal for ap­pli­ca­tions such as Lord Howe Is­land and other smaller com­mu­ni­ties and in­dus­trial ap­pli­ca­tions through­out the Asi­aPa­cific, in­clud­ing coastal, re­mote and eco­log­i­cally sen­si­tive ar­eas. It is more hy­gienic and pro­duces an out­put that is twice as light and half the cost to trans­port for dis­posal, com­pared to other sys­tems. It is also ex­tremely com­pact, en­ergy ef­fi­cient and uses min­i­mal wa­ter,” says Bain­bridge.

De­signed for ef­fi­ciency, sus­tain­abil­ity and con­ser­va­tion of re­sources in small-to- medium ap­pli­ca­tions, the en­ergy- ef­fi­cient KDS sep­a­ra­tor con­sumes as lit tle as 0.06kW hr of elec­tric­ity and uses no wash wa­ter. Com­pared to al­ter­nate tech­nolo­gies it saves on power, space and money, he says.

“The KDS sep­a­ra­tor uses a frac­tion of the power of a cen­trifuge and in­volves no wa­ter us­age dur­ing oper­a­tion, un­like a belt press or a screw press. For a rel­a­tively low in­vest­ment cost, it of­fers a high- per­for­mance al­ter­na­tive for ex­am­ple to sludge dry­ing beds and geobags.”

The KDS tech­nol­ogy can also be used for thick­en­ing of dis­solved air f lota­tion sludge – a very com­mon ap­pli­ca­tion through­out waste wa­ter op­er­a­tions – in which role it achieves solids cap­ture of 97 per­cent thick­ened sludge at a dry­ness of 17 per­cent. Waste ac­ti­vated sludge dry­ness lev­els are t yp­i­cally 15-25 per­cent.

The com­pact ro­ta­tional oval plate struc­ture achieves high trans­porta­tion and sep­a­ra­tion ef­fi­cien­cies, while the sim­plic­ity of the ma­chine’s over­all struc­ture of­fers low main­te­nance, achiev­ing cost and OH&S ben­e­fits through less han­dling be­ing re­quired to clear haz­ardous ma­te­ri­als.

The ‘unique’ self- clean­ing ac­tion of the KDS sep­a­ra­tor, which is avail­able in hy­draulic ca­pac­i­ties from 264- 4092 gal/ hr (ap­prox. 1000-15490 litres) with in­put solids con­tent of t wo per­cent

Ap­pli­ca­tions for which the sep­a­ra­tor is de­signed:

• Food pro­cess­ing waste, in­clud­ing snack­foods, kitchen and restau­rant waste, raw wastew­a­ter ( pri­mary screen­ing) and sludge.

• Sewage treat­ment, in­clud­ing raw wastew­a­ter ( pri­mary screen­ing) and sludge to land­fill.

• Abat­toir, feed­lots, and dairy farm wastew­a­ter and sludge. Cat­tle ma­nure cake dry­ness of 25- 35 per­cent is t yp­i­cally achieved.

• Pig farm raw ma­nure and sludge, with cake dry­ness of 20- 30 per­cent.

• Bar­rel pol­ish­ing wa­ter, wa­ter- based paint wastew­a­ter, grease trap waste, dye­ing wastew­a­ter, waste oil, and plas­tic re­cy­cling.

• Seafood pro­cess­ing.


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